CN212391678U - Device for generating vector non-uniform Hermite-associated light beam - Google Patents
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Abstract
The utility model provides a device for generating vector non-uniform Hermite-associated light beams, which comprises a light source, a filter, a beam expander, a reflector, a linear polaroid, a spatial light modulator, a first round hole, a first lens, a second round hole, a second lens, a Gaussian amplitude filter and a radial polarization converter which are arranged in sequence; the expanded light beams are emitted by a reflector, reflected light passes through a linear polarizer and then irradiates a hologram on a spatial light modulator, a first-order diffraction pattern of the hologram is selected by a first round hole, and light emitted from the first round hole sequentially passes through a first lens, a second round hole, a second lens, a Gaussian amplitude filter and a radial polarization converter to obtain vector Hermite non-uniform correlation light beams; this openly can be accurate produce radial polarization Hermite non-uniform correlation light beam, compare in traditional Hermite non-uniform correlation light beam, light intensity scintillation further reduces, and light intensity has obtained further enhancement, can be better be applied to free space optical communication.
Description
Technical Field
The disclosure relates to the field of optical technologies, and in particular to a device for generating vector non-uniform hermitian-correlated light beams.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
High spatial coherence is an important characteristic of laser, and researches find that proper reduction of coherence enables the laser to become partially coherent light, and the laser has better advantages in optical communication and remote sensing technologies. The partial coherent light can be divided into uniformly-correlated (or Sierr-model) partial coherent light and non-uniformly-correlated partial coherent light according to the coherent structure, the non-uniformly-correlated partial coherent light shows self-focusing and self-offset characteristics, and has lower light intensity flicker and higher light intensity in a turbulent medium, and particularly when the laser beam is used for free space optical communication, the characteristic of the non-uniformly-correlated distributed coherent light beam plays a great role. Polarization is a fundamental property of the optical field, and a vector partially coherent light beam can be divided into a uniformly polarized partially coherent light beam and a non-uniformly polarized partially coherent light beam (e.g., a radially polarized partially coherent light beam or an angularly polarized partially coherent light beam) according to the polarization state. The non-uniform polarized light beam can reduce the light intensity flicker in the turbulent flow medium, so the radial polarized Hermite non-uniform associated light beam combining the non-uniform polarization state and the non-uniform associated structure is more beneficial to reducing the light intensity flicker caused by the turbulent flow medium, and plays a great role in optical communication and laser systems.
The inventor of the present disclosure finds that the current researches for generating non-uniform correlation beams are all used for generating scalar non-uniform correlation beams, and cannot accurately generate radial polarization Hermite non-uniform correlation beams with the combination of non-uniform polarization states and non-uniform correlation structures.
Disclosure of Invention
In order to solve prior art's not enough, this disclosure provides a production device of vector inhomogeneous hermitian correlation light beam, the inhomogeneous correlation light beam of Radial Polarization Hermitian (RPHUNC) of production that can be accurate, compares in traditional hermitian inhomogeneous correlation light beam, and light intensity scintillation further reduces, and light intensity has obtained further enhancement, can be better be applied to free space optical communication.
In order to achieve the purpose, the following technical scheme is adopted in the disclosure:
the first aspect of the present disclosure provides a device for generating a vector non-uniform hermitian-correlated beam.
A device for generating vector non-uniform Hermite-associated light beams comprises a reflector, a first branch and a second branch, wherein the first branch and the second branch are arranged on two sides of a reflection point of the reflector;
the first branch comprises a light source, a filter and a beam expander which are sequentially arranged, and an emergent port of the light source and an emergent port of the beam expander are collinear with a reflecting point of the reflector;
the second branch circuit comprises a linear polaroid, a spatial light modulator, a first selection element, a first lens, a second selection element, a second lens, a Gaussian amplitude filter and a radial polarization converter which are sequentially arranged, the center of the linear polaroid, the center of the first lens and the center of the second lens are collinear with a reflection point of the reflector, and the radial polarization converter outputs vector Hermite non-uniform association beams.
Compared with the prior art, the beneficial effect of this disclosure is:
1. compared with the traditional radial polarized light beam (RPPC), the radial polarized Hermite non-uniform correlation light beam (RPHNUC) has unique transmission characteristics, and is particularly characterized in that the RPHNUC can keep hollow distribution and the radial polarization state can be well kept even in a long propagation distance; self-focusing and unique evolution characteristics exist in the medium-distance RPHNUC; the RPHNUC beam has a strong robust structure, and has good application potential in various applications, such as information transmission in free space optical communication, particle capture due to partial coherence and non-uniformity of the RPHNUC beam, polarization sensitive imaging due to spatial structure and polarization of the RPHNUC beam, and the like.
2. The device, through light source, filter, beam expander, speculum, linear polarization piece, spatial light modulator, first round hole, first lens, second round hole, second lens, gauss amplitude filter and the radial polarization converter that sets gradually, the inhomogeneous relevance beam in vector polarization hermitian that produces that can be accurate compares in traditional hermitian inhomogeneous relevance beam in hermitian, further reduction of light intensity scintillation, light intensity has obtained further enhancement, can be better be applied to free space optical communication.
3. The device, utilize the round hole to select the first order diffraction pattern of hologram, the light that comes out from first round hole is through thin lens again after that, then through the second round hole that is used for removing extra light, then rethread collimating lens and gauss amplitude filter obtain final Hermite non-uniform correlation light beam, very big improvement the accuracy of the light beam that generates, the effectual influence of getting rid of disturbing light.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure and are not to limit the disclosure.
Fig. 1 is a schematic structural diagram of a device for generating a vector hermitian non-uniform correlation beam according to embodiment 1 of the present disclosure.
Fig. 2 is an intensity distribution graph of RPHUNC beams of different orders at different transmission distances provided in embodiment 1 of the present disclosure.
Fig. 3 shows RPHNUC beam components S of different orders according to embodiment 1 of the disclosurexAnd SyExperimental results at a certain transmission distance.
1. A helium-neon laser; 2. a filter plate; 3. a beam expander; 4. a mirror; 5. a linear polarizer; 6. a spatial light modulator; 7. a first circular hole; 8. a thin lens; 9. a second circular hole; 10. a collimating lens; 11. a Gaussian amplitude filter; 12. a radial polarization converter; 13. a CCD camera; 14. and (4) a computer.
Detailed Description
The present disclosure is further described with reference to the following drawings and examples.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The embodiments and features of the embodiments in the present disclosure may be combined with each other without conflict.
Example 1:
as shown in fig. 1, an embodiment 1 of the present disclosure provides a device for generating a vector hermitian non-uniform correlated light beam, which includes a he-ne laser 1, a filter (NDF)2, a Beam Expander (BE)3, a Reflector (RM)4, a Linear Polarizer (LP)5, a Spatial Light Modulator (SLM)6, a first circular hole (CA) sequentially arranged according to a light path direction1)7 thin lens (L)1)8, second round hole (CA)2)9, collimating lens (L)2)10, a Gaussian Amplitude Filter (GAF)11 and a Radial Polarization Converter (RPC) 12;
and a CCD camera 13 is arranged on an observation plane at the rear side of the Gaussian amplitude filter and is configured to record the light intensity distribution of Hermite non-uniform correlation light beams in different modes at different positions and different transmission distances.
The Spatial Light Modulator (SLM)6 and the CCD camera 13 are both communicatively connected to a computer (PC).
The production process comprises the following steps: a monochromatic laser beam from a helium-neon laser sequentially passes through a Neutral Density Filter (NDF) and a Beam Expander (BE), then is reflected by a Reflector (RM), then passes through a Linear Polarizer (LP) and then passes through a Spatial Light Modulator (SLM);
the SLM is a phase grating designed by computer holography, then with a Circular Aperture (CA)1) Selecting the first order diffraction pattern of the hologram, followed by a diffraction from CA1The light passes through a thin lens (L)1) Then through a CA for removing extra light1Then passes through a collimating lens (L)2) And a Gaussian Amplitude Filter (GAF) and a Radial Polarization Converter (RPC), wherein a radial polarization Hermite non-uniform correlation beam is generated after the RPC, and then the light intensity distribution of the RPHNUC beam at different positions and different transmission distances can be captured by the CCD.
Since the spots of different diffraction orders after SLM cannot be separated directly, L is used1And L2A 4f imaging system is constructed to obtain a pure first order diffraction spot. The three mosaics in the figure are images of several different patterns of phase grating patterns.
In the spatial frequency domain, the vector partially coherent light beam is characterized by a cross-spectrum matrix,
wherein,
is a matrix element of the cross-spectral density,
respectively, any two position coordinates on the cross section.
According to a non-negative positive definite condition, to be a physically realizable beam, each element of the cross-spectral density matrix may be represented as:
pαβ(v) and
respectively the elements of the following weight matrix and the kernel function of the following form,
weight matrix element pαβ(v) The following inequalities are satisfied:
pxx(v)≥0，pyy(v)≥0，pxx(v)pyy(v)≥|pxy(v)|2 (4)
r (r) is a real scalar function with respect to the coordinate r, pαβ(v)、
And different forms of R (r) correspond to different types of vector partially coherent light of non-uniform correlation structure, when p isαβ(v)，
And R (r) are respectively of the form:
wherein, aαβ(α, β ═ x, y) represents a constant, BαβRepresenting the correlation coefficient;
wherein, w0Representing the initial spot width.
When in free space transmission, according to Fresnel diffraction integral, the cross spectrum density matrix element transmitted to any z plane is as follows:
wherein,
is any two coordinate vectors of the propagation surface, z is the propagation distance, λ is the wavelength of light, k is the wavenumber, and i is the imaginary unit.
Can be combined with
Expressed in the following form:
wherein,
to construct a light source kernel.
Based on the above theoretical basis analysis, in actual practice, discretizing the integral of v in equation (2) for experimental generation of radially non-uniformly correlated beams effectively replaces the continuous distribution of incoherent modes with a finite set, since it has been demonstrated that the pseudo-modal expansion can well approximate the exact integral, even with relatively few moduli. In discrete form, the elements of the cross-spectral density matrix can be represented as:
where N is the mode index, N is the total number of modes, α, β ═ x, y denotes the direction,
Anβand (5) pseudo mode.
Therefore, in any z-plane
The light intensity at a point can be expressed in the form:
n is the number of dummy patterns, sampled over an interval | v ≦ 4a, and with a sampling interval Δ v of 2a/25, i.e. taking 101 patterns, 101 phase maps are synthesized in the computer and loaded into the SLM in a random animation sequence, with the probability p (v) of each dummy pattern occurring being determined by equation (6). The average number of frames per second (fps) of the phase pattern sequence loaded into the SLM is about 15s-1Below the maximum SLM refresh rate of 60 Hz. Then, the intensity of the RPHNUC light beam is obtained by averaging the sequence of pseudo-mode images captured by the CCD, and the number of images used in the experiment is about 1000. The following beam parameters were taken in the experiment, λ 632.8nm, w0＝0.3mm，rc＝0.3mm。
Fig. 2 shows the light intensity distribution of the RPHNUC beams of different orders generated by using the experimental apparatus at different transmission distances, and for comparison, the theoretical results of the same beam parameters are shown in this embodiment. Fig. 2 (a) is a theoretical result, and fig. 2 (b) is an experimental result, where (a/b-0) corresponds to the order m being 0 and (a/b-1) corresponds to the order m being 1.
Different serial numbers represent different beam orders, and 0 (or 1) represents a beam order of m-0 (or m-1). As expected, a small ring of light appears in the middle of the initial ring intensity over a short transmission distance, while the RPHUNC beam maintains the dark hollow beam characteristics in the far field. It can be seen from fig. 2 that our experimental results are consistent with theoretical predictions.
FIG. 3 shows the components S of the RPHNUC beam having different orders at a certain transmission distancexAnd SyThe experimental results of fig. 3 further confirm that the light beam generated by our experiment is an RPHNUC light beam. In fig. 3 (a), m is 0, and z is 0.12m, in fig. 3 (b), m is 1, and z is 0.09 m.
In fact, we can realize the azimuthally polarized Hermite non-uniformly correlated beam by adjusting the voltage of the RPC, and then change the formula (7) into the form of the formula (14):
in conclusion, the experimental generation device for generating the radially (or angularly) polarized Hermite non-uniform correlation partial coherent light beam is designed in the embodiment, the light beam can be quickly and conveniently generated through the experimental generation device, the device is simple in equipment, low in cost, easy to build and high in quality of the generated light beam, and therefore the experimental generation device has a wide application prospect in the fields of industry, scientific research, optical communication and the like.
As will be appreciated by one skilled in the art, embodiments of the present disclosure may be provided as a method, system, or computer program product. Accordingly, the present disclosure may take the form of a hardware embodiment, a software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present disclosure may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, and the like) having computer-usable program code embodied therein.
The present disclosure is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the disclosure. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), or the like.
The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure, and various modifications and changes may be made to the present disclosure by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.
Claims (10)
1. A device for generating vector non-uniform Hermite-associated light beams is characterized by comprising a reflector, a first branch and a second branch, wherein the first branch and the second branch are arranged on two sides of a reflection point of the reflector;
the first branch comprises a light source, a filter and a beam expander which are sequentially arranged, and an emergent port of the light source and an emergent port of the beam expander are collinear with a reflecting point of the reflector;
the second branch circuit comprises a linear polaroid, a spatial light modulator, a first selection element, a first lens, a second selection element, a second lens, a Gaussian amplitude filter and a radial polarization converter which are sequentially arranged, the center of the linear polaroid, the center of the first lens and the center of the second lens are collinear with a reflection point of the reflector, and a light beam enters the second light path through the first branch circuit and the reflection point and then outputs a vector non-uniform Hermite correlation light beam.
2. The apparatus according to claim 1, wherein the first lens and the second lens form a 4f optical system.
3. The apparatus for generating a vector nonuniform hermitian beam according to claim 1, wherein a CCD camera is disposed on a viewing plane behind the Gaussian amplitude filter, and configured to record the light intensity distribution of the hermitian nonuniform correlation beam at different positions and different transmission distances in different modes.
4. The apparatus for generating a vector non-uniform hermitian-correlated beam of light of claim 1 wherein said light source is a helium-neon laser.
5. The apparatus according to claim 1, wherein the expanded beam spot of the beam expander covers a hologram on the spatial light modulator.
6. The apparatus for generating vector non-uniform hermitian beams according to claim 1, wherein said spatial light modulator is connected to a computer terminal.
7. The apparatus according to claim 6, wherein the spatial light modulator is a phase grating designed by computer holography.
8. The apparatus according to claim 1, wherein said first and second selection elements are circular holes.
9. The apparatus for generating a vector non-uniform hermitian-related beam as recited in claim 1, wherein said first lens is a thin lens.
10. The apparatus according to claim 1, wherein the second lens is a collimating lens.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111983816A (en) * | 2020-07-30 | 2020-11-24 | 山东师范大学 | Device and method for generating vector non-uniform Hermite-associated light beam |
| CN112904580A (en) * | 2021-02-05 | 2021-06-04 | 苏州大学 | System and method for generating vector non-uniform correlation light beam |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111983816A (en) * | 2020-07-30 | 2020-11-24 | 山东师范大学 | Device and method for generating vector non-uniform Hermite-associated light beam |
| CN111983816B (en) * | 2020-07-30 | 2023-10-20 | 山东师范大学 | Device and method for generating vector non-uniform hermetia associated light beams |
| CN112904580A (en) * | 2021-02-05 | 2021-06-04 | 苏州大学 | System and method for generating vector non-uniform correlation light beam |
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