Polarization-independent spatial light obstacle avoidance system and method

Abstract

The invention relates to a polarization-independent spatial light obstacle avoidance system and method, and relates to the technical field of optical communication, and the polarization-independent spatial light obstacle avoidance system comprises a light source; the dual-polarization assembly comprises a light path element and a spatial light modulator, the light path element is used for dividing incident light output by the light source into two polarized light and converting the two polarized light into target polarized light capable of being modulated by the spatial light modulator, and the spatial light modulator is written into at least one complex amplitude of the Airy ring subjected to Fourier transformation so as to modulate the target polarized light; and the lens is used for generating a bottle-shaped light beam for obstacle avoidance based on the target polarized light modulated by the spatial light modulator. According to the invention, signals in any polarization state can be processed, and meanwhile, the bottle-shaped light beam is used for bypassing an obstacle at a specified position, so that the signal transmission efficiency and quality are ensured.

Description

Technical Field

[0001] The present invention relates to the field of optical communication technology, and in particular to a polarization-independent spatial optical obstacle avoidance system and method. Background Art

[0002] As the demand for bandwidth and high data rates in heterogeneous networks continues to grow, spatial optical transmission is widely regarded as the next generation of high-speed wireless communication technology due to its fast, secure and reliable characteristics.

[0003] Currently, the radio frequency band of the electromagnetic spectrum is limited in capacity, and most sub-bands are exclusive and expensive. In contrast, space optical links have a higher available optical bandwidth and can achieve faster communication rates. Space optical communication uses laser as a carrier, which has the characteristics of anti-electromagnetic interference and good confidentiality; the frequency band used is higher than 300GHz, which is an unregulated band worldwide and does not require additional fees; it is easy to deploy and can be reinstalled without the cost of dedicated fiber optic connections. Space optical communications are very attractive in application areas such as MAN (Metropolitan Area Network) extension, LAN (Local Area Network) interconnection, high-definition television and medical image / video transmission, wireless video surveillance, and quantum key distribution.

[0004] A major limitation of space optical communications is susceptibility to beam obstructions, which are often of the same order of magnitude as the beam diameter and can cause power loss or link interruption. Summary of the invention

[0005] The present application provides a polarization-independent spatial light obstacle avoidance system and method, which can process signals in any polarization state and use a bottle-shaped light beam to bypass obstacles at a specified position, thereby ensuring the efficiency and quality of signal transmission.

[0006] In a first aspect, an embodiment of the present application provides a polarization-independent spatial light obstacle avoidance system, the polarization-independent spatial light obstacle avoidance system comprising:

[0007] light source;

[0008] A dual polarization component, comprising an optical path element and a spatial light modulator, wherein the optical path element is used to split the incident light output by the light source into two polarized lights and convert them into target polarized light modulatable by the spatial light modulator, wherein the spatial light modulator is written with the complex amplitude of at least one Airy ring after Fourier transformation to modulate the target polarized light;

[0009] A lens generates a bottle beam for obstacle avoidance based on the target polarized light modulated by the spatial light modulator.

[0010] In combination with the first aspect, in one implementation, the optical path element includes:

[0011] A beam splitter prism, which is used to receive the incident light output by the light source;

[0012] A polarization beam splitter prism, used to split the light beam output by the beam splitter prism into two orthogonal polarized lights;

[0013] A reflector assembly, comprising a first branch and a second branch, wherein the first branch is provided with a first reflector, and the first reflector is used to directly input a polarized light into the spatial light modulator, and the first branch is provided with a second reflector and a half-wave plate, and the second reflector is used to input another polarized light into the half-wave plate for conversion, and then input into the spatial light modulator;

[0014] The reflector assembly is also used to receive the light beam modulated by the spatial light modulator and output it to the lens through the beam splitter prism.

[0015] In combination with the first aspect, in one implementation, the light source is a collimated light source, and the collimated light source includes a laser and a collimator.

[0016] In a second aspect, an embodiment of the present application provides a polarization-independent spatial light obstacle avoidance method, and the polarization-independent spatial light obstacle avoidance method includes:

[0017] The dual polarization component is used to split the incident light output by the light source into two polarized lights, and convert them into target polarized lights that can be modulated by the spatial light modulator;

[0018] Modulating the target polarized light using the spatial light modulator and generating a bottle-shaped beam through a lens;

[0019] The position and size of the bottle body of the bottle beam are adjusted so that the obstacle is located inside the bottle beam and is smaller than the bottle body.

[0020] In conjunction with the second aspect, in one implementation,

[0021] The complex amplitude expression of the Airy ring is: Among them, Ai is the Airy function, r0(θ) is the polar coordinate expression of the ring shape, r is the polar distance, θ is the polar angle, w is the scale factor, and a is the attenuation factor;

[0022] The size of the bottle can be changed by adjusting r0(θ).

[0023] In combination with the first aspect, in one implementation,

[0024] When the bottle body is not circular, the scale factor w is set to So that light beams with different r0(θ) can be focused to the same point, where f is the focusing distance and k is the wave vector.

[0025] In conjunction with the second aspect, in one implementation, a beam splitter grating is used so that the phase written into the spatial light modulator satisfies:

[0026] in, A is the amplitude, is the phase, is the grating phase, and Mod means remainder.

[0027] In conjunction with the second aspect, in one implementation, the method further includes:

[0028] The position of the bottle is changed by adjusting the position of the Fourier-transformed Airy ring light field to adapt to the position of the obstacle.

[0029] In conjunction with the second aspect, in one implementation, the method further includes:

[0030] The angle of the bottle beam can be changed by adjusting the focal length of the lens.

[0031] In combination with the second aspect, in one implementation, the complex amplitudes of a square Airy ring and a circular Airy ring after Fourier transformation are written into the spatial light modulator to achieve space division multiplexing of spatial light.

[0032] The beneficial effects brought by the technical solution provided by the embodiments of the present application include:

[0033] The polarization-independent spatial light obstacle avoidance system of the present application utilizes a dual-polarization component to split the incident light output by a light source into two polarized lights, and converts the light into a target polarized light modulated by a spatial light modulator; utilizes a spatial light modulator having a complex amplitude of at least one Airy ring after Fourier transformation to modulate the target polarized light, and generates a bottle-shaped light beam through a lens; and adjusts the position and size of the bottle body of the bottle-shaped light beam so that the obstacle is located inside the bottle-shaped light beam and is smaller than the bottle body.

[0034] That is, the present application uses a dual polarization component to split the incident light into two polarized lights, and then processes the two components separately, and finally merges them, which can reduce the impact of polarization on system performance. Thus, it can process signals in any polarization state, and use the bottle beam to bypass obstacles at a specified position, ensuring the efficiency and quality of signal transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 This is a structural block diagram of an embodiment of the polarization-independent spatial light obstacle avoidance system of the present application;

[0037] Figure 2 A schematic structural diagram of an embodiment of a dual polarization component of the present application;

[0038] Figure 3 A schematic diagram of the arrangement of two Airy rings for this application;

[0039] Figure 4 This is a schematic diagram of the bottle beam propagation process of this application;

[0040] Figure 5 This is a schematic diagram of bottle-shaped beam focusing in this application;

[0041] Figure 6 This is a schematic diagram of the phase superposition of the bottle beam in this application;

[0042] Figure 7 Schematic diagram of the propagation process of delaying the bottle for this application;

[0043] Figure 8 This is a schematic diagram of the propagation process of the bottle-shaped beam pointing outward at this application angle;

[0044] Fig. 9 This is a flow chart of an embodiment of the polarization-independent spatial light obstacle avoidance method of the present application. DETAILED DESCRIPTION

[0045] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0046] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0047] In a first aspect, an embodiment of the present application provides a polarization-independent spatial light obstacle avoidance system.

[0048] In one embodiment, referring to Figure 1 , Figure 1 This is a structural block diagram of an embodiment of the polarization-independent spatial light obstacle avoidance system of the present application. Figure 1 As shown, the polarization-independent spatial light obstacle avoidance system includes a light source, a dual polarization component and a lens.

[0049] The light source is used to output incident light to the dual polarization component. In the present embodiment, the light source is a collimated light source. Specifically, the collimated light source includes a laser and a collimator. Preferably, the laser is a narrow linewidth external cavity tunable laser. Of course, other types of lasers can also be selected as needed, and this embodiment does not limit this.

[0050] The dual polarization component includes an optical path element and a spatial light modulator, wherein the optical path element is used to split the incident light output by the light source into two polarized lights and convert the light into a target polarized light modulated by the spatial light modulator, wherein the spatial light modulator is written with the complex amplitude of at least one Airy ring after Fourier transformation to modulate the target polarized light. The lens generates a bottle-shaped beam for obstacle avoidance based on the target polarized light modulated by the spatial light modulator.

[0051] For details, see Figure 2 As shown, the optical path elements include a beam splitter prism, a polarization beam splitter prism and a reflector assembly.

[0052] The beam splitter prism is used to receive the incident light output by the light source, and the polarization beam splitter prism is used to split the light beam output by the beam splitter prism into two orthogonal polarized lights.

[0053] The reflector assembly includes a first branch and a second branch. The first branch is provided with a first reflector, which is used to directly input a polarized light into the spatial light modulator. The first branch is provided with a second reflector and a half-wave plate, which is used to input another polarized light into the half-wave plate for conversion and then input into the spatial light modulator. The reflector assembly is also used to receive the light beam modulated by the spatial light modulator and output it to the lens through a beam splitter prism.

[0054] It is worth noting that, generally speaking, a spatial light modulator can only modulate one of the polarization states, namely the target polarization state. For the other polarization state that cannot be modulated, a half-wave plate is required to convert it into a usable polarized light.

[0055] It can be understood that this embodiment uses a polarization beam splitter to split light into two orthogonal polarization components, and then processes the two components separately and finally combines them, which can reduce the impact of polarization on system performance and thus achieve polarization independence.

[0056] The principle of the polarization-independent spatial light obstacle avoidance system is explained below:

[0057] First, the optical path needs to be adjusted. In this embodiment, a light source with a wavelength of 1550nm is taken as an example. Since the 1550nm light source is invisible to the naked eye, when adjusting the dual-polarization optical path, the optical path should be roughly adjusted using visible light, and then the light beam is observed using a CCD (Charge-Coupled Device) to fine-tune the optical path to ensure that the dual-polarization light is incident on the same position on the spatial light modulator and the light beams overlap when emitted from the dual-polarization part.

[0058] The specific operation of fine-tuning is as follows: first load the vortex phase on the spatial light modulator, place the CCD between the first reflector on the left and the spatial light modulator, adjust the optical path so that a standard circular ring can be observed on the CCD, indicating that the polarized light is now located at the center of the loaded phase, and then place the CCD between the second reflector on the right and the spatial light modulator. Repeat the above operation to make the dual polarized light incident on the same position on the spatial light modulator; when adjusting the overlap of the outgoing light beams, the CCD should be placed between the dual polarization component and the lens, and the optical path should be adjusted until only one light spot is observed on the CCD. Since adjusting the optical path will affect the position of the incident light and the outgoing light at the same time, the above operation needs to be performed multiple times. In order to verify the accuracy of the final optical path, a polarization controller can be added in front of the collimated light source to change the polarization state of the laser. If the outgoing light does not change, it means that the system is polarization independent.

[0059] The complex amplitude expression of the Airy ring is: Among them, Ai is the Airy function, r0(θ) is the polar coordinate expression of the ring shape, r is the polar distance, θ is the polar angle, w is the scale factor, and a is the attenuation factor.

[0060] Arrange multiple Airy rings of different shapes in space, perform Fourier transform, write the changed complex amplitude into the spatial light modulator, and the light beam will generate a bottle-shaped beam at the focal plane of the lens after passing through the spatial light modulator. Figure 3 As shown in FIG. 1 , this embodiment takes two Airy rings as an example, where the left side is a square and the right side is a circle. The propagation process is as follows: Figure 4 As shown in the figure, the upper part is a square bottle body, the lower part is a round bottle body, and the dotted line represents the position of the lens. As the propagation distance increases, the bottle body of the bottle-shaped beam will gradually close and finally evolve into a Bessel-like beam, and its focused light field is as follows: Figure 5 When the obstacle is located inside the bottle-shaped beam and is smaller than the bottle, the spatial light can bypass the obstacle without being affected.

[0061] Based on the complex amplitude expression of the Airy ring, we can know that by adjusting r0(θ), we can change the size of the bottle, so as to adapt to obstacles of different sizes. If the bottle is circular, r0(θ) is a constant. When the bottle is of other shapes (non-circular), the scale factor w is set to So that light beams with different r0(θ) can be focused to the same point, where f is the focusing distance and k is the wave vector.

[0062] Since the current spatial light modulator can only modulate the phase or the amplitude, it cannot modulate the amplitude and phase at the same time. When the spatial light modulator used is phase-only, in order to write the amplitude and phase at the same time, the principle of the beam splitter grating is used to make the phase satisfy:

[0063] in, A is the amplitude, is the phase, is the grating phase, and Mod means remainder.

[0064] For the specific phase superposition process, see Figure 6 As shown, the first picture represents the image of M, the second picture represents F, and the third picture represents Additive representation The final multiplication gives the desired phase: Since the phase is in period 2π, and The images are the same image.

[0065] In addition, by applying the angular spectrum theory, the complex amplitude of the light field after the Airy ring light field propagates forward / backward by a distance z is Fourier transformed and written into the spatial light modulator, which can change the position of the bottle to adapt to the position of the obstacle. Figure 7 As shown. Changing the focal length of the lens can change the angle of the bottle beam. Figure 8 As shown, appropriately increasing the focal length of the lens can make the angles of the two bottle-shaped beams point outward.

[0066] It can be understood that the above operations can change the angle of the bottle-shaped light beam, the size and position of the bottle body, so as to better adapt to obstacles and achieve obstacle avoidance.

[0067] In summary, the polarization-independent spatial light obstacle avoidance system in the present application utilizes a dual-polarization component to split the incident light output by a light source into two polarized lights, and converts the light into a target polarized light modulated by a spatial light modulator; utilizes a spatial light modulator having a complex amplitude of at least one Airy ring after Fourier transformation to modulate the target polarized light, and generates a bottle-shaped light beam through a lens; and adjusts the position and size of the bottle body of the bottle-shaped light beam so that the obstacle is located inside the bottle-shaped light beam and is smaller than the bottle body.

[0068] That is, the present application uses a dual polarization component to split the incident light into two polarized lights, and then processes the two components separately, and finally merges them, which can reduce the impact of polarization on system performance. Thus, it can process signals in any polarization state, and use the bottle beam to bypass obstacles at a specified position, ensuring the efficiency and quality of signal transmission.

[0069] In a second aspect, an embodiment of the present application provides a polarization-independent spatial light obstacle avoidance method.

[0070] In one embodiment, referring to Fig. 9 , Fig. 9 This is a flow chart of an embodiment of the polarization-independent spatial light obstacle avoidance method of the present application. Fig. 9 As shown, the polarization-independent spatial light obstacle avoidance method includes:

[0071] S1, using the dual polarization component to split the incident light output by the light source into two polarized lights, and converting them into target polarized lights modulatable by the spatial light modulator;

[0072] S2, modulating the target polarized light using the spatial light modulator, and generating a bottle-shaped beam through a lens;

[0073] S3. Adjust the position and size of the bottle body of the bottle-shaped beam so that the obstacle is located inside the bottle-shaped beam and is smaller than the bottle body.

[0074] Furthermore, in one embodiment,

[0075] The complex amplitude expression of the Airy ring is: Among them, Ai is the Airy function, r0(θ) is the polar coordinate expression of the ring shape, r is the polar distance, θ is the polar angle, w is the scale factor, and a is the attenuation factor;

[0076] The size of the bottle can be changed by adjusting r0(θ).

[0077] Furthermore, in one embodiment,

[0078] When the bottle body is not circular, the scale factor w is set to So that light beams with different r0(θ) can be focused to the same point, where f is the focusing distance and k is the wave vector.

[0079] Furthermore, in one embodiment, a beam splitter grating is used so that the phase written into the spatial light modulator satisfies:

[0080] in, A is the amplitude, is the phase, is the grating phase, and Mod means remainder.

[0081] Furthermore, in one embodiment, it also includes:

[0082] The position of the bottle is changed by adjusting the position of the Fourier-transformed Airy ring light field to adapt to the position of the obstacle.

[0083] Furthermore, in one embodiment, it also includes:

[0084] The angle of the bottle beam can be changed by adjusting the focal length of the lens.

[0085] Furthermore, in one embodiment, the complex amplitudes of a square Airy ring and a circular Airy ring after Fourier transformation are written into the spatial light modulator to achieve space division multiplexing of spatial light.

[0086] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0087] It should be noted that, in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0088] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A polarization-independent spatial light obstacle avoidance system, characterized in that: The polarization-independent spatial light obstacle avoidance system comprises: light source; A dual polarization component, comprising an optical path element and a spatial light modulator, wherein the optical path element is used to split the incident light output by the light source into two polarized lights and convert them into target polarized light modulatable by the spatial light modulator, wherein the spatial light modulator is written with the complex amplitude of at least one Airy ring after Fourier transformation to modulate the target polarized light; A lens generates a bottle beam for obstacle avoidance based on the target polarized light modulated by the spatial light modulator.

2. The polarization-independent spatial light obstacle avoidance system according to claim 1, characterized in that: The optical path element comprises: A beam splitter prism, which is used to receive the incident light output by the light source; A polarization beam splitter prism, used to split the light beam output by the beam splitter prism into two orthogonal polarized lights; A reflector assembly, comprising a first branch and a second branch, wherein the first branch is provided with a first reflector, and the first reflector is used to directly input a polarized light into the spatial light modulator, and the first branch is provided with a second reflector and a half-wave plate, and the second reflector is used to input another polarized light into the half-wave plate for conversion, and then input into the spatial light modulator; The reflector assembly is also used to receive the light beam modulated by the spatial light modulator and output it to the lens through the beam splitter prism.

3. The polarization-independent spatial light obstacle avoidance system according to claim 1, characterized in that: The light source is a collimated light source, and the collimated light source includes a laser and a collimator.

4. A polarization-independent spatial light obstacle avoidance method using the polarization-independent spatial light obstacle avoidance system according to claim 1, characterized in that: The polarization-independent spatial light obstacle avoidance method comprises: The dual polarization component is used to split the incident light output by the light source into two polarized lights, and convert them into target polarized lights that can be modulated by the spatial light modulator; Modulating the target polarized light using the spatial light modulator and generating a bottle-shaped beam through a lens; The position and size of the bottle body of the bottle beam are adjusted so that the obstacle is located inside the bottle beam and is smaller than the bottle body.

5. The polarization-independent spatial light obstacle avoidance method according to claim 4, characterized in that: The complex amplitude expression of the Airy ring is: Among them, Ai is the Airy function, r0(θ) is the polar coordinate expression of the ring shape, r is the polar distance, θ is the polar angle, w is the scale factor, and a is the attenuation factor; The size of the bottle can be changed by adjusting r0(θ).

6. The polarization-independent spatial light obstacle avoidance method according to claim 5, characterized in that: When the bottle body is not circular, the scale factor w is set to So that light beams with different r0(θ) can be focused to the same point, where f is the focusing distance and k is the wave vector.

7. The polarization-independent spatial light obstacle avoidance method according to claim 4, characterized in that: A beam splitter grating is used to make the phase written into the spatial light modulator satisfy: in, A is the amplitude, is the phase, is the grating phase, and Mod means remainder.

8. The polarization-independent spatial light obstacle avoidance method according to claim 4, characterized in that: Also includes: The position of the bottle is changed by adjusting the position of the Fourier-transformed Airy ring light field to adapt to the position of the obstacle.

9. The polarization-independent spatial light obstacle avoidance method according to claim 4, characterized in that: Also includes: The angle of the bottle beam can be changed by adjusting the focal length of the lens.

10. The polarization-independent spatial light obstacle avoidance method according to claim 4, characterized in that: The complex amplitudes of a square Airy ring and a circular Airy ring after Fourier transformation are written into the spatial light modulator to realize space division multiplexing of spatial light.

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