A mechanical optical field manipulation method and system based on spatial frequency multiplexing

Abstract

This application relates to a mechanical optical field modulation method and system based on spatial frequency multiplexing, belonging to the field of optical communication. The method includes the following steps: loading multiple target spatial optical field distributions one-to-one into different spatial frequency distributions; obtaining a phase distribution map through a holographic multiplexing algorithm; fabricating a phase control panel based on the phase distribution map; placing an electrically adjustable aperture in the Fourier space behind the phase control panel and aligning it with the optical signal of the spatial frequency; irradiating the phase control panel with a single-wavelength laser; and moving and scanning the laser in space by adjusting the size or position of the aperture on the electrically adjustable aperture. This application adopts a combination of phase modulation and mechanical control, which is cheaper than a purely mechanical adjustment method and faster than a purely phase modulation method, thus ensuring optical modulation speed while maintaining a lower overall device cost.

Description

Technical Field

[0001] This application relates to the field of optical communication, specifically to a mechanical optical field modulation method and system based on spatial frequency multiplexing. Background Technology

[0002] Optical field manipulation technology enables the scanning of light positions in space, thus having important applications in fields such as lidar and wireless optical communication. The key to the commercial application of optical field manipulation technology lies in its high-speed optical field modulation and low overall device cost.

[0003] Currently, most optical field modulation techniques are based on the principle of optical field wavefront (i.e., phase distribution) modulation, such as using phase-modulated liquid crystals (e.g., silicon-based liquid crystals) and integrated optical waveguide phase modulators (e.g., integrated optical chips). However, the modulation speed of beam deflection control methods based on silicon-based liquid crystals is relatively slow.

[0004] In contrast, mechanical optical field manipulation techniques, such as those using vibrating mirrors, offer faster control. However, micro-vibrating mirror arrays, such as MEMS, are complex to fabricate and expensive. Summary of the Invention

[0005] This application provides a mechanical optical field modulation method and system based on spatial frequency reuse to solve the problem that optical field modulation speed and overall device cost cannot be simultaneously achieved in related technologies.

[0006] Firstly, a mechanical optical field manipulation method based on spatial frequency reuse is provided, including the following steps:

[0007] Multiple target spatial light field distributions are loaded one-to-one into different spatial frequency distributions, and a phase distribution map is obtained through a holographic multiplexing algorithm. A phase control panel is then prepared based on the phase distribution map.

[0008] The electrically adjustable aperture is placed in the Fourier space behind the phase control panel and aligned with the optical signal of the spatial frequency.

[0009] A single-wavelength laser is irradiated onto the phase control panel, and the laser can be moved and scanned in space by adjusting the size or position of the aperture on the electrically adjustable aperture.

[0010] In some embodiments, the distribution of multiple target spatial light fields is obtained based on the spatial range that the light field needs to be scanned according to the application scenario.

[0011] In some embodiments, obtaining the phase distribution map using a holographic multiplexing algorithm includes:

[0012] The amplitudes of multiple target spatial light field distributions are extracted, and combined with the phase of the first spatial light field distribution obtained by calculation, multiple phase distributions are obtained through the reverse spatial light propagation function;

[0013] The inverse spatial light propagation function applied to a target spatial light field distribution contains only one spatial frequency corresponding to the spatial range.

[0014] The first spatial light field is calculated based on the forward spatial light propagation function.

[0015] In some embodiments, the forward spatial light propagation function includes an iterative phase distribution. according to

[0016]

[0017] The forward spatial light propagation function is obtained by initially using a random phase distribution.

[0018] On the other hand, a mechanical optical field manipulation system based on spatial frequency multiplexing is provided, comprising:

[0019] A light source assembly used to provide a single wavelength of laser light;

[0020] A phase control panel is used to generate a corresponding phase distribution based on the target spatial light field distribution. The phase control panel loads multiple target spatial light field distributions one-to-one onto different spatial frequency distributions, obtains a phase distribution map through a holographic multiplexing algorithm, and prepares the phase distribution map based on the phase distribution map.

[0021] There are two Fourier lenses, which form a Fourier space between them. The Fourier space is located behind the phase control panel.

[0022] An electrically adjustable aperture is disposed within the Fourier space and aligned with the optical signal of the spatial frequency; it is used to enable the laser to move and scan in space by adjusting the size or position of the aperture.

[0023] In some embodiments, the light source assembly includes:

[0024] A laser, used to maintain the same wavelength output;

[0025] A collimator is used to adjust the light emitted by a laser to near-planar light.

[0026] A linear polarizer is used to control the polarization of laser light.

[0027] In some embodiments, the laser is a single-wavelength laser;

[0028] Alternatively, the laser may be a combination of a multi-wavelength laser and a filter.

[0029] In some embodiments, of the two Fourier lenses, the Fourier lens adjacent to the phase control panel is the first Fourier lens, which is used to convert spatial optical signals into Fourier space; the electrically adjustable aperture is located at the focal plane of the first Fourier lens.

[0030] Another Fourier lens is the second Fourier lens, which is used to convert the optical signal in Fourier space into a light field distribution in space.

[0031] In some embodiments, the phase control panel employs a silicon-based liquid crystal spatial light modulator, a diffractive optical element, or a metasurface.

[0032] In some embodiments, the target spatial light field distribution is obtained based on the spatial range that the light field needs to be scanned according to the application scenario;

[0033] The phase distribution map obtained through the holographic multiplexing algorithm includes:

[0034] The amplitudes of multiple target spatial light field distributions are extracted, and combined with the phase of the first spatial light field distribution obtained by calculation, multiple phase distributions are obtained through the reverse spatial light propagation function;

[0035] The reverse spatial light propagation function only includes the spatial frequencies corresponding to the spatial range;

[0036] The first spatial light field is calculated based on the forward spatial light propagation function.

[0037] The beneficial effects of the technical solution provided in this application include:

[0038] The desired spatial position of the light is loaded into different spatial frequency light signals to fabricate a corresponding phase control panel. An electrically driven variable aperture is then placed in the Fourier plane after the phase control panel. By adjusting the size and position of the aperture of the electrically driven variable aperture, the laser can move and scan in space. The phase control panel and the electrically driven variable aperture are inexpensive, thus reducing the cost of the optical field manipulation system. Furthermore, a mechanically moving variable aperture is used, which can be controlled by a conventional motor and is easy to implement. This application employs a combination of phase modulation and mechanical control, which is cheaper than purely mechanical adjustment methods and faster than purely phase modulation methods, thus ensuring both high optical modulation speed and low overall device cost. Attached Figure Description

[0039] 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.

[0040] Figure 1 This is a flowchart of a mechanical optical field manipulation method based on spatial frequency reuse, as described in an embodiment of the present invention.

[0041] Figure 2 This is a schematic diagram of the phase distribution map calculated according to an embodiment of the present invention;

[0042] Figure 3 This is a schematic diagram of a mechanical optical field manipulation system based on spatial frequency reuse, according to an embodiment of the present invention.

[0043] Figure label:

[0044] 1. Laser; 2. Collimator; 3. Linear polarizer; 4. Phase control panel; 5. First Fourier lens; 6. Motorized adjustable aperture; 7. Second Fourier lens. Detailed Implementation

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

[0046] This application provides an embodiment of a mechanical optical field manipulation method based on spatial frequency reuse. The desired spatial position of the optical field is loaded into different spatial frequency regions through a phase control panel, and this process is designed by computer calculation. The motorized variable aperture selects the spatial frequency region and range at the Fourier plane after the phase control panel, thereby realizing the manipulation of the position of the optical field in the free space thereafter.

[0047] like Figure 1 As shown, the mechanical optical field manipulation method based on spatial frequency reuse includes:

[0048] S1. Multiple target spatial light field distributions are loaded one-to-one into different spatial frequency distributions. A phase distribution map is obtained through a holographic multiplexing algorithm, and a phase control panel is prepared based on the phase distribution map. Specifically, the spatial range that the light field needs to be scanned is determined according to the application scenario, thereby obtaining multiple target spatial light field distributions. The holographic multiplexing algorithm is based on the common Gerchberg-Saxton algorithm.

[0049] S2. Place the electrically adjustable aperture in the Fourier space behind the phase control panel and align it with the optical signal of the spatial frequency.

[0050] S3. Irradiate a single-wavelength laser onto the phase control panel, and move and scan the laser in space by adjusting the size or position of the aperture on the electrically adjustable aperture.

[0051] In step S1 above, the process of calculating the phase distribution map can be completed on a computer. For example... Figure 2 As shown, the specific calculation process is as follows:

[0052] Extracting the amplitude of the spatial light field distribution of multiple targets (e.g.) Figure 2 Given target spatial light field distribution 1, target spatial light field distribution 2, ..., target spatial light field distribution n), and combining the phase of the first spatial light field distribution obtained through calculation, multiple phase distributions are obtained through the reverse spatial light propagation function, such as... Figure 2 Mid-phase distribution Phase distribution ...phase distribution Specifically, the reverse spatial light propagation function applied to a target spatial light field distribution contains only the spatial frequency corresponding to the spatial range in step 1. Furthermore, the first spatial light field is calculated based on the forward spatial light propagation function, initially using a random initial phase distribution, and subsequently based on...

[0053]

[0054] Obtain the phase distribution for each iteration

[0055] Compared to traditional algorithms, the above calculation uses the spatial light propagation formula—the angular spectrum method—and calculates only a portion of the angular spectrum for each target spatial light field distribution. This allows each target spatial light field distribution to be loaded into different spatial frequencies on the Fourier plane. Therefore, this algorithm allows for the selection of different spatial frequencies simply by adjusting the position of the light aperture on the electrically adjustable aperture in the Fourier plane, thereby enabling the switching between different spatial light field distributions.

[0056] like Figure 3As shown, this application also provides an embodiment of a mechanical optical field manipulation system based on spatial frequency multiplexing, which can be implemented independently or used to implement the above method. The system includes a light source assembly, a phase control panel 4, two Fourier lenses, and an electrically adjustable aperture 6.

[0057] The light source assembly provides a single-wavelength laser. Specifically, the light source assembly includes a laser 1, a collimator 2, and a linear polarizer 3. The laser 1 maintains a single wavelength output, which can be any wavelength. The laser 1 can be a single-wavelength laser or a combination of multi-wavelength lasers and filters. The collimator 2 is positioned after the laser 1 to adjust the emitted light to near-planar light, ensuring that the light illuminating the phase control panel 4 is approximately planar. The linear polarizer 3 is positioned after the collimator to control the polarization of the laser.

[0058] The phase control panel 4 is used to generate a corresponding phase distribution based on the target spatial light field distribution. The phase control panel 4 loads multiple target spatial light field distributions one-to-one into different spatial frequency distributions, and obtains a phase distribution map through a holographic multiplexing algorithm. The phase distribution map is prepared in advance based on the phase distribution map.

[0059] Of the two Fourier lenses mentioned above, the Fourier lens adjacent to the phase control panel 4 is the first Fourier lens 5, and the other Fourier lens is the second Fourier lens 7. A Fourier space is formed between the first Fourier lens 5 and the second Fourier lens 7, and the Fourier space is located behind the phase control panel 4. The first Fourier lens 5 is used to convert spatial optical signals to Fourier space, and the second Fourier lens 7 is used to convert optical signals in Fourier space into a light field distribution in space.

[0060] The electrically adjustable aperture 6 is located within Fourier space and at the focal plane of the first Fourier lens, meaning it is aligned with the spatial frequency optical signal. The size or position of the aperture of the electrically adjustable aperture 6 can be rapidly controlled by a motor; by adjusting the size or position of the aperture, the laser can move and scan in space. Depending on the different spatial frequency light information transmitted through the electrically adjustable aperture 6, the spatial distribution of the light field behind the second Fourier lens 7 varies, thus achieving the function of controlling the direction of light field propagation.

[0061] Preferably, the phase control panel 4 can be a phase control device such as a silicon-based liquid crystal spatial light modulator, a diffractive optical element, or a metasurface.

[0062] Preferably, the overall calculation of the phase distribution map can be performed on a computer. Based on the spatial range that the light field needs to be scanned according to the application scenario, the target spatial light field distribution is obtained. The amplitudes of multiple target spatial light field distributions are extracted, and then combined with the phase of the calculated first spatial light field distribution. Multiple phase distributions are obtained through the reverse spatial light propagation function. Specifically, the reverse spatial light propagation function applied to a target spatial light field distribution contains only the spatial frequency corresponding to one spatial range; the first spatial light field is calculated based on the forward spatial light propagation function, and the phase used in the forward spatial light propagation function is obtained through... get.

[0063] This application uses a combination of phase modulation and mechanical control, which is cheaper than purely mechanical adjustment and faster than purely phase modulation.

[0064] 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.

[0065] 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 mechanical light field modulation method based on spatial frequency multiplexing, characterized in that, The method comprises the steps of: loading a plurality of target spatial light field distributions one by one into different spatial frequency distributions, obtaining a phase distribution map through a holographic multiplexing algorithm, and preparing a phase control panel according to the phase distribution map; placing an electrically adjustable diaphragm in the Fourier space behind the phase control panel and aligning the electrically adjustable diaphragm with the spatial frequency light signal; irradiating single-wavelength laser on the phase control panel, and adjusting the size or position of the aperture of the electrically adjustable diaphragm to realize the movement and scanning of the laser in space.

2. The mechanical light field manipulation method based on spatial frequency multiplexing according to claim 1, wherein, The plurality of target spatial light field distributions are obtained according to the spatial range that needs to be scanned by the light field according to the application scenario.

3. The mechanical light field manipulation method based on spatial frequency multiplexing according to claim 2, wherein, The method of obtaining the phase distribution map through the holographic multiplexing algorithm comprises the steps of: extracting the amplitudes of the plurality of target spatial light field distributions, combining the calculated phase of the first spatial light field distribution, and obtaining a plurality of phase distributions through an inverse spatial light propagation function; the inverse spatial light propagation function applied to a target spatial light field distribution only contains a spatial frequency corresponding to the spatial range; the first spatial light field is calculated according to a forward spatial light propagation function.

4. The mechanical light field manipulation method based on spatial frequency multiplexing according to claim 3, wherein, The forward spatial light propagation function comprises an iterative phase distribution According to The forward spatial light propagation function initially adopts a random phase distribution.

5. A mechanical light field modulation system based on spatial frequency multiplexing, characterized in that, The method comprises the steps of: a light source assembly for providing single-wavelength laser; a phase control panel for generating a corresponding phase distribution according to a target spatial light field distribution; the phase control panel is prepared according to a phase distribution map obtained by loading a plurality of target spatial light field distributions one by one into different spatial frequency distributions through a holographic multiplexing algorithm; two Fourier lenses, forming a Fourier space between the two Fourier lenses, the Fourier space being located behind the phase control panel; an electrically adjustable diaphragm arranged in the Fourier space and aligned with the spatial frequency light signal; for realizing the movement and scanning of the laser in space by adjusting the size or position of the aperture of the light hole.

6. The spatial frequency multiplexing based mechanical light field modulation system of claim 5, wherein, The light source assembly comprises: a laser for maintaining the same wavelength output; a collimator for adjusting the light emitted by the laser to be close to plane light; a linear polarizer for controlling the polarization of the laser.

7. The spatial frequency multiplexing based mechanical light field modulation system of claim 6, wherein, The laser is a single-wavelength laser; alternatively, the laser is a combination of a multi-wavelength laser and a filter.

8. The spatial frequency multiplexing based mechanical light field modulation system of claim 5, wherein, In the two Fourier lenses, the Fourier lens adjacent to the phase control panel is a first Fourier lens, and the first Fourier lens is used to convert the spatial optical signal to the Fourier space; the electrically adjustable diaphragm is located at the focal plane of the first Fourier lens; the other Fourier lens is a second Fourier lens, which is used to convert the optical signal in the Fourier space to the light field distribution in space.

9. The spatial frequency multiplexing based mechanical light field modulation system of claim 5, wherein, The phase control panel adopts a liquid crystal on silicon spatial light modulator, a diffractive optical element or a metasurface.

10. The spatial frequency multiplexing based mechanical light field modulation system of claim 5, wherein, The target spatial light field distribution is obtained according to the spatial range that needs to be scanned by the light field according to the application scenario; The method of obtaining the phase distribution map through the holographic multiplexing algorithm comprises the steps of: extracting the amplitudes of the plurality of target spatial light field distributions, combining the calculated phase of the first spatial light field distribution, and obtaining a plurality of phase distributions through an inverse spatial light propagation function; the inverse spatial light propagation function only contains a spatial frequency corresponding to the spatial range; The first spatial light field is calculated according to a forward spatial light propagation function. The first spatial light field is calculated according to a forward spatial light propagation function.

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