Polarization independent spatial light obstacle avoidance system and method

Abstract

This application relates to a polarization-independent spatial optical obstacle avoidance system and method, belonging to the field of optical communication technology. The polarization-independent spatial optical obstacle avoidance system includes: a light source; a dual-polarization component, which includes an optical path element and a spatial light modulator. The optical path element is used to split the incident light output from the light source into two polarized lights and convert them into target polarized light modulated by the spatial light modulator. The spatial light modulator is programmed with at least one complex amplitude of an Airy ring after Fourier transform to modulate the target polarized light; and a lens, which generates a bottle-shaped beam for obstacle avoidance based on the target polarized light modulated by the spatial light modulator. This application can process signals with arbitrary polarization states and simultaneously use the bottle-shaped beam to bypass obstacles at designated locations, ensuring the efficiency and quality of signal transmission.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, specifically to a polarization-independent spatial optical obstacle avoidance system and method. Background Technology

[0002] With the increasing demand for bandwidth and high data rates in heterogeneous networks, 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 bands of the electromagnetic spectrum are limited in capacity, and most sub-bands are proprietary and expensive. In contrast, space optical links offer higher available optical bandwidth, enabling faster communication rates. Space optical communication uses lasers as carriers, offering advantages such as resistance to electromagnetic interference and strong confidentiality; it operates in frequency bands above 300 GHz, which are unregulated globally, requiring no additional costs; it is easy to deploy, can be reinstalled, and eliminates the cost of dedicated fiber optic connections. Space optical communication is highly attractive in applications such as MAN (Metropolitan Area Network) expansion, 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 communication is its susceptibility to beam obstructions, which are typically on the same order of magnitude as the beam diameter and can cause power loss or link interruption. Summary of the Invention

[0005] This application provides a polarization-independent spatial light obstacle avoidance system and method that can process signals in any polarization state, while using a bottle-shaped beam to bypass obstacles at a specified location, ensuring the efficiency and quality of signal transmission.

[0006] In a first aspect, embodiments of this application provide a polarization-independent spatial optical obstacle avoidance system, the polarization-independent spatial optical obstacle avoidance system comprising:

[0007] light source;

[0008] A dual polarization component includes an optical path element and a spatial light modulator. The optical path element is used to split the incident light output from the light source into two polarized lights and convert them into target polarized light that can be modulated by the spatial light modulator. The spatial light modulator is written with at least one complex amplitude of an Airy ring after Fourier transform to modulate the target polarized light.

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

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

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

[0012] A polarizing beam splitter, used to split the beam output by the beam splitter into two orthogonally polarized beams;

[0013] A reflector assembly includes a first branch and a second branch. The first branch is provided with a first reflector for directly inputting one polarized light into the spatial light modulator. The first branch is provided with a second reflector and a half-wave plate for inputting another polarized light into the half-wave plate for conversion before inputting it 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.

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

[0016] Secondly, embodiments of this application provide a polarization-independent spatial light obstacle avoidance method, the polarization-independent spatial light obstacle avoidance method comprising:

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

[0018] The spatial light modulator is used to modulate the target polarized light, and a bottle-shaped beam is generated through a lens;

[0019] Adjust the position and size of the bottle-shaped beam so that the obstacle is inside the bottle-shaped beam and its size is smaller than the bottle body.

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

[0021] The complex amplitude expression of the Airy ring is: Where Ai is the Airy function, r0(θ) is the polar coordinate expression of the ring shape, r is the polar moment, θ is the polar angle, w is the scaling factor, and a is the decay factor;

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

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

[0024] When the bottle body is not circular, the scaling factor w is set to... So that 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 embodiment, a beam-splitting grating is used to ensure that the phase written into the spatial light modulator satisfies:

[0026] in, A is the amplitude. For phase, The phase of the grating is represented by Mod, which indicates the remainder.

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

[0028] The position of the bottle body is changed by adjusting the position of the Airy ring light field that undergoes Fourier transform to adapt to the position of the obstacle.

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

[0030] The angle of the bottle-shaped beam is changed by adjusting the focal length of the lens.

[0031] In conjunction with the second aspect, in one embodiment, the complex amplitude of a square Airy ring and a circular Airy ring after Fourier transform is written into the spatial light modulator to achieve spatial multiplexing of spatial light.

[0032] The beneficial effects of the technical solutions provided in this application include:

[0033] The polarization-independent spatial light obstacle avoidance system in this application uses a dual polarization component to split the incident light output from the light source into two polarized lights and convert them into target polarized light that can be modulated by a spatial light modulator; the target polarized light is modulated by a spatial light modulator with a complex amplitude written with at least one Airy ring after Fourier transform, and a bottle-shaped beam is generated through a lens; the position and size of the bottle-shaped beam are adjusted so that the obstacle is located inside the bottle-shaped beam and its size is smaller than the bottle body.

[0034] This application uses a dual polarization component to split the incident light into two polarized components, processes each component separately, and then combines them, thereby reducing the impact of polarization on system performance. This allows for the processing of signals with arbitrary polarization states, while using a bottle-shaped beam to bypass obstacles at designated locations, ensuring both efficiency and quality of signal transmission. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

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

[0037] Figure 2 This is a schematic diagram of the structure of an embodiment of the dual polarization component of this application;

[0038] Figure 3 This is a schematic diagram of the arrangement of the two Airy rings in this application;

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

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

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

[0042] Figure 7 This is a schematic diagram illustrating the propagation process of the delayed bottle in this application;

[0043] Figure 8 This is a schematic diagram of the propagation process of the bottle-shaped light beam from an outward angle according to this application.

[0044] Figure 9 This is a flowchart of an embodiment of the polarization-independent spatial light obstacle avoidance method of this application. Detailed Implementation

[0045] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0046] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0047] In a first aspect, embodiments of this application provide a polarization-independent spatial light obstacle avoidance system.

[0048] In one embodiment, reference is made to Figure 1 , Figure 1 This is a structural block diagram of an embodiment of the polarization-independent spatial optical obstacle avoidance system of this 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 this 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. This embodiment does not impose any restrictions on this.

[0050] The dual polarization assembly includes an optical path element and a spatial light modulator. The optical path element splits the incident light output from the light source into two polarized beams and converts them into target polarized light modulated by the spatial light modulator. The spatial light modulator is programmed with the complex amplitude of at least one Fourier-transformed Airy ring 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 components include a beam splitter prism, a polarizing beam splitter prism, and a mirror assembly.

[0052] A beam splitter is used to receive the incident light output from the light source, and a polarizing beam splitter is used to split the beam output from the beam splitter into two orthogonally polarized beams.

[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 one 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 it into the spatial light modulator. The reflector assembly is also used to receive the beam modulated by the spatial light modulator and output it to the lens through a beam splitter.

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

[0055] It is understood that this embodiment uses a polarizing beam splitter to split the light into two orthogonal polarization components, processes these two components separately, and then combines them. This reduces the impact of polarization on system performance and thus achieves polarization independence.

[0056] The principle of a polarization-independent spatial optical 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 used as an example. Since a 1550nm light source is invisible to the naked eye, when adjusting the dual-polarized optical path, the optical path should first be roughly adjusted using visible light, and then the optical path should be fine-tuned by observing the beam using a CCD (Charge-Coupled Device) to ensure that the dual-polarized light is incident on the same position on the spatial light modulator and that the beams overlap when exiting from the dual-polarized part.

[0058] The specific fine-tuning steps are as follows: First, load a vortex phase onto the spatial light modulator. Place the CCD between the first reflector on the left and the spatial light modulator, and adjust the optical path so that a standard ring can be observed on the CCD. This indicates that the polarized light is at the center of the loaded phase. Then, place the CCD between the second reflector on the right and the spatial light modulator. Repeat the above steps to ensure that the dual-polarized light is incident on the same position on the spatial light modulator. When adjusting the overlap of the outgoing beams, place the CCD between the dual-polarization component and the lens, and adjust the optical path until only one spot is observed on the CCD. Since adjusting the optical path affects the positions of both the incident and outgoing light, the above steps need to be performed multiple times. To verify the accuracy of the final optical path, a polarization controller can be added in front of the collimating source to change the polarization state of the laser. If the outgoing light does not change, it indicates that the system is polarization-independent.

[0059] The complex amplitude expression for an Airy ring is: Where Ai is the Airy function, r0(θ) is the polar coordinate expression of the ring shape, r is the polar moment, θ is the polar angle, w is the scaling factor, and a is the decay factor.

[0060] Multiple Airy rings of different shapes are arranged in space, and then a Fourier transform is performed. The transformed complex amplitude is written into a spatial light modulator. After the beam passes through the spatial light modulator, a bottle-shaped beam is generated at the focal plane of the lens. See also Figure 3 As shown, this embodiment uses two Airy rings as an example, with the left one being square and the right one circular. The propagation process is as follows: Figure 4 As shown, the upper part is a square bottle body, and the lower part is a circular bottle body. The dashed line represents the lens position. As the propagation distance increases, the bottle-shaped beam gradually closes and eventually evolves into a Bezier-like beam, with its focused light field as shown... Figure 5 As shown, when an obstacle is located inside the bottle-shaped beam and its size is smaller than the bottle body, the spatial light can bypass the obstacle unaffected.

[0061] Based on the complex amplitude expression of the Airy ring, it can be seen that the size of the bottle can be changed by adjusting r0(θ), thus adapting to obstacles of different sizes. If the bottle is circular, r0(θ) is a constant. When the bottle has other shapes (non-circular), the scaling factor w is set to... So that 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] Current spatial light modulators can only modulate either the phase or the amplitude, not both simultaneously. When using a phase-only spatial light modulator, to simultaneously write both amplitude and phase, the principle of a beam splitter is used to ensure the phase satisfies:

[0063] in, A is the amplitude. For phase, The phase of the grating is represented by Mod, which indicates the remainder.

[0064] For details on the phase superposition process, please refer to Figure 6 As shown, the first image represents the graph of M, the second image represents F, and the third image represents... Addition means The final multiplication represents the required phase: Since the phase has a period of 2π, and The images are the same image.

[0065] Furthermore, by applying angular spectrum theory, a Fourier transform of the complex amplitude of the Airy ring light field after propagation a distance z in the forward / backward direction is written into a spatial light modulator, which can change the position of the bottle to adapt to the position of the obstacle. The propagation process of the ring-shaped bottle is delayed as follows: Figure 7 As shown. Changing the focal length of the lens can change the angle of the bottle-shaped beam. For example... Figure 8 As shown, appropriately increasing the focal length of the lens can make the angle of the two bottle-shaped beams point outwards.

[0066] Understandably, the above operations can change the angle of the bottle-shaped beam, the size of the bottle, and its position, thereby better adapting to obstacles and completing obstacle avoidance.

[0067] In summary, the polarization-independent spatial light obstacle avoidance system of this application uses a dual polarization component to split the incident light output from the light source into two polarized lights and convert them into target polarized light that can be modulated by a spatial light modulator; the target polarized light is modulated by a spatial light modulator with a complex amplitude written with at least one Airy ring after Fourier transform, and a bottle-shaped beam is generated through a lens; the position and size of the bottle-shaped beam are adjusted so that the obstacle is located inside the bottle-shaped beam and its size is smaller than the bottle body.

[0068] This application uses a dual polarization component to split the incident light into two polarized components, processes each component separately, and then combines them, thereby reducing the impact of polarization on system performance. This allows for the processing of signals with arbitrary polarization states, while using a bottle-shaped beam to bypass obstacles at designated locations, ensuring both efficiency and quality of signal transmission.

[0069] Secondly, embodiments of this application provide a polarization-independent spatial light obstacle avoidance method.

[0070] In one embodiment, reference is made to Figure 9 , Figure 9 This is a flowchart illustrating an embodiment of the polarization-independent spatial light obstacle avoidance method of this application. Figure 9 As shown, polarization-independent spatial light obstacle avoidance methods include:

[0071] S1. The incident light output from the light source is split into two polarized lights using the dual polarization component and converted into target polarized light that can be modulated by the spatial light modulator.

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

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

[0074] Furthermore, in one embodiment,

[0075] The complex amplitude expression of the Airy ring is: Where Ai is the Airy function, r0(θ) is the polar coordinate expression of the ring shape, r is the polar moment, θ is the polar angle, w is the scaling factor, and a is the decay 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 scaling factor w is set to... So that 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-splitting grating is used to ensure that the phase written into the spatial light modulator satisfies:

[0080] in, A is the amplitude. For phase, The phase of the grating is represented by Mod, which indicates the remainder.

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

[0082] The position of the bottle body is changed by adjusting the position of the Airy ring light field that undergoes Fourier transform to adapt to the position of the obstacle.

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

[0084] The angle of the bottle-shaped beam is changed by adjusting the focal length of the lens.

[0085] Furthermore, in one embodiment, the complex amplitude obtained by Fourier transforming a square Airy ring and a circular Airy ring is written into the spatial light modulator to achieve spatial multiplexing of spatial light.

[0086] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this 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 used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0088] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A polarization-independent spatial optical obstacle avoidance system, characterized in that, The polarization-independent spatial optical obstacle avoidance system includes: light source; A dual polarization component includes an optical path element and a spatial light modulator. The optical path element is used to split the incident light output from the light source into two polarized lights and convert them into target polarized light that can be modulated by the spatial light modulator. The spatial light modulator is written with at least one complex amplitude of an Airy ring after Fourier transform to modulate the target polarized light. A lens that generates a bottle-shaped beam for obstacle avoidance based on target polarized light modulated by the spatial light modulator; The complex amplitude expression of the Airy ring is as follows: ,in, For Airy functions, Let be the polar coordinate expression for the ring shape. For polar distance, Polar angle, As a scaling factor, It is the attenuation factor; And the phase written into the spatial light modulator satisfies: ,in, , For amplitude, , For phase, For grating phase, Indicates taking the remainder.

2. The polarization-independent spatial optical obstacle avoidance system as described in claim 1, characterized in that, The optical path element includes: A beam splitter prism is used to receive the incident light output from the light source; A polarizing beam splitter, used to split the beam output by the beam splitter into two orthogonally polarized beams; A 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 one polarized light into the spatial light modulator. The second 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 it 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.

3. The polarization-independent spatial optical obstacle avoidance system as described in claim 1, characterized in that: The light source is a collimated light source, which includes a laser and a collimator.

4. A polarization-independent spatial optical obstacle avoidance method utilizing the polarization-independent spatial optical obstacle avoidance system of claim 1, characterized in that, The polarization-independent spatial light obstacle avoidance method includes: The dual polarization component is used to split the incident light output from the light source into two polarized lights, and then convert them into target polarized light that can be modulated by the spatial light modulator. The spatial light modulator is used to modulate the target polarized light, and a bottle-shaped beam is generated through a lens; Adjust the position and size of the bottle-shaped beam so that the obstacle is inside the bottle-shaped beam and its size is smaller than the bottle body.

5. The polarization-independent spatial optical obstacle avoidance method as described in claim 4, characterized in that: When the bottle body is not circular, the aforementioned scaling factor is set. for To make different The beam of light can be focused to the same point, where, To focus on distance, For wave vectors.

6. The polarization-independent spatial optical obstacle avoidance method as described in claim 4, characterized in that, Also includes: The position of the bottle body is changed by adjusting the position of the Airy ring light field that undergoes Fourier transform to adapt to the position of the obstacle.

7. The polarization-independent spatial optical obstacle avoidance method as described in claim 4, characterized in that, Also includes: The angle of the bottle-shaped beam is changed by adjusting the focal length of the lens.

8. The polarization-independent spatial optical obstacle avoidance method as described in claim 4, characterized in that: The complex amplitudes obtained by Fourier transforming a square Airy ring and a circular Airy ring are written into the spatial light modulator to achieve spatial multiplexing of spatial light.

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