CN119787094A - A compact power-balanced multi-wavelength laser device and a manufacturing method thereof - Google Patents

Abstract

The invention discloses a compact power balance multi-wavelength laser device and a manufacturing method thereof, wherein the device comprises a multi-channel DFB laser array, a plurality of second-level SOAs, a third-level Y-wave combiner and a first-level SOA; the grating of the DFB laser array is a multi-section grating unit with period gradual change in the laser cavity, and equivalent pi phase shift is introduced between each section so as to realize accurate wavelength interval control and stable single-mode output. The device is formed by laminating an n-type InP substrate, a buffer layer, an n-type InAlGaAs lower limiting layer, a multiple quantum well layer, a p-type InGaAsP upper limiting layer, a grating layer, a p-type InP cladding layer, a p-type InGaAsP transition layer and a p-type InGaAs contact layer. The invention realizes the simultaneous output of multi-wavelength laser under a compact structure by adjusting the working currents of the two-stage SOA and the DFB laser, and has the advantages of uniform wavelength interval, balanced power and high single-mode stability.

Description

Compact type power balance multi-wavelength laser device and manufacturing method thereof

Technical Field

The invention belongs to the technical field of lasers, and particularly relates to a compact power balance multi-wavelength laser device and a manufacturing method thereof.

Background

With the rapid advancement of silicon photonics technologies, optical I/O technology has been widely viewed as an important alternative to traditional electrical I/O technology. Due to the limitation of the number of package pins, the traditional electric I/O technology gradually approaches the performance limit, and is difficult to meet the severe requirements of high-speed and high-density interconnection between chips. In contrast, optical I/O technology, by virtue of its significant advantages of high bandwidth, low latency, low power consumption, and high capacity, provides a more desirable solution for next generation communications and computing applications, and in particular, exhibits great application potential in the context of pursuing high-speed data transmission and high-density interconnection.

In the core component of optical I/O technology, a multi-wavelength laser (MWL) plays a vital role. The MWL can provide a plurality of light sources with different wavelengths simultaneously, supports parallel data transmission, and the performance of the MWL directly relates to key performance indexes such as communication speed, capacity, delay, error rate and the like of the whole system. With the continuous rise of optical communication demands, the development of high-performance multi-wavelength laser sources has become a key point for improving the overall performance of optical I/O technology.

In many MWL researches, DFB laser arrays have become a more ideal choice by virtue of their stable modes, simple operation mechanisms, uniform wavelength spacing, etc. However, when a plurality of DFB lasers are operated in parallel, the thermal crosstalk phenomenon is difficult to avoid, which may lead to an increase in the error of the wavelength interval. In order to achieve a stable and uniform wavelength spacing, it is often necessary to fine tune the operating current of each laser, but this operation often causes output power non-uniformity issues, which adversely affect the overall system performance. Although flip chip bonding, nonlinear polarization rotation effects, and optical attenuator arrays have been proposed to address these issues, they either add complexity to the process or are difficult to implement monolithically.

Therefore, how to design a high-efficiency multi-wavelength laser array capable of precisely controlling the wavelength interval and realizing power balance is still a technical problem to be overcome in the field. In view of the current situation, the invention provides a compact power-balanced multi-wavelength laser device and a manufacturing method thereof, so as to provide a new idea for solving the problem.

Disclosure of Invention

Aiming at the problems of the background technology, the invention provides a compact power balance multi-wavelength laser device and a manufacturing method thereof, which are characterized in that a secondary Semiconductor Optical Amplifier (SOA) with little influence on the accuracy of the output wavelength of a DFB laser is introduced to regulate the output multi-wavelength power, the working current of a multi-channel DFB laser is finely adjusted to ensure uniform wavelength interval, the balance of the output power is ensured, the structure is simple, the power consumption is low, and the integration level is high.

The technical scheme is that the compact power balance multi-wavelength laser device comprises a multi-channel DFB laser array, a second-stage SOA, a third-stage Y-wave combiner and a first-stage SOA.

Wherein the multi-channel DFB laser array includes a plurality of individual DFB lasers disposed on a plurality of different waveguides;

The second-level SOA is provided with a plurality of second-level SOAs, corresponds to the multi-channel DFB laser arrays one by one, is respectively arranged at the front ends of the single DFB lasers, is co-located with the corresponding DFB lasers and is combined into a single waveguide through the three-level Y-combiner;

The laser device realizes output with uniform wavelength interval and power balance by adjusting working currents of the two-stage SOA and the multi-channel DFB laser.

Preferably, the grating of the multichannel DFB laser array is divided into a plurality of sections of grating units, and equivalent pi phase shift (pi-EPS) is introduced between each section of grating units for realizing precise wavelength interval control and stabilizing single-mode output.

Preferably, the grating layer of the multichannel DFB laser array adopts a reconstruction equivalent chirp method, and the grating period linear gradual change is formed through holographic exposure and micron-scale photoetching methods.

Preferably, the output wavelengths of the plurality of DFB lasers are equally spaced and varied, and are adjustable as required, controlled by an internal multi-period linearly graded grating unit.

Preferably, the laser device is formed by laminating an n-type InP substrate, an n-type InP buffer layer, an n-type InAlGaAs lower limiting layer, an InAlGaAs multiple quantum well layer, a p-type InGaAsP upper limiting layer, a p-type InGaAsP grating layer, a p-type InP cladding layer, a p-type InGaAsP transition layer and a p-type InGaAs contact layer in sequence from bottom to top.

Preferably, the p-type InGaAsP grating layer is comprised of a laser grating.

Preferably, in the InAlGaAs multiple quantum well layer, inGaAlAs multiple quantum wells are used as gain media to cover the wavelength output range of the laser device.

Preferably, the multi-channel DFB laser array is an 8-channel DFB laser array, which is formed by connecting 8 DFB lasers in parallel, each DFB laser is arranged on one waveguide, 8 waveguides are arranged side by side in space, 8 secondary SOAs are arranged, each secondary SOA only acts on the DFB lasers of the same waveguide, and the influence on the accuracy of the output wavelength of the DFB lasers acting on the secondary SOAs is small.

Preferably, the power of each channel of the 8-channel DFB laser is regulated under the condition of not increasing the wavelength interval error by regulating the currents of the 8 second-level SOAs, the wavelength interval is uniform by fine-tuning the working current of the 8-channel DFB laser, and the output power is balanced by regulating the working currents of the 8 second-level SOAs.

The technical scheme adopted by the invention also comprises a manufacturing method of the compact power balance multi-wavelength laser, wherein the manufacturing method comprises the following steps of:

Sequentially growing an n-type InP buffer layer, an n-type InAlGaAs lower limiting layer, an InAlGaAs multi-quantum well layer, a p-type InGaAsP upper limiting layer and a p-type InGaAsP grating layer on an n-type InP substrate by a metal organic compound vapor deposition method;

Step two, designing and forming a grating period linear gradual change by adopting a reconstruction equivalent chirp method on the grating layer, and preparing the grating layer by adopting holographic exposure and micron-scale photoetching methods;

And thirdly, sequentially growing a p-type InP cladding layer, a p-type InGaAsP transition layer and a p-type InGaAs contact layer above the grating layer to form a ridge waveguide structure, and coating anti-reflection films at two ends to finish the preparation of the laser.

Compared with the prior art, the technical scheme provided by the invention has the following technical effects:

1. the laser of the invention adopts a linear gradual change grating structure with gradually changing grating period to enhance grating feedback, so that the forbidden bandwidth of the laser is increased, thereby covering the lasing wavelength range of the laser. By introducing phase shift between each segment of grating structure without affecting the gradient of each segment of grating structure, the laser resonant cavity can meet the phase matching condition at the phase shift position to output single-mode laser. And a one-to-one power-on mode of multiple electrodes is adopted, and each phase shift shares one laser resonant cavity, so that each wavelength flattening output is realized.

2. According to the invention, the output multi-wavelength power is regulated by introducing the second-level SOA, and as the influence of the current regulation of the second-level SOA on the wavelength of the series laser is small, the wavelength interval is uniform by fine-tuning the working currents of the plurality of DFB lasers, and the working currents of the plurality of second-level SOAs are regulated to balance the output power without affecting the wavelength accuracy. The invention realizes multi-wavelength coherent planarization output through a single laser, and provides a design of a power balance multi-wavelength source with simple structure, low power consumption and high integration level for the next generation of communication and computing application.

Drawings

FIG. 1 is a schematic diagram of a compact power-balanced multi-wavelength laser device of the present invention;

FIG. 2 is a schematic diagram of a compact power-balanced multi-wavelength laser grating structure according to the present invention;

FIG. 3 is a cross-sectional SEM image of a waveguide of a compact power-balanced multi-wavelength laser apparatus of the present invention;

FIG. 4 is a diagram of a compact power-balanced multi-wavelength laser device according to an embodiment of the present invention;

FIG. 5 is a graph of a linear fit of the test spectra and wavelengths of an 8-channel laser in an embodiment of the invention;

FIG. 6 is a statistical chart of output power and wavelength shift of each channel when the injection current of the second-stage SOA of the 8-channel laser changes from 0mA to 30mA in the embodiment of the invention;

Fig. 7 is a graph showing the single mode characteristic, the output power characteristic and the output power variation of the 8-channel laser when the primary SOA current of the 8-channel laser is changed in the embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the application will be further elaborated in conjunction with the accompanying drawings, and the described embodiments are only a part of the embodiments to which the present invention relates. All non-innovative embodiments in this example by others skilled in the art are intended to be within the scope of the invention. Meanwhile, the step numbers in the embodiments of the present invention are set for convenience of illustration, the order between the steps is not limited, and the execution order of the steps in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

In one embodiment of the invention, a compact power balanced multi-wavelength laser device is structured as shown in fig. 1, and comprises an 8-channel DFB laser array, 8 second-level SOAs, a third-level Y-combiner and 1 first-level SOA.

The 8-channel DFB laser array is formed by connecting 8 single DFB lasers arranged on different waveguides in parallel, each laser is arranged on one waveguide, the 8 waveguides are arranged side by side in space, and the output wavelength of the single DFB laser can be freely designed according to the requirement of practical application.

Further, the grating of the 8-channel DFB laser array is divided into a plurality of sections of grating units, as shown in fig. 2, the period gradient of the grating units in the sections of the grating units realizes the wavelength interval control, equivalent pi phase shift is introduced between each section of grating units to enable adjacent grating units to achieve phase matching, and the existing multi-phase shift structure realizes multi-wavelength lasing output.

In this embodiment, as shown in fig. 3, the compact power-equalizing multi-wavelength laser device is formed by laminating an n-type InP substrate, an n-type InP buffer layer, an n-type inagaas lower confinement layer, an inagaas multi-quantum well layer, a p-type InGaAsP upper confinement layer, a p-type InGaAsP grating layer, a p-type InP cladding layer, a p-type InGaAsP transition layer, and a p-type InGaAs contact layer in this order from bottom to top, wherein the grating layer is formed by a laser grating.

In this embodiment, the phase shift structure between the linear graded grating structure and each segment of grating is implemented by adopting a reconstruction equivalent chirp technology, and equivalent linear graded is implemented by using an equivalent grating structure.

In particular, the laser device of this embodiment introduces a second-stage SOA with less influence on the wavelength shift of the serial laser, adjusts the output multi-wavelength power, makes the wavelength interval uniform by fine-tuning the working current of 8 DFB lasers, and adjusts the working current of 8 second-stage SOAs, so that the output power is balanced and the wavelength accuracy is not affected.

Further, in this embodiment, the manufacturing method of the compact power-equalizing multi-wavelength laser device specifically includes the following steps:

An n-type doped substrate is adopted, and an n-type doped InP buffer layer, an n-type doped limiting layer and an undoped limiting layer are sequentially grown on the substrate through metal organic compound vapor deposition, wherein the related limiting layers are used for limiting an optical field and limiting carriers.

Then, growing InGaAlAs multiple quantum well structure, designing a limiting layer above the quantum well, growing InGaAsP grating layer above the limiting layer, wherein the structure is the related linear gradual change grating period, and the equivalent linear gradual change grating can be designed by adopting a reconstruction equivalent chirp technology, and the equivalent grating period is linearly gradual changed.

And (3) growing p-type InP above the grating layer for burying, growing a waveguide layer related corrosion barrier layer above the contact layer, and then performing waveguide layer growth.

In particular, the present embodiment introduces a plurality of phase shifts in the period of the linear graded grating at equidistant intervals, the bragg grating wavelength variation of the overall laser is set to 6.4 nm, and the wavelength interval between adjacent phase shifts is 0.8nm, so that the first section of grating and the second section of grating share one phase shift, similar to the single phase shift structure described above. By arranging the phase shift structure, the two sections of gratings share one section of phase shift.

Further, the compact type power balance multi-wavelength laser device of the embodiment is shown in fig. 4, and the related test results of the embodiment are shown in fig. 5 to 7.

Fig. 5 (a) is a graph of a test spectrum of an 8-channel laser, and fig. 5 (b) is a graph of a linear fit of test wavelengths, it can be seen that at an operating temperature of 25 ℃, the injection currents of the DFB laser array are respectively 60.5, 54.1, 52.5, 50.2, 49.8, 51.4, 55.7 and 62.3mA, the injection currents of the secondary SOA are respectively 17.5, 18.2, 20.6, 23.2, 25.8, 22.9, 20.3 and 17.3mA, the output wavelengths of the DFB laser array are respectively 1544.47, 1545.32, 1546.11, 1546.87, 1547.64, 1548.41, 1549.20 and 1550.02nm, as can be obtained from the spectral test, the laser can be used for exciting 8 wavelengths in practice, the channel spacing is uniform, the maximum wavelength deviation is only 0.03nm, the side mode rejection ratio (SMSR) is high, the output optical power is flat, and the maximum output power deviation is only 1.01dB.

Fig. 6 (a) shows the variation of the output power of the laser with the injection current of the second-stage SOA during single-channel lasing, and the result shows that the output powers of the channels tend to be consistent by applying different currents to the second-stage SOAs of different channels. Correspondingly, as can be seen from (b) in fig. 6, when the second-stage SOA current is changed within 30mA, the maximum value of the output wavelength shift of 8 channels is only 0.08nm, which further illustrates that the influence of the second-stage SOA on the wavelength shift of the laser is small.

Fig. 7 (a) shows the output power amplifying capability of the primary SOA to the multi-channel laser, and when the primary SOA injection current is 150mA, the output power can reach 20mW. As shown in fig. 7 (b), when the primary SOA current is changed from 50mA to 150mA, the laser can still maintain good single-mode characteristics, the side-mode rejection ratio is above 42dB, and the Standard Deviation (SDOI) of the intensity of the output power of eight channels is lower than 0.6dB, which further shows that the laser device of the present invention has high power output and can maintain the consistency of the output power. Therefore, the designed 8-channel multi-wavelength laser can be judged to be applicable to the related application fields.

In summary, the present invention provides a design scheme of a multi-wavelength source, which adopts a linear graded grating structure to increase the forbidden bandwidth and provide feedback of multiple wavelengths. And introducing phase shift at the equal parts of the integral grating to realize the multiple Bragg wavelength lassification at the phase shift position. The working current of the multichannel DFB laser is finely adjusted to enable the wavelength interval to be uniform, the working currents of the two-level SOAs are adjusted to enable the output power to be balanced, the threshold gain of each wave is low, the threshold current of the whole laser is reduced, the photoelectric conversion efficiency is improved, and meanwhile, the flattened coherent wavelength can be output due to the fact that the same resonant cavity is shared. The invention can realize multi-wavelength output of single laser, with balanced output power, simple structure, low power consumption and high integration level.

The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims (10)

1. The compact power balance multi-wavelength laser device is characterized by comprising a multi-channel DFB laser array, a second-level SOA, a third-level Y combiner and a first-level SOA;

The multi-channel DFB laser array includes a plurality of individual DFB lasers disposed on a plurality of different waveguides;

The two-stage SOA is provided with a plurality of waveguides which are in one-to-one correspondence with the multi-channel DFB laser arrays and are respectively arranged at the front ends of the single DFB lasers, the corresponding DFB lasers are located in the same waveguide, and the plurality of waveguides are combined into a single waveguide through the three-stage Y combiner;

The laser device realizes output with uniform wavelength interval and power balance by adjusting working currents of the two-stage SOA and the multi-channel DFB laser.

2. The compact power balanced multi-wavelength laser device of claim 1, wherein the gratings of the multi-channel DFB laser array are divided into multiple segments of grating elements, a linear graded grating structure is employed, and an equivalent pi phase shift is introduced between each segment of grating elements for wavelength interval control and stable single-mode output.

3. The compact power balanced multi-wavelength laser device of claim 2, wherein the grating layer of the multi-channel DFB laser array is linearly graded in grating period by holographic exposure and micron-scale lithography using a reconstruction equivalent chirp technique.

4. A compact power balanced multi-wavelength laser device as claimed in claim 3 wherein the output wavelengths of the plurality of DFB lasers are equally spaced, controlled as desired by an internal multi-period linear graded grating element.

5. The compact power balanced multi-wavelength laser device of claim 1, wherein the laser device is formed by laminating an n-type InP substrate, an n-type InP buffer layer, an n-type ingagaas lower confinement layer, an ingagaas multiple quantum well layer, a p-type InGaAsP upper confinement layer, a p-type InGaAsP grating layer, a p-type InP cladding layer, a p-type InGaAsP transition layer, and a p-type InGaAs contact layer in this order from bottom to top.

6. The compact power balanced multi-wavelength laser device of claim 5, wherein the p-type InGaAsP grating layer is comprised of a laser grating.

7. The compact power balanced multi-wavelength laser device of claim 5, wherein in the inagaas multi-quantum well layer, a multi-quantum well is an InGaAlAs multi-quantum well as a gain medium covering a wavelength output range of the laser device.

8. The compact power balanced multi-wavelength laser device of claim 1, wherein the multi-channel DFB laser array is an 8-channel DFB laser array formed by connecting 8 DFB lasers in parallel, each DFB laser being disposed on one waveguide, the 8 waveguides being disposed spatially side-by-side, the two-level SOAs being 8, each two-level SOA acting only on DFB lasers on the same waveguide.

9. The compact power balanced multi-wavelength laser device according to claim 8, wherein the power of each channel of the 8-channel DFB laser is adjusted by adjusting the currents of the 8 secondary SOAs in the case of controlling the wavelength interval error, the wavelength interval is made uniform by fine-tuning the operating current of the 8-channel DFB laser, and the output power is equalized by adjusting the operating currents of the 8 secondary SOAs.

10. A method for manufacturing a compact power-equalizing multi-wavelength laser, which is applied to the compact power-equalizing multi-wavelength laser device according to any one of claims 1 to 9, characterized in that the manufacturing method comprises the following steps:

Sequentially growing an n-type InP buffer layer, an n-type InAlGaAs lower limiting layer, an InAlGaAs multi-quantum well layer, a p-type InGaAsP upper limiting layer and a p-type InGaAsP grating layer on an n-type InP substrate by a metal organic compound vapor deposition method;

Step two, designing and forming a grating period linear gradual change by adopting a reconstruction equivalent chirp method on the grating layer, and preparing the grating layer by adopting holographic exposure and micron-scale photoetching methods;

And thirdly, sequentially growing a p-type InP cladding layer, a p-type InGaAsP transition layer and a p-type InGaAs contact layer above the grating layer to form a ridge waveguide structure, and coating anti-reflection films at two ends to finish the preparation of the laser.