Spectrum processing system, processing method and medium
By combining a liquid crystal spatial light modulator and a spectral detector, and employing a polarization-independent design and a metasurface layer, the problem of separating the spectral shaper from the spectrometer is solved, achieving high-precision integrated spectral detection and shaping, simplifying the optical path, and supporting simultaneous processing of multiple spectra.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-09
- Publication Date
- 2026-04-03
AI Technical Summary
In the prior art, the spectral shaper and the spectrometer are separate systems, which leads to complex optical paths and low measurement accuracy. Furthermore, the polarization dependence of liquid crystal on silicon (LCoS) limits the realization of spectral detection and shaping in the same spatial optical path.
Design a spectral processing system that combines a liquid crystal spatial light modulator and a spectral detector. Employ a polarization-independent liquid crystal spatial light modulator and a metasurface layer to achieve simultaneous spectral detection and shaping. A beam splitter separates the light beam into shaping and detection beams, and the metasurface layer is used to rotate the polarization direction to achieve polarization-independent phase modulation.
It integrates spectral detection and shaping, simplifies the optical path structure, improves measurement accuracy, reduces costs, and supports simultaneous processing of multiple spectra and closed-loop monitoring.
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Figure CN121783338A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of optical signal processing technology, and in particular to a spectral processing system, processing method and medium. Background Technology
[0002] Precise control of the spectral characteristics of optical signals is a prerequisite for better application of light. Spectral shapers can arbitrarily filter input light, control spectral attenuation and phase, and output light of different spectra to different ports. This capability allows for precise control of frequency domain waveforms, applicable to many scenarios, such as reducing dispersion and achieving pulse compression for laser pulses; in optical communication, the wavefront of different wavelengths can be modulated for wavelength selective switches (WSS); and in near-infrared spectral imaging, different filtering methods can be used to eliminate noise. In summary, spectral shapers have been widely used in industrial, medical, and communication fields. Currently common spectral shapers are based on spatial light modulators using Liquid Crystal on Silicon (LCoS). They utilize gratings to disperse light of different wavelengths onto a LCoS chip, where the LCoS performs filtering, selection, attenuation, and phase control of each wavelength, and the shaped light is output from a designated port.
[0003] Besides spectral shaping, spectral detection is also crucial, achieved using a spectrometer. Spectrometers come in various structures: for example, they employ dispersive optical elements such as diffraction gratings to direct light of different wavelengths onto spatially separated detectors, thus enabling spectral detection; or they utilize interferometers to modulate the light incident on a single detector over time, obtaining the detected spectrum through Fourier transform. Furthermore, spectrometers have a wide range of applications, serving not only as essential equipment for materials and chemical analysis but also as vital instruments in optical experiments.
[0004] Currently, spectral shapers and spectrometers are two separate systems. Optical experiments and tests require separate measurements and shaping of the spectrum using both a spectrometer and a spectral shaper. The components used in spectral shapers and spectrometers differ, and the liquid crystal on silicon (LCoS) in spectral shapers exhibits polarization dependence and contains polarization processing components. Therefore, current technology cannot support spectral detection and spectral shaping within the same spatial optical path. Summary of the Invention
[0005] The purpose of this application is to provide a spectral processing system, processing method, and medium, which aims to solve the technical problems of the separation of spectral shaping and detection equipment in the prior art, as well as the complexity of the optical path and low measurement accuracy caused by LCoS polarization correlation.
[0006] Firstly, the spectral processing system provided in this application adopts the following technical solution: A spectral processing system includes an optical front end, a relay lens group, a dispersive element, and a beam splitter arranged sequentially, wherein the beam splitter splits a light beam from the dispersive element into a first beam and a second beam. The system also includes: A liquid crystal spatial light modulator is disposed in the optical path of the first beam and has polarization-independent characteristics. It is used to perform phase and / or amplitude modulation processing on different wavelength components of the first beam and to reflect the processed beam along the original optical path for output via the optical front end. A spectral detector is placed in the optical path of the second beam to receive the second beam and detect its spectral power distribution to obtain spectral information.
[0007] Furthermore, the optical front end includes an optical port, a collimator, and a front cylindrical lens arranged sequentially; The optical ports are provided in multiple sets, and the photosensitive surfaces of the liquid crystal spatial light modulator and the spectral detector are divided into multiple regions, which correspond one-to-one with the multiple sets of optical ports. The beam splitter simultaneously projects beams from multiple optical ports onto corresponding areas of the liquid crystal spatial light modulator and the spectral detector, enabling simultaneous detection and shaping of multiple independent spectra.
[0008] Furthermore, the optical ports are provided in two sets, including a first port set and a second port set; The output port of the first port group is connected to the input port of the second port group via optical fiber coupling, so that the output light of the first port group after being shaped by the liquid crystal spatial light modulator is input into the system again for secondary detection or secondary shaping.
[0009] Furthermore, the liquid crystal spatial light modulator includes: basal layer; A liquid crystal phase modulation layer comprising liquid crystal molecules that can be deflected by voltage control; A metasurface layer, which is embedded between the substrate layer and the liquid crystal phase modulation layer, is used to reflect incident light and rotate its polarization direction; The metasurface layer includes multiple metasurface units arranged in an array, which are used to rotate the incident linearly polarized light by 90 degrees and reflect it, so that the two orthogonal polarization components undergo the same phase modulation.
[0010] Furthermore, the metasurface unit includes a reflective layer, a dielectric substrate, and a dielectric pillar arranged sequentially.
[0011] Furthermore, the relay lens assembly includes: The dispersive directional cylindrical lens has its back focal plane of the optical front end, the dispersive element, the liquid crystal spatial light modulator, and the spectral detector all disposed on the focal plane of the dispersive directional cylindrical lens. A port-direction column lens is disposed between the dispersive column lens and the dispersive element, and its focal length is approximately twice that of the dispersive column lens. The back focal plane of the optical front end, the liquid crystal spatial light modulator, and the spectral detector are located on the focal plane of the port-direction column lens. The liquid crystal spatial light modulator and the spectral detector are arranged conjugately relative to the beam splitter, and their optical path lengths after the beam splitter are equal, so that the light spot shapes received by both are the same.
[0012] Secondly, the spectral processing method provided in this application adopts the following technical solution: A spectral processing method, the method comprising the following steps: S100: After the input light is collimated and shaped by the optical front end, it is spatially dispersed according to wavelength by the dispersive element; S200: After the expanded input light is focused and transformed by the relay lens group, it is split by the beam splitter into a shaped beam that is transmitted to the liquid crystal spatial light modulator and a probe beam that is transmitted to the spectral detector. S300: The spectral detector receives the optical signal of the probe beam, records the optical power at each pixel position, and calculates the input spectrum based on the correspondence between pixel position and wavelength. S400: The shaping beam is incident on a polarization-independent liquid crystal spatial light modulator. The liquid crystal spatial light modulator, according to the preset shaping requirements, changes the refractive index of the liquid crystal by adjusting the voltage of each pixel, performs phase delay and / or attenuation on light of different wavelengths in the shaping beam, and controls the direction of the reflected light to couple it to the selected output port.
[0013] Furthermore, in step S300, the calculated input spectrum also includes a spectral restoration step: Constructing a degradation model: ; in, It is the observed light power at each pixel location. It is the optical power of the input light at each wavelength. It is a degradation function that is related to pixel spatial location and wavelength. The noise level is denoted by N, where N is the number of pixels in the dispersion direction of the spectral detector. This represents the spatial location of each pixel on the spectral detector. The wavelength; The measured optical power at each pixel location The optical power of each wavelength of the input light is obtained by deconvolution. To restore the input spectrum and improve spectral resolution.
[0014] Furthermore, in step S400, the polarization-independent processing includes: The incident light passes through the liquid crystal phase modulation layer for the first time and is subjected to the first phase modulation. When light waves reach the metasurface layer, the metasurface layer rotates the polarization state of the incident light by 90 degrees and reflects it. The reflected light passes through the liquid crystal phase modulation layer a second time and is modulated by a second phase. By rotating the polarization, the two orthogonal polarization components of the incident light undergo complementary modulation paths, thus achieving a total phase modulation that is independent of the polarization state of the incident light.
[0015] Thirdly, this application provides a computer-readable medium having a computer program stored thereon, which, when executed, implements the above-described method.
[0016] In summary, this application includes at least one of the following beneficial technical effects: 1. By integrating the spectral shaping optical system and the spectral detection optical system, high-precision spectral detection and spectral processing functions are achieved simultaneously, greatly simplifying the experimental setup and reducing costs.
[0017] 2. By introducing polarization-independent LCoS into the optical system, the polarization rotation characteristics of the metasurface are utilized to ensure that orthogonally polarized light undergoes the same phase modulation, thereby reducing the spectral detection error caused by polarization diversity and meeting the requirements for high-precision measurement.
[0018] 3. The system is extremely flexible. By deforming the optical system (such as a twin structure or a feedback structure), it can achieve simultaneous detection and shaping of multiple spectra, or perform closed-loop monitoring of the shaped spectrum, which greatly expands the application scenarios. Attached Figure Description
[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the 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.
[0020] Figure 1 This is the overall optical path diagram of the spectral processing system in Embodiment 1 of this application; Figure 2 This is a partial optical path diagram of the beam splitter, liquid crystal on silicon (LCoS), and spectral detector in this application; Figure 3This is a diagram showing the optical principle of the spectral processing system in the dispersion direction in this application. Figure 4 This is a schematic diagram of the optical principle of the spectral processing system in the port direction of this application. Figure 5 This is the overall optical path diagram of the Twin structure spectral processing system in Embodiment 2 of this application; Figure 6 This is the overall optical path diagram of the spectral processing with fiber-optic coupling feedback in Embodiment 3 of this application; Figure 7 This is a three-dimensional structural schematic diagram of the polarization-independent liquid crystal spatial light modulator in Embodiment 4 of this application; Figure 8 This is a performance curve showing the relationship between polarization conversion efficiency (PCR) and wavelength of the metasurface layer in Example 4 of this application.
[0021] In the diagram: 1. Optical port; 2. Collimator; 3. Front cylindrical lens; 4. Dispersion direction cylindrical lens; 5. Port direction cylindrical lens; 6. Diffraction grating; 7. Beam splitter; 8. Liquid crystal spatial light modulator; 9. Spectral detector. Detailed Implementation
[0022] The technical solution of this application will now be clearly and completely described with reference to the accompanying drawings. The following embodiments are exemplary and are only used to explain this application, and should not be construed as limiting this application. In the following description, the same reference numerals are used to denote the same or equivalent elements, and repeated descriptions are omitted.
[0023] In the description of this application, it should be understood that the terms "upper", "lower", "inner", "outer", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this application and to simplify the description, and are not intended to indicate or imply that the equipment or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.
[0024] Furthermore, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0025] It should also be further understood that the term “and / or” as used in this application refers to any combination of one or more of the listed items, and all possible combinations thereof.
[0026] Example 1: A spectral processing system, reference Figure 1 and Figure 2 It includes an optical front end, a dispersive element 6, a relay lens group, a beam splitter 7, a liquid crystal spatial light modulator 8, and a spectral detector 9 arranged sequentially. The back focal plane of the optical front end, the liquid crystal spatial light modulator 8, and the spectral detector 9 are all disposed on the corresponding focal plane of the relay lens group.
[0027] The optical front end is used to receive input light and collimate and shape its spot. Specifically, the optical front end includes an optical port 1, a collimator 2, and a front cylindrical lens 3. The optical port 1 serves as the interface between the system and the external optical path and can take various forms.
[0028] For example, the optical port 1 may be a fiber array, which includes at least one input port and multiple output ports for carrying signals in the optical communication band.
[0029] For example, the optical port 1 can also be a waveguide grating coupler array, which is directly integrated on the corresponding photonic chip.
[0030] Collimator 2 is positioned after optical port 1 to collimate the outgoing diverging beam and reduce its divergence angle. Front cylindrical lens 3 is used to pre-shape the beam in the non-dispersive direction (i.e., the direction perpendicular to the dispersion direction y) or the dispersive direction to obtain an elliptical spot suitable for the dispersion of the subsequent grating.
[0031] The dispersive element 6 is located downstream of the optical path of the optical front end and is used to disperse the input light into beams of different wavelengths in the dispersive direction (y-direction). The dispersive element 6 is the core beam-splitting component of the system.
[0032] For example, the dispersive element 6 is a reflective prism grating, which combines the features of a prism and a grating, enabling high-efficiency dispersion and reducing the coupling effect caused by conical diffraction. The reflective prism grating is configured to operate under Littoral angle conditions to obtain maximum diffraction efficiency.
[0033] For example, the dispersive element 6 can also be a volume holographic grating (VHG) with high diffraction efficiency and angle selectivity.
[0034] For example, the dispersive element 6 may also be an etched grating, such as an echelle grating, for achieving high spectral resolution.
[0035] The relay lens group is used to focus the light spot in the dispersion direction and the port direction. Specifically, the relay lens group includes a dispersion direction cylindrical lens 4 and a port direction cylindrical lens 5.
[0036] Reference Figure 3 The focal length of the dispersive cylindrical lens 4 is f1. On the dispersive plane (yz plane), the back focal plane of the optical front end, the dispersive element 6, the polarization-independent liquid crystal spatial light modulator 8, and the spectral detector 9 are all positioned on the focal plane of the dispersive cylindrical lens 4. The angular dispersion at the dispersive element 6 is converted into spatial position separation on the focal plane of the liquid crystal spatial light modulator 8, thereby achieving precise wavelength-to-position mapping.
[0037] Reference Figure 4 The port-direction cylindrical lens 5 is positioned between the dispersive cylindrical lens 4 and the dispersive element 6, and its focal length f2 is approximately twice that of f1. In the port direction (xz plane), the back focal plane of the optical front end, the polarization-independent liquid crystal spatial light modulator 8, and the spectral detector 9 are located on the focal plane of the port-direction cylindrical lens 5.
[0038] This configuration constitutes a 2f optical system, capable of converting the position information of the input port into angular information on the liquid crystal spatial light modulator 8, and vice versa. This allows the liquid crystal spatial light modulator 8 to precisely guide the light beam to different output ports by finely adjusting the reflection angle, thus realizing the function of a wavelength selective switch (WSS).
[0039] Beam splitter 7 is located downstream of the optical path of the relay lens group, splitting the light beam from the dispersive element 6 into a first beam and a second beam. Beam splitter 7 is typically a cube beam splitter (BS cube) or a plate beam splitter.
[0040] For example, the beam splitting ratio can be set to 9:1 or 8:2, meaning that most of the light is used for shaping the output and a small portion is used for monitoring. The first beam is transmitted or reflected and then directed to the liquid crystal spatial light modulator 8, and the second beam is reflected or transmitted and then directed to the spectral detector 9.
[0041] Furthermore, the liquid crystal spatial light modulator 8 is disposed on the optical path of the first beam and has polarization-independent characteristics, so as to perform phase and / or amplitude modulation processing on different wavelength components of the first beam, and reflect the processed beam along the original optical path to output it through the optical port 1.
[0042] Traditional LCoS are sensitive to polarization and can typically only modulate linearly polarized light in a specific direction, thus requiring complex polarization diversity optical paths. This application achieves uniform modulation of arbitrary polarization states by integrating a metasurface inside the LCoS (see Embodiment 4), greatly simplifying the optical path structure.
[0043] Furthermore, a spectral detector 9 is positioned in the optical path of the second beam to receive the second beam and detect its spectral power distribution to obtain spectral information. The spectral detector 9 can be a linear InGaAs detector or a CCD / CMOS detector, with its pixel arrangement direction aligned with the dispersion direction.
[0044] The liquid crystal spatial light modulator 8 and the spectral detector 9 are arranged conjugately with respect to the beam splitter 7. That is, their optical path lengths after the beam splitter 7 are strictly equal. Therefore, the light spot, after being transformed by the dispersive element 6 and the relay lens group, has the same shape, size, and positional distribution on the surface of the liquid crystal spatial light modulator 8 and the photosensitive surface of the spectral detector 9. This conjugate design ensures that the measured spectrum is the same as the spectral distribution, meaning that the spectral distribution detected by the spectral detector 9 accurately reflects the spectral distribution to be processed on the liquid crystal spatial light modulator 8, reducing spectral calibration errors caused by differences in the optical path.
[0045] Example 2: A spectral processing system, which differs from Embodiment 1 in that this embodiment is a further extension of Embodiment 1.
[0046] Reference Figure 5 The optical ports 1 are provided in multiple sets, and the photosensitive surfaces of the liquid crystal spatial light modulator 8 and the spectral detector 9 are divided into multiple regions, each corresponding to one of the multiple sets of optical ports 1. The number of optical ports 1 can be specifically set according to the actual situation, such as two sets, three sets, four sets or even more.
[0047] For example, optical port 1 includes two independent fiber arrays, namely a first port group (Group I) and a second port group (Group II), which are vertically arranged in the port direction (x direction). Correspondingly, the photosensitive surfaces of the liquid crystal spatial light modulator 8 and the spectral detector 9 are divided into two regions, which are arranged one-to-one with the two groups of optical ports 1.
[0048] For example, the photosensitive surface of the liquid crystal spatial light modulator 8 is divided into an upper half and a lower half, with the upper half corresponding to Group I and the lower half corresponding to Group II. The same applies to the spectral detector 9, which will not be elaborated further here.
[0049] Beam splitter 7 simultaneously projects beams from multiple optical ports 1 onto corresponding regions of the liquid crystal spatial light modulator 8 and the spectral detector 9. Since the port direction cylindrical lenses 5 form a 2f system in the port direction, port beams input at different heights (x-coordinate) will be imaged at different height regions of the LCoS and the detector after passing through the system, without interfering with each other.
[0050] This twin-structure design enables simultaneous detection and shaping of multiple independent spectra. For example, it can process multiple sets of optical communication signals simultaneously, or perform spectral analysis on multiple different physical experimental objects at the same time, greatly improving the utilization and integration of the equipment.
[0051] Example 3: A spectral processing system, which differs from Embodiment 2 in that, based on the multi-port structure in Embodiment 2, this embodiment constructs a processing system with closed-loop feedback function.
[0052] Reference Figure 6 Continuing with the example of Embodiment 2, optical port 1 is provided with two groups, including a first port group and a second port group. Further, the output port of the first port group is connected to the input port of the second port group via optical fiber coupling.
[0053] The optical path operation process is as follows: T1. The optical signal to be processed is input from the first port group.
[0054] T2. The optical signal passes through the system and undergoes its first shaping in the first region of the liquid crystal spatial light modulator 8.
[0055] T3. The shaped beam is reflected back to the output port of the first port group.
[0056] T4. The beam is further transmitted to the input port of the second port group through an external jumper or internal optical path.
[0057] T5. The beam re-enters the system and is projected onto the second region of the spectral detector 9.
[0058] The second region of the spectral detector 9 detects the shaped spectral data.
[0059] This loopback structure allows the system to simultaneously detect both input and output spectra. Users can dynamically adjust the phase pattern of the liquid crystal spatial light modulator based on real-time feedback from the output spectrum to compensate for environmental fluctuations or device drift.
[0060] Example 4: See Figure 7 This embodiment describes in detail the specific structure of the polarization-independent liquid crystal spatial light modulator 8 applied in embodiments 1-3. The liquid crystal spatial light modulator 8 includes a substrate layer, a liquid crystal phase modulation layer, and a metasurface layer stacked together.
[0061] The substrate layer integrates driving circuitry to provide independent voltage control signals for each pixel. The liquid crystal phase modulation layer contains liquid crystal molecules that can be deflected by voltage control. When a voltage is applied, the director of the liquid crystal molecules deflects, thereby changing the effective refractive index in which light waves propagate and producing a phase delay.
[0062] A metasurface layer is embedded between the substrate layer and the liquid crystal phase modulation layer, reflecting incident light and rotating its polarization direction. The specific operating principle is as follows: The incident light first passes through the liquid crystal phase modulation layer. Regardless of its polarization direction, the light wave is reflected by the underlying metasurface layer. This metasurface acts as a nanoscale half-wave plate, efficiently rotating the linear polarization direction of the incident light by 90° (e.g., converting 0° polarization to 90° polarization, and vice versa). The reflected and polarized light wave then passes through the liquid crystal phase modulation layer again before exiting.
[0063] For incident polarized light (0°) parallel to the orientation of the liquid crystal (LC): it is phase modulated when it passes through the LC for the first time, and its polarization becomes orthogonal (90°) after reflection by the metasurface. When it passes through the LC layer for the second time, it is not modulated because its polarization direction is perpendicular to the LC orientation.
[0064] For incident polarized light perpendicular to the LC orientation (90°): it is not modulated when it passes through the LC for the first time, and its polarization becomes parallel (0°) after reflection by the metasurface. It is phase modulated when it passes through the LC layer for the second time.
[0065] Therefore, both orthogonal linearly polarized lights underwent the same phase modulation, achieving polarization-independent operation.
[0066] This working principle can be rigorously described and proven mathematically using the Jones Matrix. Let the phase modulation matrix of the liquid crystal phase modulation layer be... ,in It is a dynamic phase delay controlled by voltage. The metasurface acts as an ideal, broadband optical half-wave plate, whose matrix can be represented as... To ensure polarization rotation, the principal axis of the metasurface nanoantenna is at a 45° angle to the orientation of the liquid crystal molecules; therefore, a 45° rotation matrix needs to be introduced. and its inverse matrix To transform the coordinate system.
[0067] The entire optical transmission process (two-way) of the device can be represented as the following matrix multiplication: in, = , , Substituting the above matrix and calculating, we get: The final transmission matrix T indicates that the device applies a dynamic phase delay φ to the overall effect of the light wave. This phase modulation is not only independent of the polarization state of the incident light, but the device also performs a polarization exchange function, that is, the two polarization components of the outgoing light are exchanged relative to the incident light.
[0068] The metasurface unit comprises a reflective layer, a dielectric substrate, and a dielectric pillar arranged sequentially.
[0069] A reflective layer is disposed beneath the dielectric substrate to reflect the light beam. The material of the reflective layer can be specifically configured according to the actual situation, including but not limited to gold, silver, aluminum, platinum, chromium, silicon, and copper. For example, the reflective layer is configured as an aluminum layer.
[0070] The material of the dielectric substrate can be specifically set according to the actual situation, including but not limited to silicon nitride, titanium dioxide, aluminum oxide, or silicon dioxide. For example, the dielectric substrate is a silicon nitride layer.
[0071] The material of the dielectric pillar can be specifically set according to the actual situation, including but not limited to silicon and titanium dioxide. For example, the material of the dielectric pillar is set to silicon. The shape of the dielectric pillar can be set as a polygonal prism, an elliptical cylinder, or a cube, and is not specifically limited here.
[0072] Reference Figure 7 For example, the metasurface layer unit has a period of 1000 nm, and the length, width and height of the dielectric pillars are 880 nm, 220 nm and 330 nm, respectively.
[0073] The primary function of the metasurface layer is to convert incident linearly polarized light (0°) into orthogonally polarized light (90°). To demonstrate the device's functionality, the polarization conversion ratio (PCR) is used to quantify its performance, and its expression is as follows: in, This represents the energy of orthogonally polarized light in the reflected light. This represents the energy of the original polarized light in the reflected light.
[0074] Combination Figure 8 , Figure 8The PCR performance of the metasurface layer in the working wavelength range (1525nm-1570nm) was demonstrated. As shown in the figure, the PCR performance of the device in the working range is greater than 99%, indicating that the device has excellent polarization conversion capability. Therefore, the polarization-independent LCoS chip constructed by this device has excellent polarization independence capability.
[0075] Example 5: A spectral processing method employing the aforementioned spectral processing system. The method includes the following steps: S100: After the input light is collimated and shaped by the optical front end, it is spatially dispersed according to wavelength by the dispersive element.
[0076] S200: After being focused and transformed by the relay lens group, the expanded beam is split by the beam splitter into a shaping beam that is transmitted to the liquid crystal spatial light modulator and a detection beam that is transmitted to the spectral detector.
[0077] The shaping beam corresponds to the first beam mentioned above, and the detection beam corresponds to the second beam mentioned above.
[0078] The S300 spectrometer receives the optical signal from the probe beam, records the optical power at each pixel position, and calculates the input spectrum based on the correspondence between pixel position and wavelength.
[0079] In step S300, the calculated input spectrum further includes a spectral restoration step, which specifically includes: Constructing a degradation model: in, It is the observed light power at each pixel location. It is the optical power of the input light at each wavelength. It is a degradation function that is related to pixel spatial location and wavelength. The noise level is denoted by N, where N is the number of pixels in the dispersion direction of the spectral detector. This represents the spatial location of each pixel on the spectral detector. The wavelength; The measured optical power at each pixel location The optical power of each wavelength of the input light is obtained by deconvolution. To restore the input spectrum and improve spectral resolution.
[0080] It should be noted that spectral restoration algorithms include Wiener deconvolution, blind deconvolution, and convolutional neural networks (CNN).
[0081] S400: The shaping beam is incident on a polarization-independent liquid crystal spatial light modulator. The liquid crystal spatial light modulator, according to the preset shaping requirements, changes the refractive index of the liquid crystal by adjusting the voltage of each pixel, performs phase delay and / or attenuation on light of different wavelengths in the shaping beam, and controls the direction of the reflected light to couple it to the selected output port.
[0082] In step S400, the polarization-independent processing includes: The incident light passes through the liquid crystal phase modulation layer for the first time and is subjected to the first phase modulation. When light waves reach the metasurface layer, the metasurface layer rotates the polarization state of the incident light by 90 degrees and reflects it. The reflected light passes through the liquid crystal phase modulation layer a second time and is modulated by a second phase. By rotating the polarization, the two orthogonal polarization components of the incident light undergo complementary modulation paths, thus achieving a total phase modulation that is independent of the polarization state of the incident light.
[0083] Example 6: A computer-readable medium having a computer program stored thereon. When the program is executed by a processor, it implements the spectral processing method as described in Example 5.
[0084] The computer program includes the following functional modules: Spectral acquisition module: controls the spectral detector 9 for exposure and data reading.
[0085] Spectral restoration module: Executes the deconvolution algorithm to convert the original measurement data y(v) into a high-resolution spectrum x(w).
[0086] Driven calculation module: Calculates the phase hologram required for LCoS based on the target spectral shape set by the user and the currently measured input spectrum.
[0087] LCoS loading module: Loads the calculated holographic voltage signal onto the driving circuit of the liquid crystal spatial light modulator 8 to complete spectral shaping.
[0088] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be covered within the scope of protection of this application.
Claims
1. A spectral processing system, characterized in that, It includes an optical front end, a relay lens group, a dispersive element and a beam splitter arranged in sequence, wherein the beam splitter splits the light beam from the dispersive element into a first beam and a second beam; The system also includes: A liquid crystal spatial light modulator is disposed in the optical path of the first beam and has polarization-independent characteristics. It is used to perform phase and / or amplitude modulation processing on different wavelength components of the first beam and to reflect the processed beam along the original optical path for output via the optical front end. A spectral detector is placed in the optical path of the second beam to receive the second beam and detect its spectral power distribution to obtain spectral information.
2. The spectral processing system according to claim 1, characterized in that, The optical front end includes an optical port, a collimator, and a front cylindrical lens arranged sequentially. The optical ports are provided in multiple sets, and the photosensitive surfaces of the liquid crystal spatial light modulator and the spectral detector are divided into multiple regions, which correspond one-to-one with the multiple sets of optical ports. The beam splitter simultaneously projects beams from multiple optical ports onto corresponding areas of the liquid crystal spatial light modulator and the spectral detector, enabling simultaneous detection and shaping of multiple independent spectra.
3. The spectral processing system according to claim 2, characterized in that, The optical ports are provided in two groups, including a first port group and a second port group; The output port of the first port group is connected to the input port of the second port group via optical fiber coupling, so that the output light of the first port group after being shaped by the liquid crystal spatial light modulator is input into the system again for secondary detection or secondary shaping.
4. The spectral processing system according to any one of claims 1-3, characterized in that, The liquid crystal spatial light modulator includes: basal layer; A liquid crystal phase modulation layer comprising liquid crystal molecules that can be deflected by voltage control; A metasurface layer, which is embedded between the substrate layer and the liquid crystal phase modulation layer, is used to reflect incident light and rotate its polarization direction; The metasurface layer includes multiple metasurface units arranged in an array, which are used to rotate the incident linearly polarized light by 90 degrees and reflect it, so that the two orthogonal polarization components undergo the same phase modulation.
5. The spectral processing system according to claim 4, characterized in that, The metasurface unit includes a reflective layer, a dielectric substrate, and a dielectric pillar arranged sequentially.
6. The spectral processing system according to claim 1, characterized in that, The relay lens group includes: The dispersive directional cylindrical lens has its back focal plane of the optical front end, the dispersive element, the liquid crystal spatial light modulator, and the spectral detector all disposed on the focal plane of the dispersive directional cylindrical lens. A port-direction column lens is disposed between the dispersive column lens and the dispersive element, and its focal length is approximately twice that of the dispersive column lens. The back focal plane of the optical front end, the liquid crystal spatial light modulator, and the spectral detector are located on the focal plane of the port-direction column lens. The liquid crystal spatial light modulator and the spectral detector are arranged conjugately relative to the beam splitter, and their optical path lengths after the beam splitter are equal, so that the light spot shapes received by both are the same.
7. A spectral processing method, characterized in that, The method using the spectral processing system according to any one of claims 1-6 includes the following steps: S100: After the input light is collimated and shaped by the optical front end, it is spatially dispersed according to wavelength by the dispersive element; S200: After the expanded input light is focused and transformed by the relay lens group, it is split by the beam splitter into a shaped beam that is transmitted to the liquid crystal spatial light modulator and a probe beam that is transmitted to the spectral detector. S300: The spectral detector receives the optical signal of the probe beam, records the optical power at each pixel position, and calculates the input spectrum based on the correspondence between pixel position and wavelength. S400: The shaping beam is incident on a polarization-independent liquid crystal spatial light modulator. The liquid crystal spatial light modulator, according to the preset shaping requirements, changes the refractive index of the liquid crystal by adjusting the voltage of each pixel, performs phase delay and / or attenuation on light of different wavelengths in the shaping beam, and controls the direction of the reflected light to couple it to the selected output port.
8. The spectral processing method according to claim 7, characterized in that, In step S300, the calculated input spectrum further includes a spectral restoration step: Constructing a degradation model: ; in, It is the observed light power at each pixel location. It is the optical power of the input light at each wavelength. It is a degradation function that is related to pixel spatial location and wavelength. The noise level is denoted by N, where N is the number of pixels in the dispersion direction of the spectral detector. This represents the spatial location of each pixel on the spectral detector. The wavelength; The measured optical power at each pixel location The optical power of each wavelength of the input light is obtained by deconvolution. To restore the input spectrum and improve spectral resolution.
9. The spectral processing method according to claim 7, characterized in that, In step S400, the polarization-independent processing includes: The incident light passes through the liquid crystal phase modulation layer for the first time and is subjected to the first phase modulation. When light waves reach the metasurface layer, the metasurface layer rotates the polarization state of the incident light by 90 degrees and reflects it. The reflected light passes through the liquid crystal phase modulation layer a second time and is modulated by a second phase. By rotating the polarization, the two orthogonal polarization components of the incident light undergo complementary modulation paths, thus achieving a total phase modulation that is independent of the polarization state of the incident light.
10. A computer-readable medium having a computer program stored thereon, characterized in that, When the program is executed, it implements the method as described in claims 7-9.