WO2025020655A1 - Optical device, wavelength selective switch and optical device manufacturing method - Google Patents

Abstract

The present application relates to the technical field of optical fiber communications, and in particular to an optical device, a wavelength selective switch and an optical device manufacturing method. The optical device comprises a first part and a second part, wherein the second part is of a periodic structure formed by processing a material to be processed arranged on the surface of the first part, only one interface is arranged between the first part and the second part, the interface is the surface of the first part. The first part and the second part of the optical device provided by the present application are integrated into a whole, so that adverse factors influencing the optical performance of the optical device due to the use of a photolithography process can be avoided, and the reliability risk and the yield loss caused by the use of a photoresist or a bonding process can be reduced.

Description

Optical device, wavelength selective switch and optical device manufacturing method

This application claims the priority of the Chinese patent application filed with the China Patent Office on July 24, 2023, with application number 202310919329.7 and application name “An optical device, a wavelength selective switch and an optical device manufacturing method”, all contents of which are incorporated by reference in this application.

Technical Field

The present application relates to the field of optical fiber communication technology, and in particular to an optical device, a wavelength selective switch, and a method for manufacturing the optical device.

Background Art

Wavelength Selective Switch (WSS) is an optical module that can dispatch laser signals of different wavelengths from one or more input ports to one or more output ports in real time. Grism is a key component in the wavelength selective switch, which includes prism and grating. Grism plays the role of dispersing and folding laser signals of different wavelengths according to wavelength.

At present, the commonly used methods for making prisms are to connect the two independent components of the plane grating and the prism by gluing (method one), or to form grating stripes on the prism by etching (method two). However, the former (method one) has a low yield of optical glue or bonding process, and has large fluctuations (between 30% and 80%), high cost and low production capacity. The latter (method two) requires large-scale modification of the prism surface lithography, which has high development costs.

Summary of the invention

The present application provides an optical device, a wavelength selective switch and an optical device manufacturing method, which can solve the problem in the prior art that the duty cycle, sawtooth angle, surface roughness and other parameters caused by the photolithography process affect the optical performance. The present application is introduced from multiple aspects below, and the implementation methods and beneficial effects of the following multiple aspects can be referenced to each other.

In a first aspect, the present application provides an optical device. The specific optical device includes: a first part (such as a prism or optical encoder described later); a second part (such as a grating or grating ruler described later), wherein the second part is a periodic structure formed by processing a material to be processed disposed on the surface of the first part, and there is only one interface between the first part and the second part, and the interface is the surface of the first part.

The above-mentioned optical device uses the first part as a substrate, and directly processes the material to be processed on the surface of the first part to form a periodic structure as the second part. The first part and the second part can be integrated into one without the need for photolithography, photoresist or bonding processes. Since the optical device is not formed by using photolithography, photoresist or bonding processes, there is only one interface between the first part and the second part of the molded optical device in the embodiment of the present application, and the interface is the surface of the first part. This arrangement can not only reduce the above-mentioned adverse factors affecting the optical performance caused by the photolithography process, but also reduce the reliability risk and yield loss caused by the photoresist or bonding process.

In a possible implementation of the first aspect above, the side of the second part facing away from the interface includes a recess (such as the grating grooves of the grating or grating scale described later), and the distance between the bottom surface of the recess and the interface is less than 100 microns along a direction perpendicular to the interface.

In a possible implementation of the first aspect, the material to be processed is a material to be imprinted, and the second part is a periodic structure formed by imprinting and curing the material to be imprinted disposed on the surface of the first part. That is, in the embodiment of the present application, the first part is used as a substrate, and the material to be imprinted is directly imprinted on one surface of the first part into a periodic structure (as the second part) to achieve the molding of the optical device.

It should be noted that the optical device of the embodiment of the present application is not limited to being formed by an embossing process, and other molding processes can also be used. Any device that can meet the following conditions belongs to the protection scope of the present application: There is only one interface between the first part and the second part of the optical device after molding, and the interface is the surface of the first part. Exemplarily, along the direction perpendicular to the interface, the distance between the bottom surface of the concave portion of the second part and the interface is less than 100 microns.

In a possible implementation of the first aspect, the first part is a prism, the prism includes an input surface and a reflection surface that are not parallel to each other, the input surface is used for inputting optical signals; the second part is a grating, and the grating is formed by processing the material to be processed provided on the reflection surface (i.e., the interface between the prism and the grating ruler). That is, the optical device is a spectroscopic device, which can also be called a prism.

It can be understood that the prism in the spectroscopic device refers to a dielectric block material (glass, crystal material, polymer, etc.) whose input surface is not parallel to the input surface, and the grating in the spectroscopic device refers to an optical element with a periodic structure integrated on the surface.

Exemplarily, the grating is formed by imprinting and curing the material to be imprinted on the reflective surface, without the need for a photolithography process or an optical glue or bonding process, and an integrated prism can be formed, thereby finely controlling the grating shape, improving the line density, and avoiding the problem of low yield when gluing the grating and prism together in the optical glue or bonding process.

The above-mentioned spectroscopic device forms a grating by imprinting the imprinting material on the reflective surface of the prism and curing it, thereby integrating the grating and the prism into one. Together, the solution of integrated gratings can greatly increase the grating density based on existing equipment and processes, without the need to upgrade the UV light source to adapt to high line density and resolution. At the same time, the gratings can avoid the reliability risks and yield losses introduced in the optical glue or bonding process, thereby improving the yield.

In a possible implementation of the first aspect, the grating density of the grating is between 2000 lines/mm and 20000 lines/mm.

It can be understood that the grating density will directly affect the dispersion angle of the grating. The greater the grating density, the greater the dispersion angle of the grating, and the higher the overall dispersion ability of the prism. The grating density of the spectrometer in the embodiment of the present application can be at a relatively high level (up to 20,000 lines/mm). Compared with the prior art, where the line density of the photolithography grating is 2000 lines/mm, there are great challenges. The grating in the prism of the embodiment of the present application has better scalability. It should be noted that the upper limit of the grating density of the embodiment of the present application is not limited to 20,000 lines/mm, but can also be between 2000 lines/mm and 20,000 lines/mm, and can also be below 2000 lines/mm.

In a possible implementation of the first aspect above, the grating includes a plurality of grating lines, and the plurality of grating lines are periodically arranged along an extension direction of the reflecting surface, and along a lateral direction perpendicular to the extension direction, a grating line projection shape of the plurality of grating lines includes any one or more of a trapezoid, a rectangle, a sawtooth, and a triangle.

Since the embodiment of the present application forms a grating by imprinting and curing the material to be imprinted on the reflective surface of the prism, the periodic structure of the grating can be adjusted according to different application scenarios. When a wider wavelength range (i.e., bandwidth) needs to be covered, the grating line projection shape of the multiple grating lines of the prism in the embodiment of the present application can be adjusted to a rectangular or trapezoidal shape. When a higher diffraction efficiency is required at a single wavelength, the grating line projection shape of the multiple grating lines of the prism in the embodiment of the present application can be adjusted to a triangular or sawtooth shape.

In a possible implementation of the first aspect above, a surface of the grating is partially or completely covered with at least one dielectric film.

For example, when the refractive index of the grating area is less than 1.9, a high refractive index dielectric film needs to be covered on the surface of the grating to ensure diffraction efficiency. In addition, adding a layer of low refractive index film on the surface of the high refractive index film can improve the process tolerance and reduce the difficulty of processing.

In a possible implementation of the first aspect, the grating includes a plurality of grating lines, the plurality of grating lines are periodically arranged along an extension direction of the reflective surface, and a top surface and/or a side surface of at least one of the plurality of grating lines is covered with at least one layer of dielectric film.

In a possible implementation of the first aspect above, the grating includes a plurality of grating grooves (i.e., recessed portions on a side of the grating facing away from the reflective surface), the plurality of grating grooves are spaced apart along an extension direction of the reflective surface, and at least one of the plurality of grating grooves is covered with at least one layer of dielectric film.

For example, along a direction perpendicular to the reflection surface, the distance between the bottom surface of the gate groove and the reflection surface is less than 100 micrometers.

In a possible implementation of the first aspect, the material of the dielectric film includes any one or more of TiO 2 , Ta 2 O 5 , and SiO 2 . In some possible implementations, the material of the dielectric film is a dielectric material with a high refractive index of 2.0 or above, such as a polymer material.

In a possible implementation of the first aspect, the first part is an optical encoder; the second part is a grating ruler, and the grating ruler is formed by processing a material to be processed disposed on a surface of the optical encoder (i.e., an interface between the optical encoder and the grating ruler). Exemplarily, the grating ruler is formed by embossing and curing a material to be embossed disposed on a surface of the optical encoder.

In a possible implementation of the first aspect above, the grating scale includes a plurality of grating lines and a plurality of grating grooves (i.e., recessed portions on the back side of the grating scale), the plurality of grating lines are periodically arranged along the extension direction of the surface of the optical encoder, and each of the plurality of grating grooves is arranged at intervals between adjacent grating lines.

Exemplarily, along a direction perpendicular to the surface of the optical encoder, a distance between the bottom surface of the gate groove and the surface of the optical encoder is less than 100 micrometers.

In a possible implementation of the first aspect above, the gate line includes a first surface, and the gate groove includes a second surface; the first surface is a light-blocking area of the optical encoder, and the second surface is a light-transmitting area of the optical encoder, or the first surface is a light-transmitting area of the optical encoder, and the second surface is a light-blocking area of the optical encoder.

In a possible implementation of the first aspect above, the surface of the optical encoder includes any one of the upper and lower surfaces of a cuboid or a ring, a spherical surface, or the inner and outer surfaces of a cylinder.

A second aspect of the present application provides a wavelength selective switch, which includes any optical device in the first aspect and any possible implementation of the first aspect.

The third aspect of the present application provides a method for manufacturing an optical device. The manufacturing method includes: providing a first part; arranging a material to be imprinted on the surface of the first part; imprinting the material to be imprinted using an imprinting template having a set shape, wherein the set shape is periodically arranged along a direction parallel to the extension direction of the surface of the first part; curing and demolding the imprinted material to be imprinted to form a second part on the surface of the first part, wherein there is only one interface between the first part and the second part, and the interface is the surface of the first part.

The optical device directly embosses the material to be embossed on the surface of the first part to form the second part without using a photolithography process or a photoresist or bonding process, so that the second part can be finely controlled to be periodically arranged in a direction parallel to the extension direction of the surface of the first part. The specific shape of the shape is set to increase the line density and avoid the problem of low yield when the first and second parts of the optical device are glued together in the optical glue or bonding process.

In addition, the second part of the embodiment of the present application is integrated with the first part through an integrated integration solution to form an integrated optical device. Based on the existing equipment and process, the line density of the periodically arranged set shape in the second part can be greatly improved, with better scalability, avoiding the reliability risk and yield loss introduced in the optical glue or bonding process, and improving the yield.

In a possible implementation of the third aspect, the second portion includes a concave portion on a side facing away from the interface, and a distance between a bottom surface of the concave portion and the interface is less than 100 micrometers along a direction perpendicular to the interface.

In a possible implementation of the third aspect above, the first part is a prism, and the prism includes an input surface and a reflection surface that are not parallel to each other; the surface of the first part includes a reflection surface, and the material to be imprinted is arranged on the reflection surface; the set shape of the imprint template is periodically arranged along a direction parallel to the extension direction of the reflection surface; the second part is a grating, and the material to be imprinted forms a grating on the reflection surface of the prism after demolding.

The process of forming the grating from the prism in the embodiment of the present application does not use a photolithography process or an optical glue or bonding process. The prism is directly used as the substrate, and the material to be imprinted (such as a polymer material or a glass material) is directly imprinted on the reflective surface of the prism into a grating periodic structure, that is, an imprinting process (such as a nanoimprinting process) is used to directly generate a periodic grating structure on the prism surface, so that the grating shape can be finely controlled, the line density can be improved, and the problem of low yield when the grating and prism are glued together in the optical glue or bonding process can be avoided. In addition, the grating in the embodiment of the present application is integrated with the prism through an integrated integration solution to form an integrated prism. It can greatly improve the grating density based on existing equipment and processes, has better scalability, avoids the reliability risks and yield losses introduced in the optical glue or bonding process, and improves the yield.

In a possible implementation of the third aspect above, the grating density of the grating formed after printing and curing is between 2000 lines/mm and 20000 lines/mm.

It can be understood that the grating density will directly affect the dispersion angle of the grating. The greater the grating density, the greater the dispersion angle of the grating, and the higher the overall dispersion ability of the prism. The grating density of the spectrometer in the embodiment of the present application can be at a relatively high level (20,000 lines/mm). Compared with the prior art, where it is a great challenge to achieve a line density of 2,000 lines/mm for the photolithography grating, the grating in the prism of the embodiment of the present application has better scalability.

In a possible implementation of the third aspect above, the grating formed after printing and curing includes a plurality of grating lines, and the plurality of grating lines are periodically arranged along the extension direction of the reflecting surface, and along the lateral direction perpendicular to the extension direction, the grating line projection shapes of the plurality of grating lines include any one or more of a trapezoid, a rectangle, a sawtooth, and a triangle.

Since the embodiment of the present application forms a grating by imprinting and curing the material to be imprinted on the reflective surface of the prism, the periodic structure of the grating can be adjusted according to different application scenarios. When a wider wavelength range (i.e., bandwidth) needs to be covered, the grating line projection shape of the multiple grating lines of the prism in the embodiment of the present application can be adjusted to a rectangular or trapezoidal shape. When a higher diffraction efficiency is required at a single wavelength, the grating line projection shape of the multiple grating lines of the prism in the embodiment of the present application can be adjusted to a triangular or sawtooth shape.

In a possible implementation of the third aspect, curing includes any one of heat curing, UV curing, moisture curing or thermoplastic curing. It should be noted that the curing form of the embodiment of the present application is not limited thereto, and other curing molding processes may also be used.

In a possible implementation of the third aspect above, at least one dielectric film is partially or completely covered on the surface of the grating.

For example, when the refractive index of the grating area is less than 1.9, a high refractive index dielectric film needs to be covered on the surface of the grating to ensure diffraction efficiency. In addition, adding a layer of low refractive index film on the surface of the high refractive index film can improve the process tolerance and reduce the difficulty of processing.

In a possible implementation of the third aspect, the grating includes a plurality of grating lines, the plurality of grating lines are periodically arranged along an extension direction of the reflective surface, and a top surface and/or a side surface of at least one of the plurality of grating lines is covered with at least one layer of dielectric film.

In a possible implementation of the third aspect, the grating includes a plurality of grating grooves, the plurality of grating grooves are arranged at intervals along an extension direction of the reflection surface, and at least one of the plurality of grating grooves is covered with at least one dielectric film.

In a possible implementation of the third aspect, a sputtering or epitaxial process is used to form a dielectric film, but the process of forming a dielectric film is not limited thereto, and any process that can form a dielectric film on the grating surface falls within the protection scope of this application.

In a possible implementation of the third aspect, the material of the dielectric film includes any one or more of high-refractive-index dielectric materials such as TiO 2 , Ta 2 O 5 , SiO 2 or polymers.

In a possible implementation of the third aspect above, the material to be imprinted includes a liquid polymer material.

In a possible implementation of the third aspect, the material to be imprinted includes a sol material that can precipitate any one of ZrO 2 and SiO 2 at a set temperature.

It should be noted that the material to be imprinted is not limited to the above-mentioned liquid polymer material and sol material, but may also be other materials used for imprinting a grating structure on a substrate.

In a possible implementation of the third aspect above, the first part is an optical encoder; the material to be imprinted is set on the surface of the optical encoder; the set shape of the imprinting template is periodically arranged along the extension direction of the surface of the optical encoder; the second part is a grating scale, and the material to be imprinted forms a grating scale on the surface of the optical encoder after demolding.

The manufacturing method of the optical encoder of the embodiment of the present application shows that the manufacturing method provided by the embodiment of the present application can not only integrate the grating on the surface of the flat material to be imprinted, but also integrate the grating on the surface of the special-shaped material to be imprinted. In other words, the material to be imprinted by the grating can be a non-standard flat plate, prism, cylinder or other shape, and the surface combined with the grating can be a flat surface, or a non-flat surface such as a cylindrical surface or a spherical surface, which has a wider range of applications compared with the photolithography grating in the prior art.

In a possible implementation of the third aspect above, the set shape of the imprint template includes multiple first areas and multiple second areas, and the multiple first areas and the multiple second areas are arranged at intervals, and along the lateral direction perpendicular to the extension direction of the surface of the optical encoder, the top surface of the projected shape of the multiple first areas is higher than the top surface of the projected shape of the multiple second areas.

In a possible implementation of the third aspect, the surface roughness of the first region is greater than the surface roughness of the second region; or, the surface roughness of the first region is less than the surface roughness of the second region.

For example, if it is a transmissive optical encoder, the bright area needs to have high light transmittance, and at the same time, the dark area is contrasted with the bright area by means of shading through coating or forming a high-roughness matte surface, so that bright and dark areas appear alternately, so that when light passes through or reflects at the top (i.e., the gate line) or valley (i.e., the gate groove) of the periodic structure, a larger extinction ratio is formed.

In a possible implementation of the third aspect above, the grating scale includes a plurality of grating lines corresponding to the plurality of second regions, and a plurality of grating grooves corresponding to the plurality of first regions, the plurality of grating lines are periodically arranged along the extension direction of the surface of the optical encoder, and each of the plurality of grating grooves is arranged at intervals between adjacent grating lines.

In a possible implementation of the third aspect above, the gate line includes a first surface, and the gate groove includes a second surface; the first surface is a light-blocking area of the optical encoder, and the second surface is a light-transmitting area of the optical encoder, or the first surface is a light-transmitting area of the optical encoder, and the second surface is a light-blocking area of the optical encoder.

In a possible implementation of the third aspect, the surface of the optical encoder is any one of the upper and lower surfaces of a cuboid or a ring, a spherical surface, or the inner and outer surfaces of a cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram showing an application scenario of an optical communication network routing device;

FIG2 shows a schematic diagram of a wavelength selective switch;

FIG3 shows a schematic structural diagram of a wavelength selective switch provided in Embodiment 1 of the present application;

FIG4a shows a schematic structural diagram of a light splitting element provided in Embodiment 1 of the present application;

FIG4b shows another schematic structural diagram of the light splitting element provided in the first embodiment of the present application;

FIG5 shows a manufacturing process flow chart of an optical device provided in Example 1 of the present application, wherein FIG5(a) shows a manufacturing process flow chart 1 of the optical device, FIG5(b) shows a manufacturing process flow chart 2 of the optical device, and FIG5(c) shows a manufacturing process flow chart 3 of the optical device;

FIG6 shows a schematic structural diagram of a prism provided in Example 1 of the present application;

FIG. 7 is a partial enlarged schematic diagram of the E region in FIG. 4 a;

FIG8 is a schematic diagram showing the projection shape of the grating lines of the spectral element provided in the first embodiment of the present application, wherein FIG8 (a) shows that the projection shape of the grating lines is a sawtooth shape, FIG8 (b) shows that the projection shape of the grating lines is a triangle, and FIG8 (c) shows that the projection shape of the grating lines is a rectangle;

FIG9 shows a graph of wavelength-diffraction efficiency for different grating line projection shapes;

FIG10 is a schematic diagram showing various coverage conditions of the dielectric film of the spectroscopic element provided in the first embodiment of the present application on the grating surface, FIG10 (a) shows that the top surface of the grating line is covered with a dielectric film, FIG10 (b) shows that the bottom wall of the grating groove is covered with a dielectric film, FIG10 (c) shows that the top surface of the grating line and the bottom wall of the grating groove are simultaneously covered with a dielectric film, FIG10 (d) shows that the surface of the grating line and the grating groove is covered with a non-uniform dielectric film, and FIG10 (e) shows that the surface of the grating line and the grating groove is covered with multiple layers of dielectric films;

FIG11 shows a schematic structural diagram of an optical encoder provided in Embodiment 2 of the present application;

FIG12 shows another schematic diagram of the structure of an optical encoder provided in Embodiment 2 of the present application;

FIG13 is a partial enlarged schematic diagram of the F area in FIG7 and FIG8;

FIG14 shows another structural schematic diagram of an optical encoder provided in Embodiment 2 of the present application;

FIG15 shows a fourth structural schematic diagram of the optical encoder provided in Embodiment 2 of the present application;

FIG. 16 shows a manufacturing process flow chart of an optical device provided in Embodiment 2 of the present application, wherein (a) of FIG. 16 shows a manufacturing process flow chart of the optical device, (b) of FIG. 16 shows a manufacturing process flow chart of the optical device, and (c) of FIG. 16 shows a manufacturing process flow chart of the optical device. Process flow chart 3;

Figure 17 shows a schematic diagram of the distribution of bright and dark areas of the optical encoder provided in Example 2 of the present application. The optical encoder shown in (a) in Figure 17 forms a dark area on the top and a bright area on the bottom. The optical encoder shown in (b) in Figure 17 forms a bright area on the top and a dark area on the bottom.

DETAILED DESCRIPTION

An embodiment of the present application provides an optical device including a first part (such as the prism and optical encoder described later) and a second part (such as the grating and grating ruler described later). The first part is directly used as a substrate, and a second part with a periodic set shape is directly generated on the surface of the first part by an imprinting process, so as to form an optical device in an integrated manner.

It can be understood that the optical device provided in the embodiment of the present application includes a grating applied to a wavelength selection switch, but the embodiment of the present application is not limited to the grating, and can also be other optical devices, for example, an optical encoder used to accurately detect the motion state of a mechanical device.

The following embodiments of the present application are first introduced by taking the optical device as a prism as an example, the first part of the optical device is a prism, and the second part of the optical device is a grating. The embodiments of the present application directly use a prism as a substrate, coat the material to be imprinted (polymer material or glass material) on the reflective surface of the prism, and use an imprinting process to imprint and solidify the material to be imprinted on the reflective surface of the prism to form a periodic grating structure, thereby integrating the grating and the prism together to realize an integrated integrated prism solution, which can greatly improve the grating density based on existing equipment and processes. Compared with the prior art, the grating in the prism of the embodiment of the present application has a greater challenge to achieve a line density of 2000 lines/mm for the photolithography grating. The grating in the prism of the embodiment of the present application has better scalability. At the same time, the prism of the embodiment of the present application can avoid the reliability risk and yield loss introduced in the optical glue or bonding process, thereby improving the yield.

To facilitate understanding of the technical solution of the present application, some concepts or terms involved in the embodiments of the present application are first explained.

(1) Wavelength Selective Switch (WSS)

A wavelength switch is an optical module that can dispatch laser signals of different wavelengths from one or more input ports to one or more output ports in real time.

(2) Wavelength Division Multiplexing (WDM)

Wavelength division multiplexing refers to the technology of transmitting two or more optical signals of different wavelengths in the same optical fiber of an optical line.

(3) Refractive index

The refractive index of a medium refers to the ratio of the speed at which light waves propagate in a vacuum to the speed at which light waves propagate in the medium.

(4) Grating

A grating is an optical element whose surface is integrated with periodic structures such as rectangles, sinusoids, sawtooths, triangles or trapezoids. The number of periodic shapes per millimeter is called the line density of the grating. When light waves of a specific wavelength are reflected or transmitted on the surface of the grating, alternating light and dark stripes are produced. This phenomenon is called diffraction of light. Different bright stripes are called different orders. The ratio of the energy of the diffracted light to the input energy is called the diffraction efficiency. Light waves of different wavelengths produce bright or dark stripes at different positions and angles. This phenomenon is called dispersion of light. For every 1nm change in wavelength, the change in the light wave output angle is called the dispersion angle. A grating that uses the function of diffracting light waves is also called a diffraction grating.

(5) Prism

A prism refers to a block of dielectric material (glass, crystal material, polymer material, etc.) whose input surface is not parallel to the input surface. When a light wave penetrates the interface between the prism and the air, the propagation direction is deflected, which is called the refraction of light. When different wavelengths penetrate the prism at the same angle, the propagation directions are different. This phenomenon is also called the dispersion of light.

(6) Micro-Electro-Mechanical System (MEMS)

Micro-electromechanical systems (MEMS) refers to an industrial technology that integrates microelectronics with mechanical engineering. In this article, it refers to a reverse mirror array whose angle is controlled by voltage. Its function is to adjust the direction of light reflected after it hits each mirror in real time.

(7) Liquid Crystal On Silicon (LCOS)

Liquid crystal on silicon refers to a device in which the surface of an integrated circuit is polished with advanced technology and then coated with aluminum as a reflector to form an integrated circuit substrate. The integrated circuit substrate is then bonded to a glass substrate containing transparent electrodes, and liquid crystal is injected between the two substrates to form a package. The liquid crystal molecules will have different orientations under different electric fields, and thus have different refractive indices. The voltage and electric field applied to each unit between the glass substrate and the integrated circuit substrate can be controlled through the integrated circuit, thereby controlling the refractive index of the liquid crystal molecules in each unit, and then controlling the reflection angle and direction of the light incident on the unit.

(8) Grism

A grating is an optical element that integrates a grating and a prism to achieve an ultra-large dispersion angle.

(9) Insertion loss (IL)

Insertion loss refers to the energy loss of an optical signal when it passes through an interface, component or system. It is generally measured in dB and is defined as in formula 1.1: Where Pin is the input optical power and Pout is the output optical power;

Polarization extinction ratio: refers to the ratio of the energy of two perpendicular polarization components of a light signal, measured in dB, and defined as in formula 1.2, where Px is the energy of the polarization component in a specified direction, and Py is the energy of the polarization component in another direction perpendicular to Px.

The implementation methods of the present application will be further described in detail below in conjunction with the accompanying drawings.

FIG. 1 shows an application scenario of an optical communication network routing device.

Specifically, as shown in Fig. 1, there are multiple sites in the application scenario, such as site A, site B, site C, site D and local server 200 shown in Fig. 1. Optical signals of different wavelengths (as shown by λ ₀ , λ ₁ , λ ₂ and λ ₃ in Fig. 1) need to be distributed to different sites to complete the scheduling of signals of different wavelengths.

It should be noted that the application scenarios of the embodiments of the present application are not limited to the five sites shown in Figure 1 and the scheduling of optical signals of four different wavelengths. In some possible implementations, a corresponding number of sites can be set according to actual needs and the scheduling of optical signals of other numbers of wavelengths can be completed. For example, the optical communication network routing equipment includes six sites and needs to complete the scheduling of optical signals of five different wavelengths.

Exemplarily, the multiple sites represent city A, city B, city C, city D, and a local server of city A, respectively, and the multiple sites are connected via optical fibers for transmitting optical signals. For example, city B is connected to city A via optical fibers, city A is connected to city C via optical fibers, city A is connected to city D via optical fibers, and city A is connected to server 200 via optical fibers.

Referring to FIG. 2 , city A has a module capable of performing wavelength scheduling, namely, a wavelength selective switch 100 (WSS). When an optical signal λ ₀ (λ ₀ includes different wavelengths of λ ₁ , λ ₂ and λ ₃ ) is sent from city B to city A, the wavelength selective switch 100 of city A can distribute the optical signal λ ₀ with multiple different wavelengths from the input port (i.e., city B) into optical signals of different wavelengths (as shown by λ ₁ , λ ₂ and λ ₃ in FIG. 1 and FIG. 2 ), and schedule the optical signals of different wavelengths to the corresponding multiple output ports (i.e., the local server 200 of city A, city C, and city D) in real time according to the planned path. Among them, after the optical signal λ ₀ is sent from city B to city A through the optical fiber, after the real-time scheduling of the wavelength selective switch 100, the optical signal with wavelength λ ₁ is scheduled to the local server 200 of city A, and the optical signals with wavelengths λ ₂ and λ ₃ are scheduled to city C and city D respectively. Exemplarily, λ ₀ includes a light signal λ ₁ sent to the local server 200 of city A indicating a WeChat Chinese emoticon, a light signal λ ₂ sent to city C indicating access to a Baidu server, and a light signal λ ₃ sent to city D.

FIG3 shows a schematic diagram of the structure of a spectrometer using a grism 105 as a wavelength selective switch 100 provided in an embodiment of the present application. However, the spectrometer in the embodiment of the present application is not limited to a grism, but may also be other optical devices, such as a grating or a prism.

As shown in Fig. 3, the wavelength selective switch 100 provided in the embodiment of the present application includes an optical fiber array 101, a lens array 102, a first reflector 103, a grism 105, and a second reflector 104. A single multi-wavelength optical signal (such as the multi-wavelength optical signal λ ₀ mentioned above) enters the lens array 102 from the input port 106 in the optical fiber array 101 and is output to the first reflector 103. After being reflected by the first reflector 103, it is transmitted to the grism 105, and after being dispersed and expanded by the grism 105, it is divided into a plurality of single-wavelength optical signals, which are transmitted to the second reflector 104. After being reflected, the plurality of single-wavelength optical signals are dispersed and folded by the grism 105, and then the light spot shape and transmission direction are adjusted by the reflector 103 and the lens array 102, and finally sent to a specific output port 107 in the optical fiber array 101.

Specifically, the optical fiber array 101 is used to arrange optical fibers containing input signals and output signals (i.e., the optical fiber connected to the input port 106 and the optical fiber connected to the output port 107 shown in FIG. 3 ) in a certain order and distance (i.e., one input port 106 and four output ports 107 are arranged at intervals as shown in FIG. 3 ), one end of which is connected to an external system (e.g., the city B shown in FIG. 1 ) through an optical connector, and the other end of which inputs a laser signal (i.e., a multi-wavelength optical signal λ ₀ ) to a wavelength selective switch 100 (e.g., the city A shown in FIG. 1 ).

Exemplarily, the optical fiber array 101 adopts a V-groove or hole structure made of glass or silicon, so that the optical fibers of the optical fiber array 101 are fixed in the V-groove or hole structure. The lens array 102 is composed of five lenses corresponding to one input port 106 and four output ports 107, and the purpose is to adjust the light spot emitted from the optical fiber of the input port 106 or the reflected light spot from the first reflector 103 to a light spot shape and energy distribution that meet the system requirements, that is, to convert the divergent light into collimated light.

Exemplarily, the lens array 102 includes a double-sided lens and a single-sided lens, and the material of the lens includes silicon, glass or polymer materials, etc. The embodiment of the present application does not specifically limit the shape and number of the lenses. In actual applications, according to system requirements, the shape of the lens can be round or square, and the surface shape of the lens can be spherical, cylindrical, ellipsoidal or other aspherical surfaces, etc.

The first reflector 103 can change the direction of light transmission to transmit the light passing through the lens array 102 to the prism 105. At the same time, the first reflector 103 can fine-tune the reflection direction of light at different positions (for example, multiple single-wavelength light signals after dispersion and folding by the prism 105) to compensate for the optical distortion caused by different optical paths.

In the above-mentioned second reflector 104, the reflector surface is divided into different pixel points, and each pixel point can independently control its reflection direction. After the single multi-wavelength optical signal λ ₀ from the input port 106 is dispersed by the grating 105, the laser spots of multiple single-wavelength optical signals (i.e., λ ₁ , λ _2, and λ ₃ shown in FIG. 1 ) will fall on different positions of the second reflector 104 (i.e., corresponding to the pixel points on the second reflector 104), and the second reflector 104 controls the reflection directions of the single-wavelength optical signals at different positions according to the optical fiber arrangement position of the output port 107 in the optical fiber array 101, so that the reflected single-wavelength optical signals (i.e., λ ₁ , λ ₂ , and λ ₃ shown in FIG. 1 ) are dispersed and folded by the light splitting device 105, and then the spot shape and transmission direction are adjusted by the reflector 103 and the lens array 102, and finally sent to the optical fiber array 101 arranged in sequence, for example, according to the λ ₁ , λ ₂ , and λ 3 shown in FIG. 3 . ₃ to complete the wavelength scheduling.

Exemplarily, the second reflector 104 includes a MEMS reflector or an LCOS reflector, wherein the MEMS reflector adjusts the angle of the mirror by adjusting the driving voltage of each unit (i.e., corresponding to the above-mentioned pixel point) to achieve the purpose of controlling the reflection direction; and the LCOS controls the driving voltage of each unit (i.e., corresponding to the above-mentioned pixel point) to adjust the orientation of the liquid crystal molecules of the unit, thereby controlling its refractive index to achieve the purpose of controlling the reflection direction.

The specific structure of the grating 105 in the wavelength selective switch 100 will be further described below with reference to the accompanying drawings.

Please refer to FIG. 4a and FIG. 4b. FIG. 4a shows a first schematic diagram of the structure of the grism 105, and FIG. 4b shows a second schematic diagram of the structure of the grism 105. The grisms 105 shown in FIG. 4a and FIG. 4b both include a prism area 120 (including a prism 111) and a grating area 121 (including a grating 110). The grism 105 in FIG. 4a includes an input surface 123, an output surface 123, and a reflection surface 124. The input surface 123 and the output surface 123 are located on the same side of the grism 105, and the reflection surface 124 is not parallel to the input surface 123 (FIG. 4a shows an approximately vertical relationship, and the reflection surface 124 and the input surface 123 are arranged at an angle of 85°, 86°, 87°, 90°, 90.1°, etc.). The prism 105 shown in FIG4b also includes an input surface 125, an output surface 126 and a reflection surface 124, wherein the input surface 125 and the output surface 126 are located on two different intersecting sides of the prism 105, and the reflection surface 124 and the input surface 125 are also not parallel to each other (as shown in FIG4b, they are approximately perpendicular to each other).

As shown in Fig. 4a and Fig. 4b, the input surfaces 123 and 125 of the prism 105 are used for inputting optical signals (e.g., λ ₀ ), and the reflective surface 124 is used for dispersing the optical signals from the input surfaces 123 and 125 to generate multiple single-wavelength optical signals (e.g., λ ₁ , λ ₂ and λ ₃ ), and then transmitting them to the output surface, such as the output surface 123 in Fig. 4a , or the output surface 126 shown in Fig. 4b . Exemplarily, the material of the prism 111 in the embodiment of the present application includes glass, transparent silicon or polymer material, etc.

In the embodiment of the present application, the grating 110 in the spectroscopic device shown in FIG. 4 a and FIG. 4 b is formed by imprinting and curing the material to be imprinted on the reflection surface 124 of the prism 111 .

The following will be combined with FIG. 5 and FIG. 6 to illustrate an example of the process flow of forming the grating 110 on the surface of the prism 111 in the embodiment of the present application:

As shown in (a) to (c) of FIG. 5 , the method for manufacturing the grism provided in the embodiment of the present application specifically comprises the following steps:

S1: Provide a prism 111.

First, the prism 111 is fixed by a clamp, and the prism 111 serves as a substrate. Referring to FIG. 6 , the prism 111 includes an input surface (such as the input surface 123 described above) and a reflection surface 124 that are not parallel to each other.

Exemplarily, the prism 111 is an optical passive component manufactured by a processing technology. Exemplarily, the prism 111 can be a glass or silicon optical passive component manufactured by a mechanical processing technology such as grinding and polishing, or a polymer optical passive component manufactured by a process such as injection molding or molding. The input surface 123 and the reflection surface 124 of the prism 111 are coated with an anti-reflection film to reduce end face reflection.

S2: placing a material to be imprinted on the surface of the prism 111 .

Referring to FIG. 5( a ), the prism 111 is used as a substrate, and a material to be imprinted 131 is disposed on the reflective surface 124 of the prism 111. Exemplarily, the material to be imprinted 131 of the embodiment of the present application includes a liquid polymer material (e.g., a heat-cured/ultraviolet-cured polymer material), but the material to be imprinted 131 of the embodiment of the present application is not limited to a polymer material, and may also be other materials to be imprinted, for example, the material to be imprinted 131 also includes a sol material capable of precipitating any one of ZrO2 and SiO2 at a set temperature.

Exemplarily, the polymer material selected for the material to be imprinted refers to a synthetic resin that undergoes a polymerization reaction under heating or under the action of ultraviolet light, and cross-links and solidifies into an insoluble and infusible substance. Exemplarily, the synthetic resin includes phenol, epoxy, amino, and polyacrylate, etc. The material has a high transmittance in the visible light and near-infrared bands, and a refractive index between 1.4 and 1.8.

If two sol materials containing Zr, Si and O are selected, a chemical reaction is carried out at a certain temperature (within 500°C, such as 350°C, 400°C, 500°C) after subsequent imprinting and molding, and inorganic substances such as ZrO2 or SiO2 are precipitated and deposited on the surface of the prism 111 to form the grating 110 structure, and the organic matter is volatilized.

S3: Using the imprint template 130 with a set shape to imprint the material 131 to be imprinted, the set shape is along the reflection surface of the prism 111 The extending direction of 124 (as shown in the X direction in FIG. 5 ) is parallel to the direction and is periodically arranged.

Referring to FIG. 5(b), after the upper surface of the prism 111 (i.e., the reflective surface 124) is coated with the liquid polymer material before curing (i.e., the material to be imprinted 131), the imprinting template 130 engraved with a shape complementary to the grating 110 (as shown in FIG. 5(c)) is pressed onto the surface of the prism 111 coated with the polymer material (i.e., the material to be imprinted 131) to complete the imprinting (e.g., a nanoimprinting process). Exemplarily, the imprinting direction is along the direction perpendicular to the reflective surface 124 (as shown in the Y direction in FIG. 5), wherein the set shape of the imprinting template 130 is periodically arranged along the direction parallel to the extension direction of the reflective surface 124 (as shown in the X direction in FIG. 5(b)). Exemplarily, the periodic structure of the imprinting template 130 is a trapezoidal structure. Correspondingly, the periodic structure of the grating 110 formed subsequently is also a trapezoidal structure. That is, the periodic structure of the grating 110 depends on the periodic structure of the imprinting template 130.

Exemplarily, the material of the imprint template 130 includes any one of silicon, glass, metal or polymer material, and the imprint template 130 can achieve a periodically arranged set shape (such as the periodic trapezoidal shape shown in (a) of FIG. 5 ) through DUV/EBL lithography or high-precision single-point diamond machining.

S4 : curing and demolding the imprinted material 131 to form a grating 110 on the surface of the prism 111 .

Referring to FIG. 5( c ), after the imprinting is completed by pressing the imprint template 130 onto the reflective surface 124 of the prism 111 coated with the material to be imprinted 131, curing is further completed, and the imprint template 130 is separated from the reflective surface 124 of the prism 111, and the cured shape of the grating 110 is left on the reflective surface 124 of the prism 111. In other words, after the material to be imprinted 131 is demolded, the grating 110 is formed on the reflective surface 124 of the prism 111, and the grating 110 and the prism 111 are integrated into the grism 105.

Refer to Figure 7, which is an enlarged view of part E in Figure 4a. As shown in Figure 7, there is only one interface between the prism 111 and the grating 110 in the grating 105 after the stamping, and the interface is the reflection surface 124 of the prism 111. Exemplarily, the curing conditions of the above-mentioned polymer vary depending on the material, and can be thermal curing, ultraviolet curing, or curing after the sol undergoes a chemical reaction.

In summary, the process of forming the grating 110 from the grating 105 in the embodiment of the present application does not use a photolithography process or an optical glue or bonding process, so that the grating shape can be finely controlled, the line density can be improved, and the problem of low yield when the grating and the prism are glued together in the optical glue or bonding process can be avoided. In addition, the grating 110 in the embodiment of the present application is integrated with the prism 111 through an integrated integration solution to form an integrated grating. It can greatly improve the grating density based on existing equipment and processes, has better scalability, avoids the reliability risk and yield loss introduced in the optical glue or bonding process, and improves the yield.

In the integrated prism 105, the prism 111 plays a certain role in dispersion expansion, which is superimposed on the dispersion effect of the grating area 121 to form an overall dispersion capability of the prism 105 to achieve a larger dispersion angle, thereby shortening the distance between the first reflector 103 and the second reflector 104 and the spectrometer 105 in the internal structure of the wavelength selective switch 100, so that the first reflector 103 and the second reflector 104 are closer to the spectrometer 105, thereby reducing the size of the wavelength selective switch 100.

In addition, after the optical signal is dispersed by the grating 105, it will fall on different positions of the second reflector 104. When the dispersion angle of the grating 105 is larger, the spacing between different positions on the second reflector 104 is larger, which helps to reduce signal crosstalk between optical signals of adjacent wavelengths and affects the signal transmission between optical signals of adjacent wavelengths.

As shown in FIG7 , the grating 110 includes a plurality of grating lines 1101, which are periodically arranged along the extension direction (as shown in the X direction in FIG7 ) of the reflection surface 124. The grating 110 also includes a plurality of grating grooves 1102 (a concave portion of the grating 110 on the side facing away from the reflection surface 124), which are spaced apart along the extension direction (as shown in the X direction in FIG7 ) of the reflection surface 124.

It can be understood that the number of periodic shapes per millimeter is expressed as the grating density of the grating. In the prior art, due to the influence of the large-area light field uniformity and resolution of the grating etching process, the grating density is difficult to reach more than 2000 lines/mm. Since in the embodiment of the present application, the grating is formed by the process of stamping and curing, by designing the periodic structure of the stamping template 130, the grating density (i.e., the density of the grating lines 1101) can reach 20,000 lines/mm. The grating density will directly affect the dispersion angle of the grating. The larger the grating density, the larger the dispersion angle of the grating, and the higher the overall dispersion ability of the prism.

Exemplarily, along the lateral direction perpendicular to the extension direction (as shown in the X direction in FIG. 7 ), the grating line projection shape of the plurality of grating lines 1101 is a trapezoidal structure. However, the embodiment of the present application does not limit the grating line projection shape of the grating lines 1101, and the periodic structure of the imprint template 130 can be adjusted according to different application scenarios and optical path designs to adjust the grating line projection shape of the plurality of grating lines 1101 of the prism in the embodiment of the present application.

For example, in some possible embodiments, referring to (a), (b) and (c) in FIG8 , the grid line projection shapes include a sawtooth shape (as shown in (a) in FIG8 ), a triangle (as shown in (b) in FIG8 ), and a rectangle (as shown in (c) in FIG8 ).

FIG9 shows a schematic diagram of diffraction efficiency curves for different grating line projection shapes for different wavelengths. Among them, the grating line projection shape corresponding to curve a is a sawtooth shape, the grating line projection shape corresponding to curve b is a triangle, and the grating line projection shape corresponding to curve c is a rectangle. It can be seen from FIG9 that the bandwidth of curve a is smaller than the bandwidth of curve b, and the bandwidth of curve b is smaller than the bandwidth of curve c; the diffraction efficiency of curve a is greater than the diffraction efficiency of curve b, and the diffraction efficiency of curve b is greater than the diffraction efficiency of curve c.

It can be seen from this that when the wavelength range (i.e., bandwidth) to be covered is wider, the grating line projection shape of the multiple grating lines 1101 of the grating in the embodiment of the present application can be adjusted to a rectangular or trapezoidal shape. When a higher diffraction efficiency is required at a single wavelength, the grating line projection shape of the multiple grating lines 1101 of the grating in the embodiment of the present application can be adjusted to a triangular or sawtooth shape.

In some possible implementations, referring to FIG7 , the prism 105 provided in the embodiment of the present application is composed of a prism region 120, a grating region 121, and a dielectric film region 122. That is, a dielectric film is covered on the surface of the grating 110. Exemplarily, the material of the dielectric film includes any one or more of TiO2, Ta2O5, and SiO2.

It can be understood that the dielectric film area 122 is a high refractive index dielectric film structure attached to the surface of the grating 110 structure, and the actual reflection area of the laser signal occurs at the interface between the dielectric film and the grating area 121 and the interface between the dielectric film and the air. The laser signal is reflected at the interface between the dielectric film and the air. When the incident angle and the emission angle satisfy the following relationship, the reflected light at different positions coherently constructively appears, and bright fringes appear, that is, more energy is emitted from this direction.
mλ＝d(sinα+sinβ)

Wherein, m is the diffraction order (or spectral order), λ is the wavelength of the incident light, d is the spacing between the grating grooves 1102 of the grating 110 structure, α is the incident angle, and β is the emission angle.

It should be noted that in the embodiment of the present application, when the refractive index of the grating region 121 is greater than 1.9, it is not necessary to plate a dielectric film on the surface of the grating 110. When the refractive index of the grating region 121 is less than 1.9, it is necessary to cover the surface of the grating 110 with a dielectric film of high refractive index to ensure diffraction efficiency. In addition, adding a layer of low refractive index film on the surface of the high refractive index film can improve the process tolerance and reduce the difficulty of processing.

In addition, the embodiment of the present application does not limit the specific form of the dielectric film covering the surface of the grating 110.

In some possible implementations, referring to (a) to (e) in FIG. 10 , the top surface and/or side surface (i.e., the side wall of the gate groove 1102) of at least one of the plurality of gate lines 1101 is covered with at least one dielectric film. Also, at least one gate groove 1102 (i.e., the bottom wall of the gate groove 1102) of the plurality of gate lines 1101 is covered with at least one dielectric film. Continuing to refer to FIG. 7 , along the direction perpendicular to the reflective surface 124 (as shown in the Y direction in FIG. 7 ), the distance between the bottom surface 11021 of the gate groove 1102 and the reflective surface (as shown in h in FIG. 7 ) is less than 100 microns.

Exemplarily, as shown in (a) of FIG. 10 , the top surface of the gate line 1101 is covered with a layer of dielectric film; as shown in (b) of FIG. 10 , the bottom wall of the gate groove 1102 is covered with a layer of dielectric film; as shown in (c) of FIG. 10 , the top surface of the gate line 1101 and the bottom wall of the gate groove 1102 are simultaneously covered with a layer of dielectric film; as shown in (d) of FIG. 10 , the surfaces of the gate line 1101 and the gate groove 1102 are covered with a layer of non-uniform dielectric film; as shown in (e) of FIG. 10 , the surfaces of the gate line 1101 and the gate groove 1102 are covered with multiple layers of dielectric films, such as a first layer of dielectric film 1221 covering the surface of the grating and a second layer of dielectric film 1222 covering the first layer of dielectric film 1221.

Referring to Figures 11 to 15, in some application scenarios, such as the moving parts of some mechanical equipment (such as vehicle-mounted radars, machine tools, etc.), in order to accurately detect the motion state (including motion direction, motion speed and acceleration, displacement, etc.), an optical encoder is required. The optical encoder is distributed with bright and dark areas with different reflection or transmission properties of light. When the light emitted by the light source 142 enters the light detector 143 after being transmitted or reflected by the optical encoder, it will affect the strength of the signal received by the detector. The light detector 143 can calculate the motion state of the encoder (including speed, direction, displacement, etc.) by combining the corresponding algorithm, and can obtain accurate motion information by identifying and analyzing the brightness changes of the received light. That is, the light detector 143 can obtain accurate motion information by identifying and analyzing the brightness changes of the received light.

The specific structure of the optical encoder will be further described below in conjunction with the accompanying drawings.

In some possible embodiments, referring to FIG. 11 , the optical device provided in the embodiment of the present application includes a first optical encoder 150 (the first part of the optical device) and a first grating scale 151 (the second part of the optical device). The first grating scale 151 is formed by imprinting and curing the material to be imprinted on the surface of the first optical encoder 150.

It can be understood that the light emitted by the light source 142 is transmitted through the grating scale 151 of the first optical encoder 150 and then enters the light detector 143. The light detector 143 obtains accurate motion information by identifying and analyzing the brightness changes of the received light. Exemplarily, referring to FIG11, the first optical encoder 150 is a transmissive circular optical encoder, that is, the detection method of the first optical encoder 150 is transmissive, but the embodiment of the present application is not limited to a transmissive optical encoder, and other detection methods can also be used.

For example, referring to FIG. 12 , in some possible implementations, the second optical encoder 152 is a reflective circular optical encoder, and the light emitted by the light source 142 is reflected by the second grating scale 153 of the second optical encoder 152 and then enters the light detector 143 .

In some possible embodiments, referring to Figure 13 and in combination with Figures 11 and 12, the first grating scale 151 and the second grating scale 153 each include a plurality of grating lines 1101 (i.e., protrusions extending outward along a surface perpendicular to the optical encoder in Figure 13) and a plurality of grating grooves 1102, the plurality of grating lines 1101 are periodically arranged along an extension direction of the surface of the optical encoder (as shown in the R direction in Figure 13), and each of the plurality of grating grooves 1102 is arranged at intervals between adjacent grating lines 1101.

Exemplarily, referring to FIG. 11 and FIG. 12 , the shape of the first optical encoder 150 includes a spherical shape or a cylindrical shape, but the embodiments of the present application are not limited thereto, and the optical encoder may also be in other shapes.

For example, referring to FIG. 14 , in some possible implementations, the third optical encoder 154 is a transmissive disc optical encoder, and the light emitted by the light source 142 is transmitted through the third grating scale 155 of the third optical encoder 154 and then enters the light detector 143 .

And, referring to FIG. 15 , in some possible implementations, the fourth optical encoder 156 is a transmissive bar optical encoder, and the light emitted by the light source 142 is transmitted through the fourth grating scale 157 of the fourth optical encoder 156 and then enters the light detector 143 .

It can be understood that according to the motion characteristics of the moving parts (circular motion or linear motion), the shape of the optical encoder can be designed to be any one of the above-mentioned spherical, cylindrical, rectangular and annular shapes, and the transmission or reflection detection method can also be adapted and selected according to the system requirements.

The following will be combined with FIG. 16 to illustrate an example of the process flow of forming a grating scale on the surface 1411 of the base 141 of the optical encoder in the embodiment of the present application:

As shown in (a) to (c) of FIG. 16 , the manufacturing method of the optical encoder provided in the embodiment of the present application specifically includes the following steps:

S1: Provides optical encoder.

First, the optical encoder is fixed by a clamp. The optical encoder includes a base 141. The base 141 of the optical encoder serves as a substrate.

S2: Arrange the material to be imprinted on the surface of the optical encoder.

Referring to FIG. 16 (a), the base 141 of the optical encoder is used as a substrate, and the material to be imprinted 131 is set on the surface 1411 of the base 141 of the optical encoder. The surface 1411 of the base 141 of the optical encoder includes any one of the upper and lower surfaces of a cuboid or a ring, a spherical surface, or the inner and outer surfaces of a cylinder. Exemplarily, the material to be imprinted 131 of the embodiment of the present application includes a liquid polymer material, but the material to be imprinted 131 of the embodiment of the present application is not limited to a polymer material, and can also be other materials to be imprinted. For example, the material to be imprinted 131 also includes a sol material that can precipitate any one of ZrO2 and SiO2 at a set temperature.

It is understood that the polymer material selected for the material to be imprinted refers to a synthetic resin that undergoes polymerization reaction under heating or ultraviolet light, cross-links and solidifies into an insoluble and infusible substance. For example, the synthetic resin includes phenol, epoxy, amino and polyacrylate, etc. The material has a high transmittance in the visible light and near-infrared bands, and the refractive index is between 1.4 and 1.8.

If two sol materials containing Zr, Si and O are selected, a chemical reaction is carried out at a certain temperature (within 500°C, such as 350°C, 400°C, 500°C) after subsequent embossing, and inorganic substances such as ZrO2 or SiO2 are precipitated and deposited on the surface 1411 of the base 141 of the optical encoder to form a grating scale structure, and the organic matter is volatilized.

S3: Imprint the material 131 to be imprinted using an imprint template 130 having a set shape, wherein the set shape is periodically arranged in a direction parallel to the extension direction of the base 141 of the optical encoder (as shown in the X direction in FIG. 16 ).

After the surface of the base 141 of the optical encoder (i.e., the surface where the light emitted by the light source 142 is transmitted or reflected, such as a strip surface or a disc surface) is coated with the liquid polymer material (i.e., the material to be imprinted 131) before curing, the imprinting template 130 engraved with a shape complementary to the grating scale (as shown in (c) in FIG. 16) is pressed onto the surface of the base 141 of the optical encoder coated with the polymer material (i.e., the material to be imprinted 131) to complete the imprinting. Among them, the set shape of the imprinting template 130 is periodically arranged along a direction parallel to the extension direction of the base 141 of the optical encoder (as shown in the X direction in FIG. 16 (b)). Exemplarily, the periodic structure of the imprinting template 130 is a trapezoidal structure.

Exemplarily, the material of the imprint template 130 includes silicon, glass and metal, and the periodically arranged set shape is realized by DUV/EBL lithography or high-precision single-point diamond machining.

S4: The imprinted material 131 is cured and demolded to form a grating scale on the surface of the base 141 of the optical encoder.

Referring to (c) in FIG. 16 , after the imprinting template 130 is pressed onto the surface 1411 of the base 141 of the optical encoder coated with the material to be imprinted 131 to complete the imprinting (for example, using a nanoimprinting process), the curing is further completed, and the imprinting template 130 is separated from the surface 1411 of the base 141 of the optical encoder, and the cured grating scale shape is left on the surface 1411 of the base 141 of the optical encoder. In other words, after the material to be imprinted 131 is demolded, a grating scale is formed on the surface of the base 141 of the optical encoder, and the grating scale and the optical encoder are integrated into a new optical device (i.e., a new integrated optical encoder with a grating scale). As shown in FIG. 16 , there is only one interface between the grating scale after imprinting (i.e., the material to be imprinted 131 after imprinting and curing) and the surface 1411 of the base 141 of the optical encoder, and the interface is the surface 1411 of the base 141 of the optical encoder.

Exemplarily, the curing conditions of the polymer described above vary depending on the material, and may be thermal curing, ultraviolet curing, or curing after a chemical reaction of the sol.

In summary, the process of forming a grating scale on the surface 1411 of the base 141 of the optical encoder in the embodiment of the present application does not use photolithography, photo-gluing or bonding processes, so that the shape of the grating scale can be finely controlled, the line density can be improved, and the problem of low yield when the optical encoder and the grating scale are glued together in the photo-gluing or bonding process can be avoided.

In addition, the grating ruler of the embodiment of the present application is integrated with the optical encoder through an integrated integration solution to form an integrated optical encoder. It can greatly improve the linear density of the grating ruler based on the existing equipment and process, has better scalability, avoids the reliability risk and yield loss introduced in the optical glue or bonding process, and improves the yield.

In other words, the manufacturing process of optical encoders that use nanoimprinting to imprint alternating light and dark structures and areas on the surface of moving strip, disk or wheel optical encoders can significantly reduce costs compared to traditional magnetic encoding processes, while the detection resolution can be improved to below sub-micron.

The manufacturing method provided in the embodiment of the present application can integrate the grating ruler not only on the surface of the flat material to be imprinted, but also on the surface of the special-shaped material to be imprinted. In other words, the material to be imprinted by the grating ruler can be a non-standard flat plate, prism, cylinder or other shape, and the surface combined with the grating ruler can be a flat surface, or a non-flat surface such as a cylindrical surface or a spherical surface, which has a wider range of applications compared with the photolithography grating ruler in the prior art.

In some possible embodiments, referring to (c) in FIG. 16 and in combination with (a) and (b) in FIG. 17 , the set shape of the imprint template 130 for preparing the optical encoder provided in the embodiment of the present application includes a plurality of first regions 1103 and a plurality of second regions 1104, and the plurality of first regions 1103 and the plurality of second regions 1104 are arranged at intervals, and along the lateral direction perpendicular to the extension direction of the surface of the base 141 of the optical encoder (as shown in the X direction in FIG. 16 (c)), the top surface of the projected shape of the plurality of first regions 1103 is higher than the top surface of the projected shape of the plurality of second regions 1104.

In some possible implementations, referring to (c) in FIG. 16 , the surface roughness of the first region 1103 is less than the surface roughness of the second region 1104. Thus, the first region 1103 can be embossed with a light-blocking region or a diffuse reflection region of the grating ruler, and the second region 1104 can be embossed with a light-transmitting region or a light-reflecting region of the grating ruler.

Alternatively, in some other embodiments, the surface roughness of the first region 1103 is less than that of the second region 1104. Thus, the first region 1103 can be embossed with a light-transmitting region or a light-reflecting region of a grating, and the second region 1104 can be embossed with a light-blocking region or a diffuse reflection region of a grating.

In some embodiments, referring to (a) and (b) in FIG. 17 and in combination with (c) in FIG. 16, the grating scale for preparing the optical encoder provided in the embodiment of the present application includes a plurality of grating lines 1101 corresponding to the plurality of second regions 1104, and a plurality of grating grooves 1102 corresponding to the plurality of first regions, the plurality of grating lines 1101 are periodically arranged along the extension direction of the surface 1411 of the base 141 of the optical encoder (as shown in the X direction in (a) and (b) in FIG. 16), and each of the plurality of grating grooves 1102 is arranged at intervals between adjacent grating lines 1101. Continuing to refer to FIG. 17, along the direction perpendicular to the reflection surface 124 (as shown in the Y direction in FIG. 17), the distance between the bottom surface of the grating groove 1102 and the surface 1411 of the base 141 of the optical encoder (as shown in m and n in FIG. 17) is less than 100 microns.

In some embodiments, referring to FIG. 17 (a), the gate line 1101 includes a first surface (i.e., a dark area 144), and the gate groove 1102 includes a second surface (i.e., a bright area 145); the first surface is a light-blocking area of the optical encoder, and the second surface is a light-transmitting area of the optical encoder. That is, the optical encoder shown in FIG. 17 (a) forms a dark area 144 (i.e., a light-blocking area or a diffuse reflection area) at the top of the periodic structure or a bright area 145 (i.e., a light-transmitting area or a light-reflecting area) at the bottom.

For example, if it is a translucent optical encoder, the bright area 145 needs to have high light transmittance, and at the same time, the dark area 144 is contrasted with the top by means of coating shading or forming a high-roughness matte surface, so that the bright area 145 and the dark area 144 appear alternately, so that when the light passes through or reflects at the top (i.e., the gate line 1101) or the valley (i.e., the gate groove 1102) of the periodic structure, a larger extinction ratio is formed.

Alternatively, in some other embodiments, referring to (b) in FIG. 17 , the first surface (i.e., the bright area 145) is the light-transmitting area of the optical encoder, and the second surface (i.e., the dark area 144) is the light-blocking area of the optical encoder. That is, the optical encoder shown in (b) in FIG. 17 forms a dark area 144 (i.e., a light-blocking area or a diffuse reflection area) at the bottom of the periodic structure or a bright area 145 (i.e., a light-transmitting area or a light-reflecting area) at the top.

In summary, the embodiment of the present application directly imprints and solidifies the material to be imprinted on the reflective surface of the prism to form a grating, thereby integrating the grating and the prism together to realize an integrated prism grating solution, which can greatly improve the grating density based on existing equipment and processes, has better scalability, avoids the reliability risk and yield loss introduced in the optical glue or bonding process, and the yield can be increased from 60% to more than 90%. Or the grating ruler is integrated on the surface of the optical encoder, which has a wider range of applications compared with the photolithography grating ruler in the prior art.

Claims (29)

An optical device, comprising: Part I; The second part is a periodic structure formed by processing the material to be processed disposed on the surface of the first part. There is only one interface between the first part and the second part, and the interface is the surface of the first part. The optical device according to claim 1 is characterized in that the side of the second part facing away from the interface comprises a recess, and along a direction perpendicular to the interface, the distance between the bottom surface of the recess and the interface is less than 100 microns. The optical device according to claim 1 is characterized in that the material to be processed is a material to be imprinted, and the second part is a periodic structure formed by imprinting and curing the material to be imprinted arranged on the surface of the first part. The optical device according to any one of claims 1 to 3, characterized in that The first part is a prism, and the prism includes an input surface and a reflection surface that are not parallel to each other, and the input surface is used for inputting optical signals; The second part is a grating, and the grating is formed by processing the material to be processed arranged on the reflection surface. The optical device according to claim 3, characterized in that the grating density of the grating is between 2000 lines/mm and 20000 lines/mm. The optical device according to claim 4 or 5 is characterized in that the grating includes a plurality of grating lines, and the plurality of grating lines are periodically arranged along the extension direction of the reflecting surface, and along the lateral direction perpendicular to the extension direction, the grating line projection shapes of the plurality of grating lines include any one or more of a trapezoid, a rectangle, a sawtooth, and a triangle. The optical device according to any one of claims 4 to 6, characterized in that the surface of the grating is partially or completely covered with at least one layer of dielectric film. The optical device according to claim 7 is characterized in that the grating includes a plurality of grating lines, the plurality of grating lines are periodically arranged along the extension direction of the reflecting surface, and the top surface and/or side surface of at least one of the plurality of grating lines is covered with at least one layer of dielectric film. The optical device according to claim 7 or 8 is characterized in that the grating comprises a plurality of grating grooves, the plurality of grating grooves are arranged at intervals along the extension direction of the reflecting surface, and at least one of the plurality of grating grooves is covered with at least one layer of dielectric film. The optical device according to any one of claims 1 to 3, characterized in that The first part is an optical encoder; The second part is a grating scale, and the grating scale is formed by processing the material to be processed which is arranged on the surface of the optical encoder. The optical device according to claim 10 is characterized in that the grating scale comprises a plurality of grating lines and a plurality of grating grooves, the plurality of grating lines are periodically arranged along the extension direction of the surface of the optical encoder, and each of the plurality of grating grooves is arranged at intervals between adjacent grating lines. The optical device according to claim 11 is characterized in that the grating lines include a first surface, and the grating grooves include a second surface; the first surface is a light-blocking area of the optical encoder, and the second surface is a light-transmitting area of the optical encoder, or the first surface is a light-transmitting area of the optical encoder, and the second surface is a light-blocking area of the optical encoder. The optical device according to any one of claims 9 to 12 is characterized in that the surface of the optical encoder includes any one of the upper and lower surfaces of a cuboid or a ring, a spherical surface, or the inner and outer surfaces of a cylinder. A wavelength selective switch, characterized by comprising the optical device according to any one of claims 1-9. A method for manufacturing an optical device, characterized in that the manufacturing method comprises: Provide the first part; Disposing a material to be imprinted on a surface of the first portion; Imprinting the material to be imprinted using an imprint template having a set shape, wherein the set shape is periodically arranged along a direction parallel to an extension direction of the surface of the first part; The embossed material is cured and demolded to form a second part on the surface of the first part, and there is only one interface between the first part and the second part, and the interface is the surface of the first part. The manufacturing method according to claim 15 is characterized in that the side of the second part facing away from the interface comprises a recess, and along a direction perpendicular to the interface, the distance between the bottom surface of the recess and the interface is less than 100 microns. The manufacturing method according to claim 16, characterized in that, The first part is a prism, and the prism includes an input surface and a reflection surface that are not parallel to each other; The surface of the first part includes the reflective surface, and the material to be imprinted is arranged on the reflective surface; The set shapes of the imprint template are periodically arranged along a direction parallel to the extension direction of the reflective surface; The second part is a grating, and the material to be imprinted forms the grating on the reflection surface of the prism after demolding. The manufacturing method according to claim 17 is characterized in that the grating density of the grating formed after printing and curing is between 2000 lines/mm and 20000 lines/mm. The manufacturing method according to claim 17 or 18 is characterized in that the grating formed after printing and curing includes a plurality of grating lines, and the plurality of grating lines are periodically arranged along the extension direction of the reflecting surface, and along the lateral direction perpendicular to the extension direction, the grating line projection shapes of the plurality of grating lines include any one or more of a trapezoid, a rectangle, a sawtooth, and a triangle. The manufacturing method according to any one of claims 17 to 19 is characterized in that the curing includes any one of thermal curing, UV curing, moisture absorption curing or thermoplastic curing. The manufacturing method according to any one of claims 17 to 20 is characterized in that at least one dielectric film is partially or completely covered on the surface of the grating. The manufacturing method according to any one of claims 17 to 21 is characterized in that the grating comprises a plurality of grating lines, the plurality of grating lines are periodically arranged along the extension direction of the reflecting surface, and the top surface and/or side surface of at least one of the plurality of grating lines is covered with at least one layer of dielectric film. The manufacturing method according to any one of claims 17 to 22 is characterized in that the grating comprises a plurality of grating grooves, the plurality of grating grooves are arranged at intervals along the extension direction of the reflecting surface, and at least one of the plurality of grating grooves is covered with at least one layer of dielectric film. The manufacturing method according to claim 15, characterized in that, The first part is an optical encoder; Arranging the material to be imprinted on the surface of the optical encoder; The set shapes of the imprint template are periodically arranged along the extension direction of the surface of the optical encoder; The second part is a grating ruler, and the material to be imprinted forms the grating ruler on the surface of the optical encoder after demolding. The manufacturing method according to claim 24 is characterized in that the set shape of the imprint template includes a plurality of first areas and a plurality of second areas, the plurality of first areas and the plurality of second areas are arranged at intervals, and along the lateral direction perpendicular to the extension direction of the surface of the optical encoder, the top surface of the projected shape of the plurality of first areas is higher than the top surface of the projected shape of the plurality of second areas. The manufacturing method according to claim 25 is characterized in that the surface roughness of the first region is greater than the surface roughness of the second region; or, the surface roughness of the first region is less than the surface roughness of the second region. The manufacturing method according to claim 25 or 26 is characterized in that the grating scale includes a plurality of grating lines corresponding to the plurality of second areas, and a plurality of grating grooves corresponding to the plurality of first areas, the plurality of grating lines are periodically arranged along the extension direction of the surface of the optical encoder, and each of the plurality of grating grooves is arranged at intervals between adjacent grating lines. The manufacturing method according to claim 27 is characterized in that the gate line includes a first surface, and the gate groove includes a second surface; the first surface is a light-blocking area of the optical encoder, and the second surface is a light-transmitting area of the optical encoder, or the first surface is a light-transmitting area of the optical encoder, and the second surface is a light-blocking area of the optical encoder. The manufacturing method according to any one of claims 24 to 28 is characterized in that the surface of the optical encoder includes any one of the upper and lower surfaces of a cuboid or a ring, a spherical surface, or the inner and outer surfaces of a cylinder.