CN116300065A - An experimental system for generating surface plasmons - Google Patents

Abstract

The embodiment of the invention provides an experimental system for generating surface plasmons, which is used for completing modulation of an incident light beam through reflection of a spatial light modulator loaded with Oldham light beam spectrum information, and extracting light beam information carried by positive primary interference fringes on a far field through a spatial filter consisting of a first Fourier lens, a diaphragm and a second Fourier lens to obtain an initial light field of the Oldham light beam; the initial light field of the Oldham light beam irradiates on a grating structure of a silver film of a glass substrate, and the light beam is coupled and excited with surface plasmon polariton excitons through the grating, so that surface plasmon polaritons are generated on a silver-air interface; the wave fronts of Gaussian beams are modulated by the spatial light modulator to generate Oldham beams with different parameters, so that surface plasmons with corresponding parameters and characteristics are generated, and the method has the advantages of being low in manufacturing cost, simple in system structure, convenient to experiment and operate and the like, and improves efficiency.

Description

An experimental system for generating surface plasmons

technical field

Embodiments of the present invention relate to the field of optical technology, and in particular to an experimental system for generating surface plasmons.

Background technique

Surface plasmons are surface waves that can highly concentrate energy at the interface between metals and dielectrics. In recent years, with the progress and development of nanoscience, surface plasmons have attracted extensive attention in various research fields. In 2010, inspired by the study of non-diffraction beams, Airy surface plasmons were proposed as a non-diffraction-like plasmon, and then proved experimentally. Several special techniques have been developed for experimental methods of generating surface plasmons, one of which is the grating coupling technique, which uses grating vectors to correct the wave vector mismatch between the free-space beam radiation and the surface plasmon polaritons relationship, thereby generating surface plasmons at the interface between the metal and the dielectric.

In 2015, Belafhal et al. proposed a new class of solutions to the scalar non-diffracting Helmholtz equation: finite Olver beams. This new class of beams has a specific order; among them, the zeroth order of this class of beams was first proposed by Berry et al. in the context of quantum mechanics in 1979 to describe ordinary Airy beams. As a theoretical extension of ordinary finite Airy beams, finite Orpher beams have peculiar propagation characteristics such as self-acceleration and self-focusing.

Surface plasmons can manipulate electromagnetic waves in sub-wavelength structures, and have extensive research significance and application backgrounds in optical sensing, biomarkers, and optoelectronic technology. In addition, the experimental generation system of surface plasmons has potential significance and value for the research of nanoscale plasmonic devices; the surface plasmon generation system in the prior art has complex structure, high cost and complicated operation, and it is used in experiments It is relatively difficult, and the transmission characteristics of the generated surface plasmons are limited, and the characteristic modulation is not easy.

Contents of the invention

An embodiment of the present invention provides an experimental system for generating surface plasmons to solve the problem that the surface plasmon generating system in the prior art has a complex structure, high cost, and complicated operation, and is difficult to apply in experiments.

In order to solve the above technical problems, an embodiment of the present invention provides an experimental system for generating surface plasmons, including a laser, an interference module, and a grating silver film;

The laser is used to emit a Gaussian beam;

The interference module is used to split the Gaussian beam into a first incident beam and a second incident beam, and after loading the spectrum information of the Orfer beam in the first incident beam, the first incident beam and the The second incident light beam is subjected to interference processing, and the beam information carried by the positive first-order interference fringes on the far field is extracted to obtain the initial light field of the Orfer beam;

The grating silver film is used to excite surface plasmons after receiving the initial light field of the Orfer beam.

Preferably, the interference module includes a cubic beam splitting crystal, a spatial light modulator and a spatial filter;

The cubic beam splitting crystal is used to receive the Gaussian beam, divide the Gaussian beam into a first incident beam and a second incident beam, send the first incident beam to the spatial light modulator, and divide the second incident beam into the spatial light modulator. The incident beam is sent to a spatial filter;

The spatial light modulator is used to perform wavefront modulation on the first incident light beam, so as to load the spectrum information of the Orfer beam in the first incident light beam, and reflect the modulated modulated light beam to the cubic beam splitting crystal , and send to the spatial filter through the cubic beam splitting crystal;

The spatial filter is used for interfering the modulated light beam with the first incident light beam, and extracting light beam information carried by positive order interference fringes in the far field to obtain an initial light field of the Orfer light beam.

Preferably, it also includes a beam expansion and collimation system, the beam expansion and collimation system is arranged between the laser and the cubic beam splitting crystal, and the beam expansion and collimation system is used to expand the Gaussian beam emitted by the laser. Beam and collimation adjustments.

Preferably, the spatial light filter includes a first Fourier lens, a stop and a second Fourier lens, and the stop is arranged at the focal plane of the image side of the first Fourier lens;

The first Fourier lens is used to perform Fourier transform modulation on the modulated light beam and the second incident light beam;

The aperture is used to select positive first-order interference fringes of the modulated light beam and the second incident light beam;

The second Fourier lens is used to perform Fourier transform on the first-order interference fringes, and obtain the initial light field of the Orfer beam at the focal plane of the image side.

Preferably, the grating silver film is arranged at the focal plane of the image side of the second Fourier lens;

The grating silver film includes a glass substrate, and a metal silver film in a grating structure arranged on the glass substrate.

Preferably, the grating structure is arranged longitudinally periodically, and the longitudinal period of the grating structure is equal to the wavelength of the positive first-order interference fringe for a long time.

Preferably, the spectrum information of the Orfer beam is a phase hologram, and the phase hologram is obtained by interfering the initial light field of the Orfer beam with a simulated plane wave.

Preferably, it also includes a computer, the computer is connected to the spatial light modulator, and the computer is used to adjust different parameters to obtain different initial light fields of the Orfer beam, so as to obtain different forms of surface plasmons , and transmit the phase hologram to the spatial light modulator.

Preferably, a scanning near-field optical microscope is also included, and the scanning near-field optical microscope is used to observe surface plasmons within the transmission distance range.

An experimental system for generating surface plasmons provided by an embodiment of the present invention completes the modulation of the incident beam through the reflection of the spatial light modulator loaded with the spectral information of the Orfer beam, and then passes through the first Fourier lens The spatial filter composed of , diaphragm and the second Fourier lens extracts the beam information carried by the positive first-order interference fringes on the far field to obtain the initial light field of the Orfer beam; the initial light field of the Orfer beam is irradiated On the grating structure of the silver film on the glass substrate, the light beam is coupled and excited by the grating and the surface plasmon polaritons, thereby generating surface plasmon polaritons on the silver-air interface. Modulating to generate Orfer beams with different parameters, and then generating surface plasmons with corresponding parameters and characteristics, has the advantages of low cost, simple system structure, convenient experimental operation, etc., and improves efficiency.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

1 is a schematic structural diagram of an experimental system for generating surface plasmons according to an embodiment of the present invention;

2 is an initial light field diagram of an Orfer beam according to an embodiment of the present invention, wherein (a) and (b) respectively correspond to odd and even orders of the beam order;

Fig. 3 is a silver film structure diagram with a grating structure according to an embodiment of the present invention;

Fig. 4 is a schematic diagram of surface plasmon propagation according to an embodiment of the present invention; wherein, (a) and (b) respectively correspond to the odd order and the even order of the beam order;

FIG. 5 is a simulation diagram of propagation of surface plasmons at the interface between a metal silver film and air according to an embodiment of the present invention; wherein, (a), (b), (c), and (d) correspond to light beams, respectively. Order n=0, 1, 2, 3;

Fig. 6 is an interference diagram of a simulated surface plasmon at the interface between a metal silver film and air according to an embodiment of the present invention; wherein, (a) corresponds to two surface plasmons with beam order n=0 , (b) corresponds to the interference of two surface plasmons of beam order n=0 and n=1, (c) corresponds to the interference of two surface plasmons of beam order n=1.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

The term "and/or" in the embodiment of the present application is only an association relationship describing associated objects, which means that there may be three relationships, for example, A and/or B, which can mean: A exists alone, and A and B exist at the same time , there are three cases of B alone.

The terms "first" and "second" in the embodiments of the present application are used for description purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly indicating the quantity of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present application, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a system, product or equipment comprising a series of components or units is not limited to the listed components or units, but optionally also includes components or units not listed, or optionally also includes the components or units for these products or Other parts or units inherent in equipment. In the description of the present application, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

Reference herein to an "embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The occurrences of this phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is understood explicitly and implicitly by those skilled in the art that the embodiments described herein can be combined with other embodiments.

Surface plasmons can manipulate electromagnetic waves in sub-wavelength structures, and have extensive research significance and application backgrounds in optical sensing, biomarkers, and optoelectronic technology. In addition, the experimental generation system of surface plasmons has potential significance and value for the research of nanoscale plasmonic devices; the surface plasmon generation system in the prior art has complex structure, high cost and complicated operation, and it is used in experiments more difficult.

Therefore, an embodiment of the present invention provides an experimental system for generating surface plasmons, which uses a spatial light modulator to modulate the wavefront of a Gaussian beam to generate Orfer beams with different parameters, and then generates a surface with corresponding parameters and characteristics. Plasmons have the advantages of low cost, simple system structure, and convenient experimental operation, which improves efficiency. An experimental system for generating surface plasmons according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

Fig. 1 provides an experimental system for generating surface plasmons according to an embodiment of the present invention, including a laser, an interference module and a silver grating film;

The laser is used to emit a Gaussian beam; it also includes a beam expansion collimation system, the beam expansion collimation system is arranged between the laser and the cubic beam splitting crystal, and the beam expansion collimation system is used for the laser to emit The output Gaussian beam is expanded and collimated to make the light intensity evenly distributed.

The interference module is used to split the Gaussian beam into a first incident beam and a second incident beam, and after loading the spectrum information of the Orfer beam in the first incident beam, the first incident beam and the The second incident light beam is subjected to interference processing, and the beam information carried by the positive first-order interference fringes on the far field is extracted to obtain the initial light field of the Orfer beam;

The grating silver film (that is, the silver film with a grating structure in FIG. 1 ) is used to excite surface plasmons after receiving the initial light field of the Orfer beam. The grating silver film is arranged at the focal plane of the image side of the second Fourier lens; the grating silver film includes a glass substrate and a metal silver film in a grating structure arranged on the glass substrate. The grating structure is arranged longitudinally periodically, and the longitudinal period of the grating structure is equal to the wavelength of the positive first-order interference fringe for a long time. The initial light field of the Orfer beam is irradiated on the grating structure of the silver film on the glass substrate, and the beam passes through the grating and is coupled with the surface plasmon polaritons to generate surface plasmons on the silver-air interface. Figure 3 is a grating silver film with a grating structure. The grating structure is arranged in a periodic longitudinal direction to reduce energy dissipation during the coupling process, and the length of the longitudinal period of the grating can be close to the wavelength of the beam to facilitate excitation of surface plasmons. .

Also included is a scanning near-field optical microscope for observing surface plasmons over a range of transmission distances.

On the basis of the above embodiments, as a preferred implementation manner, the interference module includes a cubic beam splitting crystal, a spatial light modulator and a spatial filter;

The cubic beam splitting crystal is used to receive the Gaussian beam, divide the Gaussian beam into a first incident beam and a second incident beam, send the first incident beam to the spatial light modulator, and divide the second incident beam into the spatial light modulator. The incident beam is sent to a spatial filter;

The spatial light modulator is used to perform wavefront modulation on the first incident light beam, so as to load the spectrum information of the Orfer beam in the first incident light beam, and reflect the modulated modulated light beam to the cubic beam splitting crystal , and sent to the spatial filter through the cubic beam-splitting crystal; wherein, the spectrum information of the Orfer beam is a phase hologram, and the phase hologram is the interference between the initial light field of the Orfer beam and the simulated plane wave acquired.

The spatial filter is used for interfering the modulated light beam with the first incident light beam, and extracting light beam information carried by positive order interference fringes in the far field to obtain an initial light field of the Orfer light beam. The spatial light filter comprises a first Fourier lens, a diaphragm and a second Fourier lens, and the diaphragm is arranged at the image square focal plane of the first Fourier lens; the first Fourier lens The Fourier lens is used to perform Fourier transform modulation on the modulated light beam and the second incident light beam; the diaphragm is used to select positive first-order interference fringes of the modulated light beam and the second incident light beam; The second Fourier lens is used to perform Fourier transform on the first-order interference fringes, and obtain the initial light field of the Orfer beam at the focal plane of the image side.

On the basis of the above embodiments, as a preferred implementation, it also includes a computer, the computer is connected to the spatial light modulator, and the computer is used to adjust different parameters to obtain different initial light beams of Orfer beams. field to obtain different morphologies of surface plasmons, and transmit the phase hologram to the spatial light modulator.

Figure 2 shows the initial light field of the Orfer beam. Among them, (a) and (b) respectively correspond to the odd order and the even order of the beam order. By adjusting different parameters in the computer, different initial light fields of the Orfer beam can be obtained, and then different forms of surface plasmons can be obtained.

Fig. 4 is a schematic diagram of surface plasmon propagation. Among them, (a) and (b) respectively correspond to the odd order and the even order of the beam order. As shown in the figure, surface plasmons propagate at the metallic silver film-air interface, exhibiting self-accelerating properties.

FIG. 5 is a simulated propagation diagram of surface plasmons at the interface between the metal silver film and air. Among them, (a), (b), (c), and (d) correspond to beam orders n=0, 1, 2, and 3, respectively. Other parameters are set as: Gaussian beam width w ₀ =0.7 μm, wavelength λ=0.7 μm, attenuation factor a ₀ =0.001, and Gaussian term factor b ₀ =0.00025.

FIG. 6 is an interference diagram of simulated surface plasmons at the interface between the metal silver film and air. Among them, (a) corresponds to the interference of two surface plasmons of beam order n=0, (b) corresponds to the interference of two surface plasmons of beam order n=0 and n=1, (c ) corresponds to the interference of two surface plasmons of beam order n=1. Other parameters are set as: Gaussian beam width w ₀ =0.7 μm, wavelength λ=0.7 μm, attenuation factor a ₀ =0.001, and Gaussian term factor b ₀ =0.00025. As shown, surface plasmons exhibit self-focusing properties.

In summary, the embodiment of the present invention provides an experimental system for generating surface plasmons, which completes the modulation of the incident beam through the reflection of the spatial light modulator loaded with the spectral information of the Orfer beam, and then passes through the first A spatial filter composed of a Fourier lens, an aperture and a second Fourier lens extracts the beam information carried by the positive first-order interference fringes on the far field to obtain the initial light field of the Orfer beam; the Orfer beam The initial light field is irradiated on the grating structure of the silver film on the glass substrate, and the beam is coupled and excited by the grating and the surface plasmon polaritons, thereby generating surface plasmons on the silver-air interface; using a spatial light modulator to The wavefront of the Gaussian beam is modulated to generate Orfer beams with different parameters, and then generate surface plasmons with corresponding parameters and characteristics. It has the advantages of low cost, simple system structure, convenient experimental operation, etc., and improves efficiency.

In the above embodiments, all or part of them may be implemented by software, hardware, firmware or any combination thereof. When implemented using software, it may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on the computer, the processes or functions according to the present application will be generated in whole or in part. The computer can be a general purpose computer, a special purpose computer, a computer network, or other programmable devices. The computer instructions may be stored in or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from a website, computer, server or data center Transmission to another website site, computer, server, or data center by wired (eg, coaxial cable, optical fiber, DSL) or wireless (eg, infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium that can be accessed by a computer, or a data storage device such as a server or a data center integrated with one or more available media. The available media may be magnetic media (eg, floppy disk, hard disk, magnetic tape), optical media (eg, DVD), or semiconductor media (eg, SolidState Disk).

Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments are realized. The processes can be completed by computer programs to instruct related hardware. The programs can be stored in computer-readable storage media. When the programs are executed , may include the processes of the foregoing method embodiments. The aforementioned storage medium includes: ROM or random access memory RAM, magnetic disk or optical disk, and other various media that can store program codes.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (9)

1. An experimental system for generating surface plasmons is characterized by comprising a laser, an interference module and a grating silver film;

the laser is used for emitting Gaussian beams;

the interference module is used for splitting the Gaussian beam into a first incident beam and a second incident beam, carrying out interference processing on the first incident beam and the second incident beam after carrying the Oldham beam spectrum information in the first incident beam, and extracting the beam information carried by the positive primary interference fringe on the far field to obtain an initial light field of the Oldham beam;

the grating silver film is used for exciting surface plasmons after receiving an initial light field of the Oldham light beam.

2. The surface plasmon generating experimental system of claim 1 wherein said interference module comprises a cubic beam splitting crystal, a spatial light modulator and a spatial filter;

the cube beam splitting crystal is used for receiving the Gaussian beam, splitting the Gaussian beam into a first incident beam and a second incident beam, sending the first incident beam to the spatial light modulator, and sending the second incident beam to the spatial filter;

the spatial light modulator is used for carrying out wavefront modulation on the first incident light beam so as to load Oldham light beam spectrum information in the first incident light beam, reflect the modulated light beam to the cubic beam splitting crystal and send the modulated light beam to the spatial filter through the cubic beam splitting crystal;

the spatial filter is used for carrying out interference on the modulated light beam and the first incident light beam, and extracting light beam information carried by a positive first-stage interference fringe on a far field to obtain an initial light field of an Oldham light beam.

3. The experimental system for generating surface plasmons of claim 2, further comprising a beam expanding and collimating system, wherein the beam expanding and collimating system is arranged between the laser and the cubic beam splitting crystal, and the beam expanding and collimating system is used for expanding and collimating a gaussian beam emitted by the laser.

4. The experimental system for generating surface plasmons of claim 2, wherein the spatial optical filter comprises a first fourier lens, a stop, and a second fourier lens, the stop being disposed at an image side focal plane of the first fourier lens;

the first Fourier lens is used for carrying out Fourier transform modulation on the modulated light beam and the second incident light beam;

the diaphragm is used for selecting positive first-order interference fringes of the modulated light beam and the second incident light beam;

the second Fourier lens is used for carrying out Fourier transformation on the first-order interference fringes, and an initial light field of the Oldham light beam is obtained at an image space focal plane.

5. The experimental system for generating surface plasmons of claim 4, wherein the grating silver film is disposed at an image side focal plane of the second fourier lens;

the grating silver film comprises a glass substrate and a metal silver film which is arranged on the glass substrate and forms a grating structure.

6. The surface plasmon generating experimental system of claim 5 wherein said grating structures are arranged longitudinally in a periodic pattern, the longitudinal period of said grating structures being substantially equal to the wavelength of the positive primary interference fringes.

7. The experimental system for generating surface plasmons according to claim 2, wherein the spectral information of the oldham beam is a phase hologram, and the phase hologram is obtained by interference of an initial optical field of the oldham beam with a simulated plane wave.

8. The experimental system for generating surface plasmons of claim 7, further comprising a computer coupled to the spatial light modulator, the computer configured to adjust different parameters to obtain initial light fields of different oldham beams to obtain surface plasmons of different morphologies, and to transmit phase holograms to the spatial light modulator.

9. The surface plasmon generating experimental system of claim 8 further comprising a scanning near field optical microscope for observing surface plasmons over a transmission distance range.

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