A vector light field generation device and method based on Mach-Zehnder interferometer

Abstract

The present invention relates to the field of optics and vector light field modulation technology, and specifically to a vector light field generation device and method based on a Mach-Zehnder interferometer. The laser beam output by a laser, after laser intensity regulation and laser beam expansion, sequentially passes through a spatial light modulator, a first convex lens, a pinhole filter, a first 1 / 4 wave plate group, and a second convex lens, and then is superimposed and synthesized at a Ronchi grating. A polarization beam splitter prism is used to split the light sequentially passing through the Ronchi grating and reflected by a first reflector. A spiral phase plate, a 1 / 4 wave plate, and a beam splitter prism with opposite topological charges arranged in a subsequent optical path are used to generate a rich variety of vector light fields. The principle is simple and the device is easy to adjust. The major axis orientation and ellipticity of the polarization state of the generated vector light field can be flexibly regulated on the wave surface.

Description

Technical Field

[0001] The present invention relates to the technical field of optics and vector light field modulation, and in particular to a vector light field generating device and method based on a Mach-Zehnder interferometer. Background Art

[0002] Since its birth, lasers have attracted widespread attention from researchers. With the in-depth study of lasers, scientists have tapped its huge potential, and thus the field of light field control has emerged. Light field control involves time domain and space domain control, and the degrees of freedom of control include frequency, phase, amplitude and polarization. Among them, the control of frequency belongs to the control of the time domain, while the control of the phase, polarization and amplitude of the light field is the space domain control of the light field. According to different polarization distributions, light fields can be divided into scalar light fields and vector light fields. Among them, due to the unique polarization distribution of vector light fields, researchers have done a lot of research on them in recent years. It has been proved that vector light fields play an important role in various fields such as quantum optics and quantum information, optical communications, light capture and manipulation, optical imaging, nonlinear optics and astronomy.

[0003] At present, there are many methods to generate vector light fields, including 4f system coherent superposition method, liquid crystal phase plate method and metasurface method. However, in the 4f system coherent superposition experimental device, the types of vector light fields generated by a single one-dimensional grating are limited. If multiple spatial light modulators are used, the flexibility of generating vector light fields will be improved, but the optical path will become more complicated and difficult to adjust, and the quality of the generated light field will also be reduced. Summary of the invention

[0004] The present invention provides a vector light field generating device and method based on Mach-Zehnder interferometer.

[0005] The technical solution of the present invention is as follows:

[0006] A vector light field generating device based on Mach-Zehnder interferometer comprises a laser, a laser intensity regulator, a laser beam expander, a spatial light modulator, a first convex lens, a pinhole filter, a first 1 / 4 wave plate group, a second convex lens, a Ronchi grating, a first reflector, a polarization beam splitter prism, a second reflector group, a spiral phase plate group, a second 1 / 4 wave plate group, a beam splitter prism and an optical camera, characterized in that the laser intensity regulator, the laser beam expander and the spatial light modulator are sequentially arranged along the direction of the laser beam emitted by the laser, the spatial light modulator is located at the front focal plane of the first convex lens, the pinhole filter is placed at the back focal plane of the first convex lens, the first 1 / 4 wave plate group is closely arranged in the direction of the pinhole filter emitting the laser beam, the pinhole filter is located at the front focal plane of the second convex lens, and the Ronchi grating is arranged at the back focal plane of the second convex lens.

[0007] A first reflector and a polarization beam splitter are sequentially arranged in the direction of the outgoing laser beam of the Ronchi grating, a second reflector group, a spiral phase plate group, and a second quarter wave plate group are sequentially arranged in the direction of the outgoing laser beam of the polarization beam splitter, a beam splitter is arranged at the converging point of the two laser beams of the second quarter wave plate group, and an optical camera is arranged in the direction of the outgoing laser beam of the beam splitter.

[0008] The spatial light modulator is loaded with a one-dimensional holographic grating, the optical paths of the two optical paths between the polarization beam splitter prism and the beam splitter prism are equal, and the spiral phase plate group includes two spiral phase plates with opposite topological charges.

[0009] Specifically, the laser intensity regulator includes a half-wave plate and a polarization beam splitter, and the half-wave plate is arranged before the polarization beam splitter.

[0010] Specifically, the first 1 / 4 wave plate group includes two 1 / 4 wave plates with angles of 45° and -45° with the horizontal line, respectively, which are closely attached to the positive first-order aperture and the negative first-order aperture of the aperture filter.

[0011] Specifically, the second quarter wave plate set includes two quarter wave plates, and the angles between the two quarter wave plates and the horizontal line are both 45°.

[0012] A method for generating a vector light field based on a Mach-Zehnder interferometer, comprising:

[0013] S1, the laser emits a laser beam, the light intensity is adjusted by a laser intensity controller, and the beam is expanded by a laser beam expander to obtain a linearly polarized beam with uniform light intensity;

[0014] S2, the linearly polarized light beam passes through the spatial light modulator and is phase modulated by the loaded one-dimensional holographic grating to generate a multi-level diffraction beam;

[0015] S3, the multi-order diffraction beam passes through the first convex lens, and the ±1-order diffraction beam is screened and filtered by a pinhole filter on the rear focal plane, and is modulated by two 1 / 4 wave plates in the first 1 / 4 wave plate group to obtain mutually orthogonal left-right circularly polarized beams;

[0016] S4, the left and right circularly polarized light beams pass through the second convex lens and are superimposed and synthesized at the Ronchi grating. The synthesized light beam is reflected by the first reflector and incident on the polarization beam splitter prism. After the beam is split, the intensity is complementary and the polarization is orthogonal. x , y Linear polarized light;

[0017] S5, two linearly polarized light beams with orthogonal polarizations are incident on two reflectors in the second reflector group respectively, and the two reflected light beams are incident on a spiral phase plate group with opposite topological charges respectively, generating two orthogonal linearly polarized light beams with complementary intensities and opposite spiral phases;

[0018] S6, two beams of light with opposite spiral phases pass through two 1 / 4 wave plates in the second 1 / 4 wave plate group respectively, to obtain left-right circularly polarized beams with complementary intensities and opposite spiral phases;

[0019] S7, two left-right circularly polarized light beams converge to the beam splitter prism and are synthesized into a target light field. The optical camera receives the target light field. The expression of the target light field E is:

[0020] ,

[0021] in, and are the phase factors carrying the spiral phase, m and m are the vortex topological charges carried by the two spiral phase plates, i is an imaginary unit; A is the amplitude of the incident laser; c is the intensity coefficient of the diffracted beam of the spatial light modulator; d is the phase of the diffracted beam loaded on the spatial light modulator; ê r ,ê l are the left-hand and right-hand circular polarization unit vectors respectively; ê x ,ê y They are x , y Linearly polarized unit vector.

[0022] Furthermore, the linearly polarized light beam in S2 passes through a spatial light modulator and is phase modulated by a loaded one-dimensional holographic grating to generate a multi-order diffraction light beam. The transmittance function of the spatial light modulator is:

[0023] ,

[0024] in,( x, y ) is the spatial coordinate of the diffracted light; f 0 is the spatial carrier frequency of the holographic grating; c is the intensity coefficient of the diffracted beam; d is the phase of the diffracted beam;

[0025] Multi-order diffraction beam The expression is:

[0026] ,

[0027] in, A is the amplitude of the incident laser; ( x, y ) is the spatial coordinate of the diffracted light; f 0 is the spatial carrier frequency of the holographic grating; cis the intensity coefficient of the diffracted beam; i is an imaginary unit; d is the phase of the diffracted beam; ê x for x Linearly polarized unit vector.

[0028] Furthermore, the small-aperture filter in S3 filters the ±1st-order diffraction beams, and the ±1st-order diffraction beams E ＋1 、E -1 The expressions are:

[0029] ,

[0030] Among them, E ＋1 is the +1st order diffraction beam, E -1 is the -1st order diffraction beam; A is the amplitude of the incident laser; c is the intensity coefficient of the diffracted beam; e iδ and e -iδ is the phase factor, d is the phase of the diffracted beam, i is an imaginary unit; ê x for x Linearly polarized unit vector.

[0031] After the two 1 / 4 wave plates in the first 1 / 4 wave plate group are modulated, mutually orthogonal left-right circularly polarized beams are obtained. , The expressions are:

[0032] ,

[0033] in, is a left-handed circularly polarized beam, It is a right-handed circularly polarized beam; A is the amplitude of the incident laser; c is the intensity coefficient of the diffracted beam; e iδ and e -iδ is the phase factor, d is the phase of the diffracted beam, i is an imaginary unit; ê r ,ê l are the left-handed and right-handed circular polarization unit vectors respectively.

[0034] Furthermore, the intensity complementarity and polarization orthogonality are obtained in S4. x , y Linearly polarized light, complementary intensities, orthogonal polarizations x, y Linearly polarized beam E 1x 、E 1y The expressions are:

[0035] ,

[0036] Among them, E 1x for x Linearly polarized beam, E 1y for y Linearly polarized beam, A is the amplitude of the incident laser; c is the intensity coefficient of the diffracted beam; d is the phase of the diffracted beam; ê x ,ê y They are x , y Linearly polarized unit vector.

[0037] Furthermore, in S5, two orthogonal linearly polarized light beams with complementary intensities and opposite spiral phases are generated, and two orthogonal linearly polarized light beams E with complementary intensities and opposite spiral phases are generated. 2x 、E 2y The expressions are:

[0038] ,

[0039] Among them, E 2x , E 2y are the opposite spiral phases. x Linearly polarized beam and y Linearly polarized beam, A is the amplitude of the incident laser; c is the intensity coefficient of the diffracted beam; d is the phase of the diffracted beam; and are the phase factors carrying the spiral phase, m and m are the vortex topological charges carried by the two spiral phase plates, i is an imaginary unit; ê x ,ê y They are x , y Linearly polarized unit vector.

[0040] Further, in S6, the left-handed circularly polarized light beams with complementary intensities and opposite spiral phases are obtained, and the left-handed circularly polarized light beams with complementary intensities and opposite spiral phases are obtained. 3l 、E 3r The expressions are:

[0041] ,

[0042] Among them, E 3l , E 3r are left-handed and right-handed circularly polarized beams carrying opposite spiral phases, A is the amplitude of the incident laser; c is the intensity coefficient of the diffracted beam; d is the phase of the diffracted beam; and are the phase factors carrying the spiral phase, m and m are the vortex topological charges carried by the two spiral phase plates, i is an imaginary unit; ê r ,ê l are the unit vectors of left-handed and right-handed circular polarization respectively.

[0043] The beneficial effects of the present invention are:

[0044] The present invention provides a device for generating a vector light field based on a 4f system and a Mach-Zehnder interferometer. The laser beam output by the laser, after laser intensity regulation and laser beam expansion, sequentially passes through a spatial light modulator, a first convex lens, a pinhole filter, a first 1 / 4 wave plate group, and a second convex lens, and is then superimposed and synthesized at a Ronchi grating. A polarization beam splitter prism is used to beam split the light sequentially passing through the Ronchi grating and reflected by a first reflector. A spiral phase plate, a 1 / 4 wave plate, and a beam splitter prism with opposite topological charges are arranged in a subsequent optical path, so that a rich variety of vector light fields are generated. The principle is simple and the device is easy to adjust. The major axis orientation and ellipticity of the polarization state of the generated vector light field can be flexibly regulated on the wave surface.

[0045] 2. The present invention generates a vector light field by converting the spiral phase loaded on the traditional holographic grating into a spiral phase plate. The outstanding feature is that the conversion efficiency is extremely high and there is no restriction on the incident light, which improves the quality of the generated vortex light beam and the efficiency and quality of the vector light field. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In the attached picture:

[0047] Figure 1 Schematic diagram of a vector light field generating device based on Mach-Zehnder interferometer in an embodiment, wherein a is a loaded one-dimensional holographic grating;

[0048] Figure 2 This is an enlarged schematic diagram of the one-dimensional holographic grating loaded in the embodiment;

[0049] Figure 3 In the embodiment n = 1, m = 1, A = 1, c = 1, the four Stokes parameters and polarization states of the vector light field, where n is the diffracted beam phase parameter, m is the vortex topological charge, A is the incident laser amplitude, c is the diffracted beam intensity coefficient;

[0050] Figure 4 are the four Stokes parameters and polarization states of the vector light field when n = 1, m = 2, A = 1, γ = 1 in the embodiment, where: n is the diffracted beam phase parameter, m is the vortex topological charge, A is the incident laser amplitude, c is the diffracted beam intensity coefficient;

[0051] Figure 5 In the embodiment n = 2, m = 1, A = 1, c = 1, the four Stokes parameters and polarization states of the vector light field, where n Diffracted beam phase parameters, m is the vortex topological charge, A is the incident laser amplitude, c is the diffracted beam intensity coefficient;

[0052] The components represented by the reference numerals in the figure are:

[0053] 1. Laser; 2. Laser intensity regulator; 201. Half-wave plate; 202. Polarization beam splitter; 3. Laser beam expander; 4. Spatial light modulator; 5. First convex lens; 6. Pinhole filter; 7. First 1 / 4 wave plate group; 8. Second convex lens; 9. Ronchi grating; 10. First reflector; 11. Polarization beam splitter prism; 12. Second reflector group; 1201. Mirror 1; 1202. Mirror 2; 13. Spiral phase plate group; 1301. Spiral phase plate 1; 1302. Spiral phase plate 2; 14. Second 1 / 4 wave plate group; 1401. 1 / 4 wave plate 1; 1402. 1 / 4 wave plate 2; 15 Beam splitter prism; 16. Optical camera. DETAILED DESCRIPTION

[0054] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings.

[0055] The present invention provides a vector light field generating device based on Mach-Zehnder interferometer, see Figure 1 and Figure 2, comprising a laser 1, a laser intensity regulator 2, a laser beam expander 3, a spatial light modulator 4, a first convex lens 5, a pinhole filter 6, a first 1 / 4 wave plate group 7, a second convex lens 8, a Ronchi grating 9, a first reflector 10, a polarization beam splitter prism 11, a second reflector group 12, a spiral phase plate group 13, a second 1 / 4 wave plate group 14, a beam splitter prism 15 and an optical camera 16, characterized in that, along the direction of the laser beam emitted by the laser 1, the laser intensity regulator 2, the laser beam expander 3 and the spatial light modulator 4 are arranged in sequence, the spatial light modulator 4 is located at the front focal plane of the first convex lens 5, the pinhole filter 6 is placed at the back focal plane of the first convex lens 5, the first 1 / 4 wave plate group 7 is closely arranged on the direction of the pinhole filter 6 emitting the laser beam, the pinhole filter 6 is located at the front focal plane of the second convex lens 8, and the Ronchi grating 9 is arranged at the back focal plane of the second convex lens 8,

[0056] A first reflector 10 and a polarization beam splitter prism 11 are sequentially arranged in the direction of the outgoing laser beam of the Ronchi grating 9, a second reflector group 12, a spiral phase plate group 13, and a second 1 / 4 wave plate group 14 are sequentially arranged in the direction of the outgoing laser beam of the polarization beam splitter prism 11, a beam splitter prism 15 is arranged at the converging point of the two laser beams of the second 1 / 4 wave plate group 14, and an optical camera 16 is arranged in the direction of the outgoing laser beam of the beam splitter prism 15,

[0057] The spatial light modulator 4 is loaded with a one-dimensional holographic grating, the optical paths of the two optical paths from the polarization beam splitter prism 11 to the beam splitter prism 15 are equal, and the spiral phase plate group 13 includes two spiral phase plates with opposite topological charges.

[0058] In the present invention, the laser intensity regulator 2 includes a half-wave plate 201 and a polarization beam splitter 202, which are used to regulate the intensity of the outgoing laser beam generated by the laser 1. The half-wave plate 201 is arranged in front of the polarization beam splitter 202. The outgoing laser beam is incident on the half-wave plate 201, and the half-wave plate 201 deflects the polarization direction of the outgoing light, and then it is incident on the polarization beam splitter 202 and is divided into two beams with mutually perpendicular polarization directions. By rotating the direction of the half-wave plate 201, the polarization beam splitter 202 can only transmit x Linearly polarized light can be used to adjust the intensity of the outgoing laser beam.

[0059] The spatial light modulator 4 is loaded with a one-dimensional holographic grating, and the phase distribution of the diffracted light field is regulated by the grating.

[0060] The first convex lens 5 and the second convex lens 8 are confocal.

[0061] The pinhole filter 6 is arranged at the rear focal plane of the first convex lens 5 and is used to filter the ±1st order diffraction beams.

[0062] The first 1 / 4 wave plate group 7 includes two 1 / 4 wave plates with angles of 45° and -45° to the horizontal line respectively, which are respectively close to the positive first-order pinhole and the negative first-order pinhole of the pinhole filter 6, and are used to convert the two linearly polarized light beams after passing through the pinhole filter 6 into left-right circularly polarized light beams.

[0063] The Ronchi grating 9 is located at the rear focal plane of the second convex lens 8 and is used to synthesize two left-right circularly polarized light beams.

[0064] The polarization beam splitter prism 11 splits the light beam, and the reflected light and the transmitted light after the splitting are y Polarized light and x polarized light.

[0065] The two spiral phase plates in the spiral phase plate group 13 have opposite topological charges, making the two polarizations orthogonal. x , y A linearly polarized beam carries a helical phase.

[0066] The second quarter wave plate group 14 includes two quarter wave plates, each of which has an angle of 45° with the horizontal line, so that two beams of linearly polarized light carrying a spiral phase are converted into two beams of left-handed and right-handed circularly polarized light carrying a spiral phase.

[0067] The beam splitter prism 15 is located at the point where the two outgoing light beams of the second quarter wave plate group 14 converge, and converges the two laser beams into a single piece.

[0068] The optical paths of the two optical paths from the polarization beam splitting prism 11 to the beam splitting prism 15 are equal.

[0069] The optical camera 16 is located after the light is emitted from the beam splitter prism and is used to detect the intensity of the laser.

[0070] The present invention also provides a method for generating a vector light field based on a Mach-Zehnder interferometer, comprising:

[0071] S1, laser 1 emits a laser beam, the light intensity of which is adjusted by laser intensity controller 2, and the light beam is expanded by laser beam expander 3, so as to obtain a linearly polarized beam with uniform light intensity.

[0072] S2. The linearly polarized light beam passes through the spatial light modulator 4 and is phase modulated by the loaded one-dimensional holographic grating to generate a multi-order diffraction light beam.

[0073] Specifically, the transmittance function of the spatial light modulator 4 is:

[0074] ,

[0075] in,( x, y ) is the spatial coordinate of the diffracted light; f 0 is the spatial carrier frequency of the holographic grating; cis the intensity coefficient of the diffracted beam; d is the phase of the diffracted beam;

[0076] After the linearly polarized light beam passes through the spatial light modulator 4, it is phase modulated by the loaded one-dimensional holographic grating to generate a multi-level diffraction light beam. , the expression of multi-order diffraction beam is:

[0077] ,

[0078] in, A is the amplitude of the incident laser; ( x, y ) is the spatial coordinate of the diffracted light; f 0 is the spatial carrier frequency of the holographic grating; c is the intensity coefficient of the diffracted beam; i is an imaginary unit; d is the phase of the diffracted beam; ê x for x Linearly polarized unit vector.

[0079] S3, the multi-order diffraction beam passes through the first convex lens 5, and the ±1-order diffraction beam is screened and filtered by the pinhole filter 6 on its rear focal plane. After being modulated by the two 1 / 4 wave plates in the first 1 / 4 wave plate group 7, mutually orthogonal left-right circularly polarized beams are obtained.

[0080] Specifically, the pinhole filter 6 filters the ±1st order diffraction beams, and the ±1st order diffraction beams E ＋1 、E -1 The expressions are:

[0081] ,

[0082] Among them, E ＋1 is the +1st order diffraction beam, E -1 is the -1st order diffraction beam; A is the amplitude of the incident laser; c is the intensity coefficient of the diffracted beam; e iδ and e -iδ is the phase factor, d is the phase of the diffracted beam, i is an imaginary unit; ê x for x Linear polarization unit vector, i is an imaginary number;

[0083] Furthermore, after the two quarter wave plates in the first quarter wave plate group 7 are modulated, mutually orthogonal left-handed circularly polarized light beams are obtained. , The expressions are:

[0084] ,

[0085] in, is a left-handed circularly polarized beam, It is a right-handed circularly polarized beam; A is the amplitude of the incident laser; c is the intensity coefficient of the diffracted beam; e iδ and e -iδ is the phase factor, d is the phase of the diffracted beam, i is an imaginary unit; ê r ,ê l are the left-handed and right-handed circular polarization unit vectors respectively.

[0086] S4, the left and right circularly polarized light beams pass through the second convex lens 8 and are superimposed and synthesized at the Ronchi grating 9. The synthesized light beams are reflected by the first reflector 10 and incident on the polarization beam splitter prism 11. After the beams are split, the light beams with complementary intensities and orthogonal polarizations are obtained. x , y Linear polarized light.

[0087] Among them, the obtained intensity is complementary and the polarization is orthogonal x , y Linearly polarized beam E 1x 、E 1y The expressions are:

[0088] ,

[0089] Among them, E 1x for x Linearly polarized beam, E 1y for y Linearly polarized beam, A is the amplitude of the incident laser; c is the intensity coefficient of the diffracted beam; d is the phase of the diffracted beam; ê x ,ê y They are x , y Linearly polarized unit vector.

[0090] S5. Two linearly polarized light beams with orthogonal polarization are respectively incident on two reflectors in the second reflector group 12. After reflection, the two light beams are respectively incident on the spiral phase plate group 13 with opposite topological charges, thereby generating two orthogonal linearly polarized light beams with complementary intensities and opposite spiral phases.

[0091] S5 generates two orthogonal linear polarized light beams with complementary intensities and opposite spiral phases. 2x 、E 2y The expressions are:

[0092] ,

[0093] Among them, E 2x , E 2y are the opposite spiral phases. x Linearly polarized beam and y Linearly polarized beam, A is the amplitude of the incident laser; c is the intensity coefficient of the diffracted beam; d is the phase of the diffracted beam; and are the phase factors carrying the spiral phase, m and m are the vortex topological charges carried by the two spiral phase plates, i is an imaginary unit; ê x ,ê y They are x , y Linearly polarized unit vector.

[0094] S6. The two light beams carrying opposite spiral phases pass through two 1 / 4 wave plates in the second 1 / 4 wave plate group 14 respectively to obtain left-right circularly polarized light beams with complementary intensities and opposite spiral phases.

[0095] Specifically, the intensity complements the left-handed circularly polarized beams E carrying opposite spiral phases. 3l 、E 3r The expressions are:

[0096] ,

[0097] Among them, E 3l , E 3r are left-handed and right-handed circularly polarized beams carrying opposite spiral phases, A is the amplitude of the incident laser; c is the intensity coefficient of the diffracted beam; d is the phase of the diffracted beam; and are the phase factors carrying the spiral phase, m and m are the vortex topological charges carried by the two spiral phase plates, i is an imaginary unit; ê r ,ê l are the unit vectors of left-handed and right-handed circular polarization respectively.

[0098] S7, the two left-right circularly polarized light beams converge to the beam splitter prism 15, and are synthesized into a target light field. The optical camera 16 receives the target light field. The expression of the target light field E is:

[0099] ,

[0100] in, and are the phase factors carrying the spiral phase, m and m are the vortex topological charges carried by the two spiral phase plates, i is an imaginary unit; A is the amplitude of the incident laser; c is the intensity coefficient of the diffracted beam of the spatial light modulator; d is the phase of the diffracted beam loaded on the spatial light modulator; ê r ,ê l are the left-hand and right-hand circular polarization unit vectors respectively; ê x ,ê y They are x , y Linearly polarized unit vector.

[0101] First embodiment:

[0102] See also Figure 3 , this example is the generation of a vector field under a certain parameter. The first line is the simulation results of the four Stokes parameters of the light field, the second line is the corresponding experimental results, and the corresponding polarization state simulation results are superimposed on the first line of Stokes parameters S0. The experimental results show that the ellipticity of the polarization state of the light field changes along the radial direction on the wave surface, and the long axis orientation of the polarization state of the light field changes along the hand direction on the wave surface. The relevant parameters are set as follows: the phase of the diffracted beam loaded on the spatial light modulator 4 is d , whose value is set to n π r ∕ r m ,in n is the phase parameter of the diffracted beam loaded on the spatial light modulator 4, and its value is set to 1. The angles between the optical axes of the two quarter wave plates in the first quarter wave plate group 7 and the horizontal line are ±45°, respectively. The topological charges of the two spiral phase plates in the spiral phase plate group 13 are -1 and 1, respectively. The angles between the optical axes of the two quarter wave plates in the second quarter wave plate group 14 and the horizontal line are 45°. The incident laser amplitude A = 1, diffraction beam intensity coefficient of spatial light modulator 4 c = 1. The synthesized light field expression is:

[0103] ,

[0104] in, r is the radial coordinate of the light field, r m is the maximum radius of the light field; f is the rotational coordinate of the light field, i is an imaginary unit; ê r ,ê l are the unit vectors of left-handed and right-handed circular polarization respectively; ê x ,ê y They are x , y Linearly polarized unit vector.

[0105] Second embodiment:

[0106] See also Figure 4 , this example is the generation of a vector field under a certain parameter. The first line is the simulation results of the four Stokes parameters of the light field, the second line is the corresponding experimental results, and the corresponding polarization state simulation results are superimposed on the first line of Stokes parameters S0. Compared with Example 1, the long axis orientation of the polarization state of the light field has changed on the wave surface. The relevant parameters are set as follows: the phase of the diffracted beam loaded on the spatial light modulator 4 is d , whose value is set to n π r ∕ r m ,in n is the phase parameter of the diffracted beam loaded on the spatial light modulator 4, and its value is set to 1. The angles between the optical axes of the two quarter wave plates in the first quarter wave plate group 7 and the horizontal line are ±45° respectively. The topological charges of the two spiral phase plates in the spiral phase plate group 13 are -2 and 2 respectively. The angles between the optical axes of the two quarter wave plates in the second quarter wave plate group 14 and the horizontal line are 45°. The incident laser amplitude A = 1, diffraction beam intensity coefficient of spatial light modulator 4 c = 1. The synthesized light field expression is:

[0107] ,

[0108] in, r is the radial coordinate of the light field, r m is the maximum radius of the light field; f is the rotational coordinate of the light field, i is an imaginary unit; ê r ,ê l are the unit vectors of left-handed and right-handed circular polarization respectively; ê x ,ê y They are x , yLinearly polarized unit vector.

[0109] Third embodiment:

[0110] See also Figure 5 , this example is the generation of a vector field under a certain parameter. The first line is the simulation results of the four Stokes parameters of the light field, the second line is the corresponding experimental results, and the corresponding polarization state simulation results are superimposed on the first line of Stokes parameters S0. Compared with Example 1, the long axis orientation and ellipticity of the polarization state of the light field have changed on the wave surface. The relevant parameters are set as follows: the phase of the diffracted beam loaded on the spatial light modulator 4 is d , whose value is set to n π r ∕ r m ,in n is the phase parameter of the diffracted beam loaded on the spatial light modulator 4, and its value is set to 2. The angles between the optical axes of the two quarter wave plates in the first quarter wave plate group 7 and the horizontal line are ±45° respectively. The topological charges of the two spiral phase plates in the spiral phase plate group 13 are -1 and 1 respectively. The angles between the optical axes of the two quarter wave plates in the second quarter wave plate group 14 and the horizontal line are 45°. The incident laser amplitude A = 1, diffraction beam intensity coefficient of spatial light modulator 4 c = 1. The synthesized light field expression is:

[0111] ,

[0112] in, r is the radial coordinate of the light field, r m is the maximum radius of the light field, f is the rotational coordinate of the light field, i is an imaginary unit; ê r ,ê l are the unit vectors of left-handed and right-handed circular polarization respectively; ê x ,ê y They are x , y Linearly polarized unit vector.

[0113] According to the device and method provided by the present invention, a rich variety of vector light fields can be generated with a relatively simple principle. By using a spatial light modulator, by combining a 4f system and a Mach-Zehnder interferometer, both the type and efficiency of generating vector light fields are taken into account. The long-axis orientation and ellipticity of the polarization state of the light field can be flexibly adjusted on the wave surface, thereby generating a rich variety of vector light fields with a relatively simple principle.

[0114] The above description is only a preferred embodiment of the present invention. It should be pointed out that those skilled in the art may make some improvements without departing from the present invention, and these improvements should also be regarded as within the protection scope of the present invention.

Claims

1. A vector light field generating device based on a Mach-Zehnder interferometer, comprising a laser (1), a laser intensity controller (2), a laser beam expander (3), a spatial light modulator (4), a first convex lens (5), a pinhole filter (6), a first 1 / 4 wave plate group (7), a second convex lens (8), a Ronchi grating (9), a first reflector (10), a polarization beam splitter prism (11), a second reflector group (12), a spiral phase plate group (13), a second 1 / 4 wave plate group (14), a beam splitter prism (15) and an optical camera (16), characterized in that: A laser intensity regulator (2), a laser beam expander (3) and a spatial light modulator (4) are arranged in sequence along the direction of the laser beam emitted by the laser (1); the spatial light modulator (4) is located at the front focal plane of the first convex lens (5); a pinhole filter (6) is placed at the rear focal plane of the first convex lens (5); a first quarter wave plate group (7) is arranged closely to the pinhole filter (6) in the direction of the laser beam emitted; the pinhole filter (6) is located at the front focal plane of the second convex lens (8); a Ronchi grating (9) is arranged at the rear focal plane of the second convex lens (8); A first reflecting mirror (10) and a polarizing beam splitter prism (11) are sequentially arranged in the direction of the outgoing laser beam of the Ronchi grating (9); a second reflecting mirror group (12), a spiral phase plate group (13), and a second quarter-wave plate group (14) are sequentially arranged in the direction of the outgoing laser beam of the polarizing beam splitter prism (11); a beam splitter prism (15) is arranged at the converging point of two laser beams of the second quarter-wave plate group (14); and an optical camera (16) is arranged in the direction of the outgoing laser beam of the beam splitter prism (15). The spatial light modulator (4) is loaded with a one-dimensional holographic grating, the optical paths of the two optical paths between the polarization beam splitter prism (11) and the beam splitter prism (15) are equal, and the spiral phase plate group (13) includes two spiral phase plates with opposite topological charges; The laser intensity regulator (2) comprises a half-wave plate (201) and a polarization beam splitter (202), wherein the half-wave plate (201) is arranged in front of the polarization beam splitter (202).

2. The vector light field generating device based on Mach-Zehnder interferometer according to claim 1, characterized in that: The first quarter wave plate group (7) comprises two quarter wave plates with angles of 45° and -45° to the horizontal line respectively, which are respectively closely attached to the positive first-order aperture and the negative first-order aperture of the aperture filter (6).

3. The vector light field generating device based on Mach-Zehnder interferometer according to claim 1, characterized in that: The second quarter wave plate group (14) comprises two quarter wave plates, each of which has an angle of 45° with the horizontal line.

4. A method for generating a vector light field based on a Mach-Zehnder interferometer, applied to the device for generating a vector light field based on a Mach-Zehnder interferometer according to claims 1-3, characterized in that: include: S1, a laser (1) emits a laser beam, the light intensity of which is adjusted by a laser intensity controller (2) and the light beam is expanded by a laser beam expander (3) to obtain a linearly polarized beam with uniform light intensity; S2, the linearly polarized light beam passes through the spatial light modulator (4), and is phase modulated by the loaded one-dimensional holographic grating to generate a multi-order diffraction light beam; S3, the multi-order diffraction beam passes through the first convex lens (5), and the ±1-order diffraction beams are screened and filtered by the pinhole filter (6) on the rear focal plane of the first convex lens, and are modulated by two 1 / 4 wave plates in the first 1 / 4 wave plate group (7) to obtain mutually orthogonal left-right circularly polarized beams; S4, the left and right circularly polarized light beams pass through the second convex lens (8) and are then superimposed and synthesized at the Ronchi grating (9). The synthesized light beams are reflected by the first reflector (10) and incident on the polarization beam splitting prism (11). After the beams are split, the light beams are complementary in intensity and orthogonal in polarization. x , y Linear polarized light; S5, two linearly polarized light beams with orthogonal polarizations are incident on two reflectors in the second reflector group (12) respectively, and the two reflected light beams are incident on the spiral phase plate group (13) with opposite topological charges respectively, thereby generating two orthogonal linearly polarized light beams with complementary intensities and opposite spiral phases; S6, the two light beams carrying opposite spiral phases pass through two quarter wave plates in the second quarter wave plate group (14) respectively, to obtain left-right circularly polarized light beams with complementary intensities and opposite spiral phases; S7, the two left-right circularly polarized light beams converge to the beam splitter prism (15) and are synthesized into a target light field. The optical camera (16) receives the target light field. The expression of the target light field E is: ， in, and are the phase factors carrying the spiral phase, m and m are the vortex topological charges carried by the two spiral phase plates, i is an imaginary unit; A is the amplitude of the incident laser; γ is the intensity coefficient of the diffracted beam of the spatial light modulator; δ is the phase of the diffracted beam loaded on the spatial light modulator; ê l ,ê r are the left-hand and right-hand circular polarization unit vectors respectively; ê x ,ê y They are x , y Linearly polarized unit vector.

5. The method for generating a vector light field based on a Mach-Zehnder interferometer according to claim 4, characterized in that: The linearly polarized light beam in S2 passes through a spatial light modulator (4) and is phase modulated by a loaded one-dimensional holographic grating to generate a multi-order diffraction light beam. The transmittance function of the spatial light modulator (4) is: ， in,( x, y ) is the spatial coordinate of the diffracted light; f 0 is the spatial carrier frequency of the holographic grating; γ is the intensity coefficient of the diffracted beam; δ is the phase of the diffracted beam; Multi-order diffraction beam The expression is: ， in, A is the amplitude of the incident laser; ( x, y ) is the spatial coordinate of the diffracted light; f 0 is the spatial carrier frequency of the holographic grating; γ is the intensity coefficient of the diffracted beam; i is an imaginary unit; δ is the phase of the diffracted beam; ê x for x Linearly polarized unit vector.

6. The method for generating a vector light field based on a Mach-Zehnder interferometer according to claim 4, characterized in that: The small hole filter (6) in S3 filters the ±1st order diffraction beams, and the ±1st order diffraction beams E ＋1 、E -1 The expressions are: ， Among them, E ＋1 is the +1st order diffraction beam, E -1 is the -1st order diffraction beam; A is the amplitude of the incident laser; γ is the intensity coefficient of the diffracted beam; e iδ and e -iδ is the phase factor, δ is the phase of the diffracted beam, i is an imaginary unit; ê x for x Linear polarization unit vector; After the two 1 / 4 wave plates in the first 1 / 4 wave plate group (7) are modulated, mutually orthogonal left-right circularly polarized light beams are obtained. , The expressions are: ， in, is a left-handed circularly polarized beam, It is a right-handed circularly polarized beam; A is the amplitude of the incident laser; γ is the intensity coefficient of the diffracted beam; e iδ and e -iδ is the phase factor, δ is the phase of the diffracted beam, i is an imaginary unit; ê l ,ê r are the left-handed and right-handed circular polarization unit vectors respectively.

7. The method for generating a vector light field based on a Mach-Zehnder interferometer according to claim 4, characterized in that: The intensity complementarity and polarization orthogonality are obtained in S4. x , y Linearly polarized light, complementary intensities, orthogonal polarizations x , y Linearly polarized beam E 1x 、E 1y The expressions are: ， Among them, E 1x for x Linearly polarized beam, E 1y for y Linearly polarized beam, A is the amplitude of the incident laser; γ is the intensity coefficient of the diffracted beam; δ is the phase of the diffracted beam; ê x ,ê y They are x , y Linearly polarized unit vector.

8. The method for generating a vector light field based on a Mach-Zehnder interferometer according to claim 4, characterized in that: In the S5, two orthogonal linear polarized light beams with complementary intensities and opposite spiral phases are generated, and two orthogonal linear polarized light beams E with complementary intensities and opposite spiral phases are generated. 2x 、E 2y The expressions are: ， Among them, E 2x , E 2y are the opposite spiral phases. x Linearly polarized beam and y Linearly polarized beam, A is the amplitude of the incident laser; γ is the intensity coefficient of the diffracted beam; δ is the phase of the diffracted beam; and are the phase factors carrying the spiral phase, m and m are the vortex topological charges carried by the two spiral phase plates, i is an imaginary unit; ê x ,ê y They are x , y Linearly polarized unit vector.

9. The method for generating a vector light field based on a Mach-Zehnder interferometer according to claim 4, characterized in that: In S6, the left-handed circularly polarized light beams with complementary intensities and opposite spiral phases are obtained, and the left-handed circularly polarized light beams with complementary intensities and opposite spiral phases are obtained. 3l 、E 3r The expressions are: ， Among them, E 3l , E 3r are left-handed and right-handed circularly polarized beams carrying opposite spiral phases, A is the amplitude of the incident laser; γ is the intensity coefficient of the diffracted beam; δ is the phase of the diffracted beam; and are the phase factors carrying the spiral phase, m and m are the vortex topological charges carried by the two spiral phase plates, i is an imaginary unit; ê l ,ê r are the unit vectors of left-handed and right-handed circular polarization respectively.

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