Photon orbital angular momentum mode multicore demultiplexing device

Abstract

The application relates to the technical field of optical communication, and particularly discloses a photon orbital angular momentum mode multi-core demultiplexing device which comprises a multi-light-source emitting mechanism, a lens, a vortex generating mechanism, a demultiplexing mechanism and a posture adjusting mechanism; the multiple emitted lights of the multi-light-source emitting mechanism are refracted by the lens and simultaneously enter the vortex generating mechanism; the multiple emitted lights of the vortex generating mechanism enter the demultiplexing mechanism, and the emitted light is vortex light or Gaussian light; the demultiplexing mechanism comprises a phase part, a calibration part and a generating part, the light-receiving surface of the phase part is arranged in the same plane with the light-receiving surface of the calibration part, the phase part is used for demultiplexing the vortex light, the calibration part is used for generating a calibration light source after the Gaussian light passes through, and the generating part is used for determining a vertical error according to the calibration light source; the demultiplexing mechanism is arranged on the posture adjusting mechanism, the posture adjusting mechanism is used for adjusting the light-receiving surface of the calibration part to be perpendicular to the emitted light according to the vertical error, so that the purpose of multi-core simultaneous demultiplexing is achieved.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, and in particular to a photonic orbital angular momentum mode multi-core demultiplexing device. Background Technology

[0002] As modern society's demand for communication capacity increases, people are making greater use of different dimensions of light. Among these efforts, people are paying more and more attention to developing the spatial dimension of light. The emergence of photon orbital angular momentum (OAM) has provided people with a new perspective and direction for expanding communication capacity.

[0003] Space division multiplexing (SDM) technology is involved in existing communications that utilize photon orbital angular momentum. SDM technology refers to the technology of simultaneously transmitting signals through multiple orthogonal channels in space to increase communication capacity. One such technology is called fiber core multiplexing, which uses multi-core optical fibers for signal transmission. This technology can greatly increase communication capacity. However, the difficulty and alignment requirements of simultaneous demodulation of multiple cores are much higher than those of single-core demodulation. Due to the characteristics of multiple cores and multiple light sources, the requirements for simultaneous alignment of multiple light sources are high, which has led to few studies on simultaneous demodulation of multiple cores.

[0004] Therefore, it is of great significance to study a device that can achieve simultaneous demodulation of multiple cores. Summary of the Invention

[0005] The purpose of this invention is to provide a photonic orbital angular momentum mode multi-core demultiplexing device. By adding a calibration unit, a calibration reference is provided for multi-core alignment, and in conjunction with an attitude adjustment mechanism, vertical alignment adjustment of multi-core light is achieved, solving the problem that existing devices are difficult to achieve simultaneous vertical alignment of multi-core light, which leads to difficulties in simultaneous demodulation of multi-core light.

[0006] To address the aforementioned problems, this invention provides a multi-core demultiplexing device for photonic orbital angular momentum modes, comprising a multi-source emission mechanism, a lens, a vortex generation mechanism, a demultiplexing mechanism, and an attitude adjustment mechanism. Multiple emitted beams from the multi-source emission mechanism are simultaneously refracted by the lens and incident onto the vortex generation mechanism. Multiple emitted beams from the vortex generation mechanism are incident onto the demultiplexing mechanism; the emitted beams are vortex beams or Gaussian beams. The demultiplexing mechanism includes a phase section, a calibration section, and a generation section. The light-receiving surface of the phase section is coplanar with the light-receiving surface of the calibration section. The phase section is used to demultiplex the vortex beams. The calibration section is used to generate a calibration light source after the Gaussian beams pass through it. The generation section is used to determine the vertical error based on the calibration light source. The demultiplexing mechanism is mounted on the attitude adjustment mechanism, which adjusts the light-receiving surface of the calibration section to be perpendicular to the emitted beams based on the vertical error.

[0007] In one embodiment, the generation unit includes a generation module and a control module; the calibration unit includes a calibration vortex phase plate and multiple crosses; a portion of the emitted light passes through the crosses to obtain a first light source; and a portion of the emitted light simultaneously passes through the vortex phase plate to obtain a second light source; the generation module is used to obtain a diffraction pattern based on the first light source and a vortex light distribution pattern based on the second light source; the control module is used to control the attitude adjustment mechanism to adjust the demultiplexing mechanism based on the diffraction pattern and the vortex light distribution pattern until the diffraction pattern meets a first preset condition and the vortex light distribution pattern meets a second preset condition.

[0008] In one embodiment, the first preset condition is that the diffraction pattern is characterized by a central bright fringe, which is rectangular and circular from the inside out, with alternating bright and dark stripes around the central bright fringe, and the diffraction pattern exhibits symmetry; the second preset condition is that the ring light intensity of the vortex light in the vortex light distribution pattern is uniformly distributed.

[0009] In one embodiment, the calibration vortex phase plate and the phase section array are arranged together, and a plurality of crosses are arranged on both sides of the calibration vortex phase plate and on both sides of the phase section.

[0010] In one embodiment, the length of the cross is 900–1100 μm, the width of the cross is 900–1100 μm, the radius of the vortex phase plate is 1200–1400 μm, and the order of the vortex phase plate is -3 to +3.

[0011] In one embodiment, the phase section includes multiple transparent media and multiple phase plates; multiple transparent media are arranged along the outgoing light path of the emitted light, with air gaps between adjacent transparent media, and the multiple transparent media are respectively arranged on different attitude adjustment mechanisms; the phase plates and the calibration section are arranged on the light-receiving surfaces of the multiple transparent media, and the phase plates are arranged on the light-emitting surfaces of the multiple transparent media.

[0012] In one embodiment, the thickness of the transparent medium is 5-9 mm, and the thickness of the air gap is 13-17 mm.

[0013] In one embodiment, the lens is disposed between the multi-source emission mechanism and the vortex generating mechanism; the emission end face of the multi-source emission mechanism is coplanar with the object-side focal plane of the lens, and the light-receiving surface of the vortex generating mechanism is disposed on the side away from the image-side focal plane of the lens.

[0014] The most prominent beneficial effects of this invention are as follows:

[0015] Because multiple emitted beams from the multi-source emission mechanism are simultaneously and perpendicularly incident on the vortex phase surface of the vortex generation mechanism, multiple uniform vortex emitted beams can be generated simultaneously when the vortex generation mechanism is loaded with a vortex phase plate. This provides a basis for the simultaneous perpendicular alignment of the vortex beams with the demultiplexing structure. Furthermore, since the demultiplexing mechanism is equipped with a coplanar phase section and a calibration section, when the emitted beam from the vortex generation mechanism without the vortex phase plate is loaded passes through the calibration section, the calibration section generates a calibration light source and generates a corresponding pattern in the generation section to determine the vertical error. Subsequently, the position of the demultiplexing mechanism is adjusted by controlling the attitude adjustment mechanism until the light-receiving surface of the phase section is perpendicular to the multiple emitted beams. When the vortex generation mechanism is loaded with a vortex phase plate, multiple uniform vortex emitted beams are generated and simultaneously and perpendicularly incident on the phase section, realizing the simultaneous demultiplexing (demodulation) of multiple beams of light, thereby achieving the purpose of simultaneous demultiplexing of multi-core light. Attached Figure Description

[0016] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall structure provided by a preferred embodiment of the present invention;

[0018] Figure 2 This is a grayscale image of a seven-core vortex light loaded by a vortex generation mechanism provided in a preferred embodiment of the present invention.

[0019] Figure 3 This is a seven-core vortex light intensity distribution map generated according to a preferred embodiment of the present invention;

[0020] Figure 4 This is a schematic diagram of four phase plates provided in a preferred embodiment of the present invention;

[0021] Figure 5 This is a physical diagram of the demultiplexing mechanism provided in a preferred embodiment of the present invention;

[0022] Figure 6 This is a schematic diagram of the phase section and calibration section on the demultiplexing mechanism provided in a preferred embodiment of the present invention;

[0023] Figure 7 This is a schematic diagram of a cross provided by a preferred embodiment of the present invention;

[0024] Figure 8 This is a schematic diagram of a calibration vortex phase plate provided in a preferred embodiment of the present invention;

[0025] Figure 9This is a diffraction pattern of the intensity distribution of the fundamental mode Gaussian light after passing through the cross of the demultiplexing mechanism, provided by a preferred embodiment of the present invention.

[0026] Figure 10 This is a light intensity distribution diagram of the vortex light after the fundamental mode Gaussian light passes through the calibration vortex phase plate of the demultiplexing mechanism, provided by a preferred embodiment of the present invention.

[0027] Figure 11 This is a light intensity distribution diagram of +1st order vortex light passing through phase plate 1 provided by a preferred embodiment of the present invention;

[0028] Figure 12 This is a light intensity distribution diagram of +1st order vortex light passing through phase plate 2, provided by a preferred embodiment of the present invention;

[0029] Figure 13 This is a light intensity distribution diagram of the +1st order vortex light after being demultiplexed by the demultiplexing mechanism, provided by a preferred embodiment of the present invention.

[0030] Figure 14 This is a light intensity distribution diagram of the -3rd order vortex light after being demultiplexed by the demultiplexing mechanism, provided by a preferred embodiment of the present invention.

[0031] Figure 15 This is a light intensity distribution diagram of +3rd order vortex light after being demultiplexed by a demultiplexing mechanism, provided by a preferred embodiment of the present invention.

[0032] Figure 16 This is a light intensity distribution diagram of the -1 and +1 order superimposed vortex light after being demultiplexed by the demultiplexing mechanism, provided by a preferred embodiment of the present invention.

[0033] The attached figures are labeled as follows:

[0034] 1. Multi-source emission mechanism; 2. Vortex generation mechanism; 3. Demultiplexing mechanism; 30. Phase section; 300. Transparent medium; 301. Phase plate; 31. Calibration section; 310. Calibration vortex phase plate; 311. Cross; 4. Attitude adjustment mechanism; 5. Lens. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0036] In existing technologies, the difficulty and alignment requirements of simultaneous demodulation of multiple cores are much higher than those of single-core demodulation. That is, due to the characteristics of multiple cores and multiple light sources, the requirement for simultaneous vertical alignment of multiple light sources is high, which leads to the problem that it is difficult to achieve simultaneous demodulation of multiple cores.

[0037] To address the aforementioned issues, this solution adds a calibration unit to provide a calibration reference for multi-core alignment and works in conjunction with an attitude adjustment mechanism to achieve vertical alignment adjustment of multi-core light, thus solving the problem that existing devices struggle to achieve simultaneous vertical alignment of multi-core light, leading to difficulties in simultaneous demodulation of multi-core light.

[0038] Please refer to Figures 1 to 16 This application provides a multi-core demultiplexing device for photon orbital angular momentum modes, including a multi-source emission mechanism 1, a vortex generation mechanism 2, a demultiplexing mechanism 3, an attitude adjustment mechanism 4, and a lens 5. Multiple emitted lights from the multi-source emission mechanism 1 are simultaneously and perpendicularly incident on the vortex generation mechanism 2 through refraction by the lens 5. Multiple emitted lights from the vortex generation mechanism 2 are incident on the demultiplexing mechanism 3, and the emitted lights are vortex lights or Gaussian lights. The demultiplexing mechanism 3 includes a phase section 30, a calibration section 31, and a generation section. The light-receiving surface of the phase section 30 and the light-receiving surface of the calibration section 31 are arranged coplanarly. The phase section 30 is used to demultiplex the vortex lights, and the calibration section 31 is used to generate a calibration light source after the Gaussian light passes through it. The generation section is used to determine the vertical error based on the calibration light source. The demultiplexing mechanism 3 is disposed on the attitude adjustment mechanism 4, and the attitude adjustment mechanism 4 is used to adjust the light-receiving surface of the calibration section 31 to be perpendicular to the vortex lights according to the vertical error.

[0039] When the emitted light from the multi-source emission mechanism 1 enters the vortex generation mechanism 2, if the vortex generation mechanism 2 is not loaded with a vortex phase plate, the light generated by the vortex generation mechanism 2 is still Gaussian light, that is, the same as the emitted light characteristics of the multi-source emission mechanism 1. When the vortex generation mechanism 2 is loaded with a phase plate, the light generated by the vortex generation mechanism 2 is vortex light. That is, the multiple emitted lights of the vortex generation mechanism 2 are either vortex light or Gaussian light, depending on whether the vortex generation mechanism 2 is loaded with a vortex phase plate.

[0040] After adopting this setting method, in application, calibration is first performed, that is, multiple light sources are emitted and simultaneously perpendicularly injected into the vortex generating mechanism 2 without the vortex phase plate to generate emitted light. At this time, the emitted light is still Gaussian light. The emitted Gaussian light is injected into the demultiplexing mechanism 3. Since the demultiplexing mechanism 3 includes a calibration unit 31 and a generating unit, the Gaussian light will generate a calibration light source after entering the calibration unit 31. The vertical error in the calibration light source is displayed on the generating unit. The attitude adjustment mechanism 4 adjusts the light receiving surface of the demultiplexing mechanism 3 (i.e. the light receiving surface of the calibration unit 31) to keep it perpendicularly aligned with the multiple emitted light according to the vertical error, so as to meet the alignment requirements of multi-core light. When the vortex generating mechanism 2 is loaded with the vortex phase plate, multiple vortex lights are generated, so that multiple vortex lights can be simultaneously perpendicularly injected into the phase unit 30, and the simultaneous demodulation (demultiplexing) of multiple vortex lights (multi-core light) is completed in the phase unit 30.

[0041] It should be noted that the calibration light source contains information on the perpendicular position of the vortex light and the light-receiving surface of the phase section 30. The generation unit can determine the vertical error by using the information displayed by the calibration light source.

[0042] In some embodiments of this application, regarding the lens 5 described above, such as Figure 1 As shown, in order to achieve simultaneous vertical incidence of multiple beams of light emitted from the multi-source emission mechanism 1 into the vortex generation mechanism 2, a lens 5 is disposed between the multi-source emission mechanism 1 and the vortex generation mechanism 2, and the lens 5 is disposed in the optical path of the multiple beams of light emitted. The emission end face of the multi-source emission mechanism 1 is coplanar with the object-side focal plane of the lens 5, and the light-receiving surface of the vortex generation mechanism 2 is disposed on the side away from the image-side focal plane of the lens 5. That is, the distance between the light-receiving surface of the vortex generation mechanism 2 and the lens 5 is greater than the distance between the lens 5 and the image-side focal plane. With this arrangement, since the end faces of multiple emission light sources are disposed on the object-side focal plane, the emission light sources can simultaneously enter the vortex generation mechanism 2 through the refraction of the lens 5, thereby ensuring that multiple uniform and perfect vortex lights are generated in the vortex generation mechanism 2. It should be noted that, unlike the single-core, the light from the multi-source emission mechanism 1 must simultaneously enter the vortex generation mechanism 2 to ensure the generation of multiple vortex lights.

[0043] Preferably, the multi-source emission mechanism 1 adopts a multi-core single-mode fiber, and more preferably a seven-core single-mode fiber. The emitted light consists of seven fundamental mode Gaussian beams. With this configuration, the seven vortex beams are distributed in a roughly hexagonal shape to match the current arrangement of the seven-core fiber. The intensity distribution of the seven vortex beams is almost the same, and the rings are relatively uniform, making them a relatively perfect vortex beam.

[0044] In some embodiments of this application, regarding the vortex generating mechanism 2 described above, such as Figure 2 and Figure 3 As shown, the vortex generating mechanism 2 preferably loads a vortex phase plate, and the phase diagram of the vortex phase plate loading is as follows. Figure 2 As shown, after light from multiple light sources is emitted to the vortex phase plate, the emitted light can be converted into vortex light, such as... Figure 3 As shown, the intensity distribution of the seven cores is almost identical, and the rings are relatively uniform, making it a near-perfect vortex light.

[0045] The vortex generating mechanism 2 can be loaded with a vortex phase plate as needed. When the vortex generating mechanism 2 is loaded with a vortex phase plate, the emitted light is vortex light; when the vortex generating mechanism 2 is not loaded with a vortex phase plate, the emitted light is Gaussian light.

[0046] Preferably, the phase surfaces of the vortex generating mechanism 2 are arranged in a uniform annular array as follows: Figure 2As shown, multiple phase surfaces are arranged corresponding to the emitted light of the multi-source emission mechanism 1. The position and size of each core on the grayscale image loaded by the multiple phase surfaces are adjustable and can be determined in advance by the position of the multi-core fundamental mode Gaussian light.

[0047] It should be noted that vortex light refers to light carrying the orbital angular momentum of photons. In mathematical expression, it has an additional phase term EXP(imθ) compared to plane waves, where m is called the topological charge (also known as the order) of the vortex light. Since vortex lights of different orders are orthogonal to each other in space, any beam of light in space can be represented by a combination of these vortex lights. In particular, a plane wave can be converted into vortex light by using a vortex phase plate.

[0048] In some embodiments of this application, regarding the demultiplexing mechanism 3 described above, such as Figures 4 to 6 As shown, the demultiplexing mechanism 3 includes a phase section 30, a calibration section 31, and a generation section. The phase section 30 is used to demultiplex the vortex light, the calibration section 31 is used to allow the vortex light to pass through the generation calibration light source, and the generation section is used to determine the vertical error based on the calibration light source. After adopting this setting method, the attitude adjustment mechanism 4 can be controlled by the vertical error situation to make the light-receiving surface of the phase section 30 perpendicular to the vortex light.

[0049] For phase part 30, such as Figure 5 and Figure 6 As shown, the phase section 30 includes two transparent media 300 and four phase plates 301. The two transparent media 300 are arranged sequentially along the outgoing light path of the vortex light, with air gaps between adjacent transparent media 300. The two transparent media 300 are respectively mounted on two attitude adjustment mechanisms 4. Each of the two transparent media 300 has a phase plate 301 and a calibration section 31 on its light-receiving surface, and a phase plate 301 on its light-exiting surface. With this arrangement, the incident vortex light first passes through the phase plate 301 on the front (light-receiving surface) of the first transparent media 300, and undergoes the first phase transition. Phase modulation occurs, and then the light continues to propagate in the transparent medium 300. Upon reaching the phase plate 301 on the back side (light-emitting surface) of the first transparent medium 300, it is subjected to a second phase modulation. Then, it propagates in the air gap and reaches the phase plate 301 on the front side (light-receiving surface) of the second transparent medium 300, where it is subjected to a third phase modulation. After that, it propagates in the transparent medium 300 and reaches the phase plate 301 on the back side (light-emitting surface) of the second transparent medium 300, where it is subjected to a fourth phase modulation. After exiting the transparent medium 300 at a distance away from the vortex generating mechanism 2, demultiplexing is completed within a certain distance.

[0050] The first transparent medium 300 refers to the transparent medium 300 on the side closer to the vortex generating mechanism 2, and the second transparent medium 300 refers to the transparent medium 300 on the side farther away from the vortex generating mechanism 2; both the light-receiving surface and the light-emitting surface of the transparent medium 300 are provided with phase plates 301, i.e. Figure 1 The front side of the transparent medium 300 shown (near) Figure 1 Left side) and back (near) Figure 1 Phase plates 301 are provided on both sides.

[0051] With this setup, each transparent medium 300 can be independently controlled by the attitude adjustment mechanism 4. Recalibration by the calibration unit ensures that the vortex light is perpendicular to the light-receiving surface of the phase unit 30 before entering each transparent medium 300. For example, before the vortex light enters the first transparent medium 300, the attitude adjustment mechanism 4 adjusts the light-receiving surface of the first transparent medium 300 to be perpendicular to the vortex light based on the perpendicular error results generated by the calibration unit 31 and the generation unit on the first transparent medium 300. After two modulations in the first transparent medium 300, the vortex light after two modulations is controlled to be perpendicular to the light-receiving surface of the second transparent medium 300 based on the perpendicular error results generated by the calibration unit 31 and the generation unit on the second transparent medium 300. Since the direction of the vortex light changes after two modulations, this setup ensures that the vortex light is perpendicular to the transparent medium 300 before each modulation, fully meeting the alignment requirements for demultiplexing the vortex light perpendicularly incident on the phase unit 30.

[0052] It should be noted that the number of transparent media 300 in this embodiment is preferably two, but as long as the set number can meet the requirements of vortex optical demultiplexing, the number of transparent media 300 and the corresponding phase plate 301 can be set according to the requirements.

[0053] Furthermore, in order to improve the control accuracy of demultiplexing, such as Figure 5As shown, in this embodiment, the transparent medium 300 is preferably 7mm thick. The material of the transparent medium 300 is preferably quartz (quartz is a mineral composed of silicon dioxide, with the chemical formula SiO2. Pure quartz is colorless and transparent, but it exhibits various colors due to the presence of trace pigment ions or finely dispersed inclusions, or the presence of color centers, which reduces its transparency. It has a vitreous luster and a greasy luster on its fracture surface. It has a hardness of 7, no cleavage, a conchoidal fracture, a specific gravity of 2.65, and is piezoelectric). The thickness of the air gap is preferably 15mm. The thickness of the air gap refers to the distance between the two transparent media 300. In application, after the vortex light undergoes the first phase modulation, it propagates 7mm in the quartz medium, followed by the second phase modulation and propagation 15mm in the air medium, then the third phase modulation and propagation 7mm in the quartz medium, and then the fourth phase modulation. When emitted into the air medium, it is demultiplexed at a distance of 15mm from the back of the transparent medium 300 on the side away from the vortex generating mechanism 2.

[0054] Furthermore, to improve the demultiplexing effect, the phase planes of the four phase plates 301 are different, that is, the phase planes of each of the four phase plates 301 are different, such as... Figure 4 As shown, Figure 4 The one on the left is located on the front of the first transparent medium 300. Figure 4 The second one from the left is located on the back of the first transparent medium 300. Figure 4 The second one from the right is located on the front of the second transparent medium 300. Figure 4 The one on the right is located on the back of the second transparent medium 300.

[0055] It should be noted that the phase plate 301 is set on the transparent medium 300 through multi-plane conversion technology. Multi-plane conversion technology refers to a technology that can transform light into the desired light field mode by passing through multiple spatially separated phase planes. Since this technology can theoretically achieve arbitrary unitary changes, it is widely used in the generation and shaping of special light fields.

[0056] For calibration unit 31, such as Figures 7 to 8As shown, the calibration unit 31 includes a calibration vortex phase plate 310 and multiple crosses 311. The calibration vortex phase plate 310 and the multiple crosses 311 are all disposed on the transparent medium 300 of the phase unit 30. The calibration vortex phase plate 310 and the multiple crosses 311 are all arranged coplanarly with the light-receiving surface of the transparent medium 300. With this arrangement, the attitude adjustment mechanism 4 adjusts the positions of the different transparent media 300 of the phase unit 30, so that the vortex light energy simultaneously passes through the crosses 311. 11 and vortex phase plate 301, after part of the vortex light passes through cross 311, a first light source is obtained; and after part of the vortex light passes through vortex phase plate 301, a second light source is obtained. Since the calibration part 31 is provided on the phase part 30, and the light-receiving surface of the calibration part 31 and the light-receiving surface of the phase part 30 are coplanar, the vertical position relationship between the light-receiving surface of the calibration part 31 and the vortex light is the vertical position between the light-receiving surface of the phase part 30 and the vortex light. The vertical error of the first light source and the second light source is determined in the generation part.

[0057] Each cross 311 has an overall size of 1000*1000μm, with the length of the cross 311 preferably being 1000μm and the width preferably being 1000μm. Figure 7 The cross 311 shown is composed of many rectangles, including two types of rectangles: one is 12 short rectangles with a size of 10μm*100μm, and the other is 2 long rectangles with a size of 10μm*1000μm for each rectangle; the overall size of the vortex phase plate 301 is 1300*1300μm, the radius of the vortex phase plate 301 is preferably 1200μm, and the order of the vortex phase plate is -3 to +3, preferably l=+3.

[0058] For the generation unit, the generation unit includes a generation module and a control module. The generation module is used to obtain a diffraction pattern based on the first light source and a vortex light distribution pattern based on the second light source. The control module is used to control the corresponding attitude adjustment mechanism 4 to adjust the position of the transparent medium 300 of the corresponding phase part 30 based on the diffraction pattern and the vortex light distribution pattern until the diffraction pattern meets the first preset condition and the vortex light distribution pattern meets the second preset condition. When the first and second preset conditions are not met during application, the attitude adjustment mechanism 4 adjusts the position of the transparent medium 300 in six dimensions (up / down, left / right, front / back, tilt, pitch, and rotation) until the first and second preset conditions are met. At this time, the phase plate 301 (the light-receiving surface of the transparent medium 300) is perpendicular to the vortex light. While keeping the transparent medium 300 perpendicular to the vortex light, the attitude adjustment mechanism 4 controls the phase part 30 of the transparent medium 300 to align with the vortex light.

[0059] It should be noted that the generation module can be a light display device, which can represent the pattern of the light source.

[0060] Furthermore, in order to determine the vertical error, the first preset condition is that the diffraction pattern is characterized by a central bright fringe, which is rectangular and circular from the inside out, and a series of alternating bright and dark fringes appear around the central bright fringe. The spacing and width of the fringes depend on the size and wavelength of the cross, and the diffraction pattern is symmetrical. The second preset condition is that the ring light intensity of the vortex light in the vortex light distribution pattern is uniformly distributed.

[0061] With this setup, when the vortex light passes through the cross 311 and the calibrated vortex phase plate 310, a first light source and a second light source are generated. The two light sources form diffraction patterns at the generation point (e.g., ...). Figure 9 (as shown) and vortex light distribution map (as shown) Figure 10 As shown, when the vortex light is not perpendicularly aligned with the light-receiving surface of the phase section 30, the diffraction pattern generated by passing through the cross 311 will not be the pattern of the rectangular aperture diffraction intensity distribution pattern. Furthermore, the vortex light distribution pattern will exhibit uneven ring intensity of other core vortex lights, and the shape will become elliptical. When the rectangular aperture diffraction intensity distribution pattern does not appear simultaneously and the ring intensity of the vortex light distribution pattern is uniformly distributed, the corresponding attitude adjustment mechanism 4 is continuously adjusted to adjust the corresponding phase section 30 so that the light-receiving surface of each phase section 30 can maintain a perpendicular positional relationship with the incident vortex light.

[0062] Furthermore, to improve calibration accuracy, a calibration vortex phase plate 310 is arranged below the phase section 30, and multiple crosses 311 are arranged on both sides of the calibration vortex phase plate 310 and the phase section 30. With this arrangement, before vertical error judgment, the corresponding attitude adjustment mechanism 4 moves the transparent medium 300 vertically upward, so that the vortex light can simultaneously illuminate the vortex phase plate 301 and the crosses 311, thus starting the vertical error judgment. After the vertical error judgment is completed, that is, after the light-receiving surface of the transparent medium 300 is perpendicular to the vortex light, the corresponding attitude adjustment mechanism 4 moves the transparent medium 300 vertically downward until the vortex light can enter the phase plate 301, thereby achieving the purpose of the vortex light perpendicularly incident on the transparent medium 300 and the phase plate 301.

[0063] In some embodiments of this application, regarding the posture adjustment mechanism 4 described above, such as Figure 1 As shown, the attitude adjustment mechanism 4 is preferably a six-dimensional platform, that is, any device that can achieve position adjustment in six dimensions, namely up and down, left and right, forward and backward, tilt, pitch and rotation, can be selected by those skilled in the art according to their actual needs.

[0064] In summary, compared with single-core optical demultiplexing, the multi-core optical demultiplexing scheme of this solution has the following advantages: single-core optical demultiplexing only requires the light to be incident into the demultiplexing device to complete demultiplexing, while in this solution, multi-core optical demultiplexing is used. The phase plate 301 of the phase section 30 has a corresponding structure, and multiple vortex beams must be incident perpendicularly into the corresponding structure to achieve demultiplexing. Therefore, compared with single-core optical demultiplexing, the vertical alignment of the multi-core optical demultiplexing with the phase plate 301 is crucial. This solution is equipped with a calibration section 31, which judges the vertical error by the pattern after the vortex beam passes through the calibration section 31, providing a comparative reference for the vertical alignment of the vortex beam with the light-receiving surface of the phase section 30, thereby achieving better vertical alignment and realizing the purpose of simultaneous demultiplexing (demodulation) of multi-core optical demultiplexing.

[0065] As described above, the basic structure and principle of this scheme are explained. The following section will present the specific demultiplexing process of multi-core optical fibers in this scheme:

[0066] S0, determine the seven core beams of the multi-source emission mechanism 1, and determine the phase surface distribution of the vortex generation structure 2 based on the distribution of the seven core beams;

[0067] S1, the emission end of the multi-source emission mechanism 1 is placed on the object-side focal plane of the lens 5, and the vortex mechanism is placed on the side away from the image-side focal plane of the lens 5, so as to ensure that the emission light of the multi-source emission mechanism 1 is simultaneously and perpendicularly incident on the vortex generating mechanism 2.

[0068] S2, the first transparent medium 300 is moved upward by the attitude adjustment mechanism 4 until the Gaussian light emitted by the vortex generation mechanism 2 penetrates into the cross 311 and the calibration vortex phase plate 310, so that the generation part can obtain the corresponding diffraction pattern and vortex light distribution pattern.

[0069] S3, use the attitude adjustment mechanism 4 to adjust the position of the first transparent medium 300 until the diffraction pattern shows the pattern of the rectangular aperture diffraction intensity distribution pattern and the ring light intensity of the vortex light distribution pattern is uniformly distributed. At this time, the light-receiving surface of the first transparent medium 300 is perpendicular to the emitted light of the vortex generation mechanism 2.

[0070] S4, the first transparent medium 300 is moved down by the attitude adjustment mechanism 4 until the emitted light energy of the vortex generation mechanism 2 is aligned with the preset position of the phase plate 301.

[0071] S5, the second transparent medium 300 is moved upward by the attitude adjustment mechanism 4 until the Gaussian seven-core vortex light emitted by the vortex generation mechanism 2 can penetrate into the cross 311 and the calibration vortex phase plate 310, so that the generation part can obtain the corresponding diffraction pattern. Figure 9 ) and vortex light distribution map ( Figure 10 );

[0072] S6, similar to step S3, until the light-receiving surface of the second transparent medium 300 is perpendicular to the emitted light of the spin generation mechanism 2;

[0073] S7, similar to step S4, until the emitted light of the vortex generating mechanism 2 is aligned with the preset position of the phase plate 301.

[0074] S8, according to the determined phase surface distribution, the vortex phase plate is loaded onto the vortex generating mechanism 2;

[0075] S9, the seven-core vortex beam is demultiplexed after passing through the second transparent medium 300. The demultiplexed +1 order beam spot is as follows: Figure 13 As shown.

[0076] The order of the vortex light is not limited to +1; it can be any order from -3 to +3, or even a superposition of different orders. The intensity distribution diagrams of the demodulated light spots with incident orders of -3 and +3 are shown below. Figure 14 and Figure 15 As shown, the intensity distribution of the demodulated light spot in the superposition of incident orders -1 and 1 is as follows. Figure 16 This invention provides a photonic orbital angular momentum mode multicore demultiplexing device that can demodulate incident multicore vortex light, and is not limited to the order of the vortex light.

[0077] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A photonic orbital angular momentum mode multi-core demultiplexing device, characterized in that, This includes a multi-source emission mechanism, a lens, a vortex generation mechanism, a demultiplexing mechanism, and an attitude adjustment mechanism; Multiple emitted lights from the multi-source emission mechanism are simultaneously refracted by the lens and injected into the vortex generating mechanism. Multiple emitted beams from the vortex generating mechanism are incident on the demultiplexing mechanism, and the emitted beams are vortex beams or Gaussian beams. The demultiplexing mechanism includes a phase section, a calibration section, and a generation section. The light-receiving surface of the phase section and the light-receiving surface of the calibration section are arranged coplanarly. The phase section is used to demultiplex the vortex light. The calibration section is used to generate a calibration light source after the Gaussian light passes through it. The generation section is used to determine the vertical error based on the calibration light source. The demultiplexing mechanism is mounted on the attitude adjustment mechanism, which is used to adjust the light-receiving surface of the calibration section to be perpendicular to the emitted light according to the vertical error.

2. The photonic orbital angular momentum mode multi-core demultiplexing device according to claim 1, characterized in that, The generation unit includes a generation module and a control module; The calibration unit includes a calibration vortex phase plate and multiple crosses; After a portion of the Gaussian light passes through the cross, it becomes the first light source; Furthermore, a portion of the Gaussian light simultaneously passes through the vortex phase plate to obtain a second light source; The generation module is used to obtain a diffraction pattern based on the first light source and a vortex light distribution pattern based on the second light source; The control module is used to control the attitude adjustment mechanism to adjust the demultiplexing mechanism according to the diffraction pattern and the vortex light distribution pattern until the diffraction pattern meets the first preset condition and the vortex light distribution pattern meets the second preset condition.

3. The photonic orbital angular momentum mode multi-core demultiplexing device according to claim 2, characterized in that, The first preset condition is that the diffraction pattern is characterized by a central bright fringe, which is rectangular and circular from the inside out, with alternating bright and dark stripes around the central bright fringe, and the diffraction pattern exhibits symmetry. The second preset condition is that the ring light intensity of the vortex light in the vortex light distribution map is uniformly distributed.

4. The photonic orbital angular momentum mode multi-core demultiplexing device according to claim 2, characterized in that, The calibration vortex phase plate and the phase section array are arranged together, and multiple crosses are arranged on both sides of the calibration vortex phase plate and multiple crosses are arranged on both sides of the phase section.

5. The photonic orbital angular momentum mode multi-core demultiplexing device according to claim 2, characterized in that, The length of the cross is 900–1100 μm, and the width of the cross is 900–1100 μm; The radius of the vortex phase plate is 1200-1400 μm, and the order of the vortex phase plate is -3 to +3.

6. The photonic orbital angular momentum mode multi-core demultiplexing device according to claim 1, characterized in that, The phase section includes multiple transparent media and multiple phase plates; Multiple transparent media are provided along the output light path of the emitted light, with air gaps between adjacent transparent media, and the multiple transparent media are respectively provided on different attitude adjustment mechanisms; The phase plate and the calibration part are provided on the light-receiving surface of the multiple transparent media, and the phase plate is provided on the light-emitting surface of the multiple transparent media.

7. The photonic orbital angular momentum mode multi-core demultiplexing device according to claim 6, characterized in that, The thickness of the transparent medium is 5-9 mm, and the thickness of the air gap is 13-17 mm.

8. The photonic orbital angular momentum mode multi-core demultiplexing device according to claim 1, characterized in that, The lens is disposed between the multi-source emission mechanism and the vortex generation mechanism; The emission end face of the multi-source emission mechanism is coplanar with the object-side focal plane of the lens, and the light-receiving surface of the vortex generation mechanism is located on the side away from the image-side focal plane of the lens.

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