A phase amplitude decoupled modulator for complex amplitude modulation

Abstract

The application discloses a phase-amplitude decoupling modulator for complex amplitude modulation, which comprises at least a first modulation layer, a second modulation layer and a phase-amplitude decoupling modulator, wherein the phase-amplitude decoupling modulator comprises a controller, a first excitation module and a second excitation module; the first excitation module inputs independent excitation signals to the first modulation pixel unit; and the second excitation module inputs independent excitation signals to the second modulation pixel unit. The application breaks through the shackles of low amplitude-phase modulation level, mutual restraint of phase-amplitude modulation effect, complex preparation process and the like, and can realize independent and multi-order amplitude modulation and phase modulation for complex amplitude complete information reconstruction, so that the resolution, amplitude distribution uniformity, precision, signal-to-noise ratio and other performances are improved, and the dynamic switching of images and the improvement of reconstructed image quality are completed.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical technology, in particular, the present application relates to a kind of phase amplitude decoupling modulator for complex amplitude modulation. BACKGROUND

[0002] Complex amplitude modulation technology records and reconstructs the entire wave information of a target and object by modulating the complex amplitude information of light wave, and has important application prospects in the field of holography, spatial light modulator, etc., has been widely used in 3D display, interferometry, military reconnaissance surveillance, information storage, medical detection and many other national defense and real life.

[0003] Static complex amplitude modulation technology is the existing more common complex amplitude modulation technology, and its modulation effect is fixed when the structure of the modulation device is generated, and cannot be adjusted, only a certain reconstruction image can be generated. Dynamic complex amplitude modulation can dynamically adjust the light wave information without changing the structure of the device, and output a sequence of dynamic images. In the prior art, dynamic complex amplitude modulation is based on signal excitation on the structure of the modulation unit, so that the optical properties change, thereby modulating the amplitude and phase values of the light wave.

[0004] Because the amplitude modulation and phase modulation effects are mutually restrained, a dynamic complex amplitude modulation unit (single-factor dynamic modulation) modulated by a signal excitation cannot obtain the required amplitude and phase combination, i.e. cannot obtain the required complex amplitude value.

[0005] Optimizing the structure of the modulation unit to achieve dynamic modulation is the focus of researchers. For example, increasing the size of the dynamic complex amplitude modulation unit can achieve pure amplitude dynamic modulation (the amplitude modulation amount changes with the excitation signal strength, and the phase shift amount remains unchanged), or pure phase dynamic modulation (the phase modulation amount changes with the excitation signal strength, and the amplitude attenuation amount remains unchanged). To some extent, the amplitude and phase are independently controlled, the multi-order amplitude and phase changes of the unit structure are realized, and the complex amplitude value of the light wave is more finely modulated. However, the increase in the size of the unit reduces the resolution of the entire device, which is contrary to the trend of high resolution and high precision of complex amplitude modulation technology today.

[0006] After the first modulation layer modulates the phase of the light wave pixel by pixel, the transmission direction of the light wave modulated by different units changes, and the problem of light information crosstalk between the two modulation layers inevitably occurs. In order to solve this problem, the prior art limits the incident light to be parallel light, and the first modulation is pure amplitude modulation, which only changes the intensity of the light, but not the phase of the light, i.e. the transmission direction of the light beam does not change after pure amplitude modulation. After the light beam is modulated by the amplitude modulation device, the outgoing light is still parallel light. However, the pure amplitude modulation unit design is complex, the unit size is large, and the manufacturing cost is high, which greatly reduces the feasibility of this scheme. SUMMARY

[0007] The application aims to provide a phase-amplitude decoupling modulator for complex amplitude modulation, which does not rely on the dynamic modulation effect of the modulation unit itself, adopts two modulation units, combines two independent signal excitations which are easy to control, and greatly improves the controllability of complex amplitude modulation through second-order dynamic control.

[0008] Further, the two-stage control effect of complex amplitude inevitably influences each other. In the initial scheme of the application, high-precision modulation cannot be achieved through conventional pure amplitude modulation followed by pure phase modulation or pure phase modulation followed by pure amplitude modulation. After in-depth research by the team, it is found that the modulation amount of the pure amplitude dynamic modulation unit on the phase will also change under different signal intensity excitations, and similarly, the modulation amount of the pure phase dynamic modulation unit on the amplitude will also change under different signal intensity excitations. The mutual restraint between amplitude modulation and phase modulation is an important factor leading to the imperfection of the initial scheme of the application. So far, no existing technology has disclosed the above factors and related factors, and no existing technology has related the above factors and related factors to complex amplitude modulation.

[0009] Specifically, the application adopts the following technical scheme: the method comprises:

[0010] The spatial light modulator at least comprises a first modulation layer and a second modulation layer; the first modulation layer comprises one or more first modulation pixel units, and the second modulation layer comprises one or more second modulation pixel units; the light beam modulated by the first modulation pixel unit is projected to the unique second modulation pixel unit for secondary modulation;

[0011] And the phase-amplitude decoupling modulator comprises a controller, a first excitation module and a second excitation module; the first excitation module inputs an excitation signal to the first modulation pixel unit to change the optical property thereof; the second excitation module inputs an excitation signal to the second modulation pixel unit to change the optical property thereof; the controller controls the excitation signals of the first excitation module and the second excitation module, specifically:

[0012] According to the complex amplitude information A n (t, λ) and P n (t, λ) of the target light wave at the nth pixel unit, and the initial complex amplitude information and The phase modulation change amount and the amplitude modulation change amount of the nth pixel unit are obtained, the amplitude attenuation ratio and the phase shift amount of the nth first modulation pixel unit and the nth second modulation pixel unit are decoupled, and thus the excitation signals applied to the nth first modulation pixel unit and the nth second modulation pixel unit are obtained; wherein t represents the time t, and λ represents the wavelength of the incident light.

[0013] It should be noted that the optical properties of a modulation pixel unit refer to the various properties exhibited by the modulation pixel unit in terms of absorption, reflection, refraction, scattering, and diffraction of light. Under the excitation of an excitation signal (e.g., a phase change material under the excitation of an electrical signal), its optical properties change, altering its various properties in terms of absorption, reflection, refraction, scattering, and diffraction of light, and consequently changing the amplitude attenuation ratio and phase shift. In other words, after an excitation signal, the optical properties of a modulation pixel unit, such as its refractive index and extinction coefficient, change, and the corresponding amplitude attenuation ratio and phase shift also change (e.g., ...). Figure 4 Those skilled in the art can deduce the required excitation signal from the required amplitude attenuation ratio and phase shift by reverse calculation, thereby achieving optical modulation. Therefore, materials capable of optical property modulation, such as phase change materials and liquid crystal materials, can be used as the modulation pixel unit of this application.

[0014] The phase change material can be: GeSbTe, GeSeSbTe, or VO2.

[0015] The liquid crystal material can be: biphenyl liquid crystal, phenylcyclohexane liquid crystal, or ester liquid crystal.

[0016] In some preferred embodiments, the first modulation pixel unit directly adopts an amplitude modulation unit, and the second modulation unit directly adopts a phase modulation unit; or the first modulation pixel unit directly adopts a phase modulation unit, and the second modulation unit directly adopts an amplitude modulation unit. The aforementioned amplitude modulation unit is a pixel modulation unit that focuses on amplitude modulation, and the phase modulation unit is a pixel modulation unit that focuses on phase modulation. For example, the amplitude modulation unit used is one in which, under the control of electrical excitation, the modulation of the light wave amplitude is uniform and multi-stage within the range of 0-1, while its change in the light wave phase is within ±π / 5; the phase modulation unit is one in which, under the control of electrical excitation, the modulation of the light wave phase is uniform and multi-stage within the range of 0-2π, while its change in the light wave amplitude is stable, with fluctuation values ​​within 10%.

[0017] The principle of decoupling is as follows: the phase information of the light wave in the nth pixel unit is simultaneously modulated by the nth first modulation pixel unit and by the nth second modulation pixel unit. The phase difference between the target light wave and the incident light wave in the nth pixel unit is equal to the sum of the phase modulation amount of the nth first modulation pixel unit and the phase modulation amount of the nth second modulation pixel unit. The amplitude attenuation ratio between the target light wave and the incident light wave in the nth pixel modulation unit is simultaneously modulated by the nth first modulation pixel unit and the nth second modulation pixel unit. The amplitude attenuation ratio between the target light wave and the incident light wave is equal to the product of the amplitude modulation amount of the nth first modulation pixel unit and the amplitude modulation amount of the nth second modulation pixel unit.

[0018] Further, the excitation signal is an electrical excitation signal, an optical excitation signal, a stress excitation signal, a thermal excitation signal, or other excitation signals.

[0019] Further, the first modulation pixel units and the second modulation pixel units are arrayed respectively to form the first modulation layer and the second modulation layer; and the first modulation pixel units and the second modulation pixel units correspond to each other one by one.

[0020] Further, the first excitation module and the second excitation module comprise electrode units, and the electrode units correspond to the first modulation layer pixel units and the second modulation layer pixel units one by one.

[0021] Further, the first modulation layer and the second modulation layer are seamlessly spliced.

[0022] The present application has the advantages that: the present application optimizes the modulation effects of the two-stage modulation by setting a phase-amplitude decoupling modulator. The two-stage dynamic complex amplitude modulation is an ideal technical path with the best performance in all aspects and greatly simplified structure, and simultaneously realizes the functions of dynamic modulation of an image, two-stage (Two-stage) independent modulation of phase and amplitude, and the like, and can obtain high-quality wavefront reconstruction of a real holographic dynamic image. The present application breaks through the shackles of low modulation stage number of amplitude and phase, mutual interference, complex preparation process, and the like, and can realize independent and multi-level amplitude modulation and phase modulation, complete information reconstruction of complex amplitude, time-space separation of the amplitude and phase modulation processes, and the like, so as to improve the performance of resolution, amplitude distribution uniformity, precision, signal-to-noise ratio, and the like, and to complete dynamic switching of an image and improve the quality of a reconstructed image. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a first modulation pixel unit in Example 1 using a digital metasurface structure based on a phase change material, different crystal state / amorphous state combinations;

[0024] Figure 2 is Figure 1 is a complex amplitude modulation condition of the first modulation pixel unit in Example 1 under different equivalent electrical excitation intensities, Figure 2 A is the adjustment amount of amplitude with different electrical excitation intensities, Figure 2 B is the adjustment amount of phase with different electrical excitation intensities;

[0025] Figure 3 is a second modulation pixel unit in Example 1 using a digital metasurface structure based on a phase change material, different crystal state / amorphous state combinations;

[0026] Figure 4 is Figure 3 is a complex amplitude modulation condition of the second modulation pixel unit in Example 1 under different equivalent electrical excitation intensities,Figure 4 A is the adjustment amount of the phase with the different electric excitation intensity, Figure 4 B is the adjustment amount of the amplitude with the different electric excitation intensity;

[0027] Figure 5 is the complex amplitude modulation device structure in which each modulation pixel unit in Example 2 is controlled by an independent excitation module;

[0028] Figure 6 is the unit structure adopted by the first modulation pixel unit and the second modulation pixel unit in Example 2;

[0029] Figure 7 is the simulation structure adopted in Examples 2 and 3;

[0030] Figure 8 is the simulation result of two-stage complex amplitude modulation after decoupling algorithm is adopted in Example 2, Figure 8 A is the amplitude value distribution diagram of the light wave output plane, Figure 8 B is the phase value distribution diagram of the light wave output plane;

[0031] Figure 9 is the simulation result of two-stage complex amplitude modulation without decoupling algorithm in Example 2, Figure 9 A is the amplitude value distribution diagram of the light wave output plane, Figure 9 B is the phase value distribution diagram of the light wave output plane;

[0032] Figure 10 is the unit structure adopted in Example 3;

[0033] Figure 11 is the simulation result of two-stage complex amplitude modulation after decoupling algorithm is adopted in Example 3, Figure 11 A is the amplitude value distribution diagram of the light wave output plane, Figure 11 B is the phase value distribution diagram of the light wave output plane;

[0034] Figure 12 is the simulation result of two-stage complex amplitude modulation without decoupling algorithm in Example 3, Figure 12 A is the amplitude value distribution diagram of the light wave output plane, Figure 12 B is the phase value distribution diagram of the light wave output plane; DETAILED DESCRIPTION

[0035] Example 1

[0036] This embodiment takes the two-stage modulation pixel units before and after as an example to illustrate the unique advantages of two-stage modulation in improving the precision of complex amplitude dynamic modulation.

[0037] Figure 1is the first modulation pixel unit of the present embodiment, which adopts a digital metasurface unit structure based on phase change material. The substrate is a 1600 nm x 1600 nm Si material, on which four 800 nm high GSST (Ge2Sb2Se4Te) cylinders of different sizes are placed, with radii of d1 = 425 nm, d2 = 220 nm, d3 = 205 nm, and d4 = 230 nm, respectively. Each GSST cylinder is provided with an electric excitation source, and the crystalline / amorphous state of each GSST material can be independently controlled. The communication wavelength tested is 1550 nm. Under different crystalline / amorphous state combinations of the four GSST materials, the modulation amounts of the amplitude modulation digital metasurface unit (the first modulation pixel unit) on the amplitude and phase of the light wave in the region are as follows Figure 2 A and 4B, and the data is shown in Table 2 (WXYZ represents the GSST cylinder with a diameter of D1, D2, D3, and D4, respectively):

[0038] Table 1: Modulation amounts of the amplitude modulation digital metasurface unit (the first modulation pixel unit) on the amplitude and phase of the light wave in Example 1

[0039]

[0040] Figure 3 is the second modulation pixel unit made in the present embodiment, which adopts a digital metasurface structure based on phase change material. The substrate is a 1600 nm x 1600 nm Si material, on which four 800 nm high GSST (Ge2Sb2Se4Te) cylinders of different sizes are placed, with radii of D1 = 470 nm, D2 = 435 nm, D3 = 410 nm, and D4 = 365 nm, respectively. Each GSST cylinder is provided with an electric excitation source, and the crystalline / amorphous state of each GSST material can be independently controlled. The communication wavelength tested is 1550 nm. Under different crystalline / amorphous state combinations of the four GSST materials, the modulation amounts of the phase modulation digital metasurface unit (the second modulation pixel unit) on the amplitude and phase of the light wave in the region are as follows Figure 4 A and 4B, and the data is shown in Table 2 (WXYZ represents the GSST cylinder with a diameter of D1, D2, D3, and D4, respectively):

[0041] Table 2: Modulation amounts of the phase modulation digital metasurface unit (the second modulation pixel unit) on the amplitude and phase of the light wave in Example 1

[0042]

[0043] The single first modulation pixel unit has eight different amplitude modulation amounts and three different phase modulation amounts, and a total of eight different complex amplitude values; the single second modulation pixel unit has eight different complex amplitude modulation amounts with different amplitude and phase changes. After combination, the range of the modulated complex amplitude modulation is expanded to 8x8. Assuming that the incident light is a plane wave perpendicular to the device, with a phase of 0 and an amplitude of 1, all the amplitude values of the light waves obtained by all the different crystal / amorphous state combinations of the first modulation pixel unit and the second modulation pixel unit are shown in Table 3:

[0044] Table 3: All light wave amplitude modulation values obtained by different crystal / amorphous state combinations

[0045] Amplitude value BCD / A BD / AC CD / AB B / ACD / ABCD AB / CD AC / BD A / BCD XYZ / W 0.012 0.016 0.0096 0.0088 0.0088 0.0076 0.0008 0.0072 WXY / Z 0.108 0.144 0.0864 0.0792 0.0792 0.0684 0.0072 0.0648 WX / YZ 0.132 0.176 0.1056 0.0968 0.0968 0.0836 0.0088 0.0792 W / XYZ 0.216 0.288 0.1728 0.1584 0.1584 0.1368 0.0144 0.1296 / WXYZ 0.312 0.416 0.2496 0.2288 0.2288 0.1976 0.0208 0.1872 Z / WXY 0.384 0.512 0.3072 0.2816 0.2816 0.2432 0.0256 0.2304 Y / WXZ 0.432 0.576 0.3456 0.3168 0.3168 0.2736 0.0288 0.2592 YZ / WX 0.492 0.656 0.3936 0.3608 0.3608 0.3116 0.0328 0.2952

[0046] All the phase values of the light waves obtained by all the different crystal / amorphous state combinations of the amplitude dynamic modulation unit and the phase dynamic modulation unit are shown in Table 4 and Table 3:

[0047] Table 4: All light wave phase modulation values obtained by different crystal / amorphous state combinations

[0048]

[0049] As can be seen from the above, by changing the excitation mode of the first modulation pixel unit and the second modulation pixel unit and selecting different crystal / amorphous state combinations, the eight amplitude and phase combinations of the original one-level modulation can be expanded to 64 amplitude and phase modulation combinations, greatly improving the precision of the complex amplitude modulation of the light wave.

[0050] Those skilled in the art should know that the present embodiment can be replaced by other PCM microstructures, and the high-precision technical effects of the present embodiment can also be achieved, such as rod-shaped, V-shaped, cross-shaped, C-shaped structures, etc., with a thickness in the range of 50-600 nm. Arranging and combining the PCM microstructures, and each microstructure having a separate electrical excitation source, can realize the mutual transformation between the crystal state and the amorphous state of each microstructure, so that the optical properties (such as refractive index, extinction coefficient, etc.) of the first modulation pixel unit change, thereby realizing the changes in the phase modulation amount and the amplitude modulation amount of the entire digital metasurface unit (modulation pixel unit). In addition, several PCM microstructures with different shapes can be placed on a substrate to form a digital metasurface unit, and the electrical excitation of each microstructure can produce changes in optical properties under different phase state combinations, thereby realizing changes in the amplitude attenuation ratio and the phase shift amount of the digital metasurface unit, and encoding each change value can achieve nearly continuous multi-order phase changes in the full range of [0, 2π] and nearly continuous multi-order amplitude changes in the full range of [0, 1].

[0051] In this application, each modulation pixel unit on the first modulation layer and the second modulation layer is controlled by an independent signal excitation source, and the units do not interfere with each other. Those skilled in the art can foresee based on this embodiment that the two-level modulation based on the first modulation layer and the second modulation layer can also greatly improve the modulation accuracy.

[0052] Example 2

[0053] like Figure 5 As shown, this embodiment provides a complex amplitude dynamic modulator, including a first modulation layer and a second modulation layer. The first modulation layer has first modulation pixel units M1 to M3, each of which is excited by an independent first excitation module. The second modulation layer has second modulation pixel units N1 to N3, each of which is excited by an independent second excitation module. The first and second modulation pixel units each form an array, and the first and second modulation layer pixel units are seamlessly spliced ​​together. The controller controls the intensity of the excitation signals output by the first and second excitation modules.

[0054] When the local light wave is modulated once by the first modulation pixel unit M1 of the spatial light modulator, the controller controls the first excitation module to input the excitation signal U to the first modulation pixel unit M1. M1 The optical properties of the first pixel modulation unit are changed; the light wave after being modulated once is modulated a second time through the second modulation pixel unit N1, and the controller controls the excitation intensity U applied to the second modulation pixel unit N1 by the second excitation module. N1 The optical properties are altered by controlling the excitation signals output by the first and second excitation modules through the controller, so that the target light wave is modulated in two stages by the spatial light modulator to obtain the target light wave value.

[0055] The following explanation uses the first pixel unit as an example to illustrate the electrical excitation U of the first modulation pixel unit M1. M1 Electrical excitation U of the second modulation pixel unit N1 N1 The decoupling process is as follows:

[0056]

[0057] In the formula, A and P are the amplitude and phase values ​​of the target light wave, respectively, and A0 and P0 are the amplitude and phase values ​​of the incident light wave, respectively; A M1 and P M1 This represents the modulation of the light wave amplitude and the shift in the light wave phase produced by the first modulation pixel unit M1; A N1 and P N1 This represents the modulation of the light wave amplitude and the shift in the light wave phase by the second modulation pixel unit N1; satisfying:

[0058] A M1 = f MA (U M1 )

[0059] P M1 = f MP (U M1 )

[0060] P N1 = f NP (U N1 )

[0061] A N1 = f NA (U N1 )

[0062] f MA (U M1 ) is the amplitude modulation function of the first modulation pixel unit, indicating the amplitude attenuation ratio of the light wave generated by the first modulation pixel unit M1 under the electrical excitation of U M1 f NA (U N1 ) is the amplitude modulation function of the second modulation pixel unit, indicating the amplitude attenuation ratio of the light wave generated by the second modulation pixel unit N1 under the electrical excitation of U N1 f MP (U M1 ) is the phase modulation function of the first modulation pixel unit, indicating the phase shift of the light wave generated by the first modulation pixel unit M1 under the electrical excitation of U M1 f NP (U N1 ) is the phase modulation function of the second modulation pixel unit, indicating the phase shift of the light wave generated by the second modulation pixel unit N1 under the electrical excitation of U N1

[0063] By controlling the parameters such as the width and number of electrical pulses to change the signal excitation strength of the electrical excitation signal, and inputting them into the first modulation pixel unit and the second modulation pixel unit based on the phase change material respectively, the phase state of the phase change material changes, the optical properties of the device change, and the independent dynamic modulation of amplitude and phase information is realized.

[0064] In this embodiment, the first modulation pixel unit and the second modulation pixel unit can adopt the structure based on GST material as shown in Figure 6 The size of the GST material is 600nm x 600nm x 200nm, and the upper and lower sides are transparent electrode material layers. By using the phase change material, different intermediate states with different degrees of crystallization can be generated under different electrical pulse excitation, and the optical properties change in multiple steps, thereby realizing multiple steps of amplitude modulation and phase modulation.

[0065] ​The simulation structure in this embodiment is as follows: Figure 7 As shown, the first modulation layer includes a first modulation pixel unit, and the second modulation layer includes a second modulation pixel unit. The two modulation pixel units are given excitation signals by independent excitation modules, which change the excitation intensity of the signals applied to the first modulation pixel unit and the second modulation pixel unit, thereby changing the amplitude attenuation ratio and phase offset of the two modulation units respectively, and thus controlling the amplitude modulation amount and phase modulation amount of the first modulation pixel unit and the second modulation pixel unit respectively.

[0066] The input light wave in this embodiment is: Target light wave

[0067] The above decoupling algorithm is used to optimize the application of... Figure 7 The simulation results of amplitude and phase obtained from the excitation signals on the first and second modulation pixel units are as follows: the amplitude value of the light wave at the center of the output plane is... The deviation from the target amplitude is 2%; the phase value of the light wave at the center of the output plane is... The deviation from the target amplitude is 5%, such as Figure 8 As shown.

[0068] Will Figure 7 The first modulation pixel unit is set to pure amplitude modulation, and an electrical excitation signal is applied to achieve an amplitude attenuation ratio of 0.2. The second modulation pixel unit is set to pure phase modulation, and an electrical excitation signal is applied to achieve a phase shift of -0.20π. Without using a decoupling algorithm to optimize the excitation signal, the amplitude of the light wave at the center of the output plane is... The deviation from the target amplitude is 36%; the phase value of the light wave at the center of the output plane is... The deviation from the target amplitude is 60%, indicating that the amplitude and phase deviations are too large. Figure 9 As shown.

[0069] As can be seen from the above embodiments, the decoupling algorithm can effectively improve the accuracy of two-stage complex amplitude modulation.

[0070] Example 3

[0071] This embodiment uses different pixel modulation unit structures to demonstrate that the decoupling algorithm can effectively improve the accuracy of two-stage complex amplitude modulation.

[0072] In this embodiment, the first modulation pixel unit and the second modulation pixel unit adopt the following... Figure 10The phase change material-based metasurface structure shown, the substrate is 500nm*500nm*200nm of SiO2 material, the center is placed a GST material cylinder with a radius of 200nm and a height of 200nm, and the cylinder is excited by an independent excitation module. The GST material will produce a variety of intermediate states with different degrees of crystallization under different electrical excitation. The optical properties of the metasurface unit (pixel modulation unit) change in multiple steps under different electrical excitation, thereby realizing multi-step amplitude modulation and phase modulation.

[0073] The simulation structure of the embodiment is shown in Figure 7 The first modulation layer includes a first modulation pixel unit, and the second modulation layer includes a second modulation pixel unit. The two modulation pixel units are excited by independent excitation modules, and the signal excitation applied to the first modulation pixel unit and the second modulation pixel unit is changed to change the amplitude attenuation ratio and the phase shift of the two modulation units, respectively, and then control the amplitude modulation and phase modulation of the first modulation pixel unit and the second modulation pixel unit.

[0074] The signal excitation U M1 applied to the first modulation pixel unit and the signal excitation U N1 applied to the second modulation pixel unit are decoupled, specifically as follows:

[0075]

[0076] In the formula, A and P are the target light wave amplitude value and phase value, respectively, A0 and P0 are the amplitude value and phase value of the incident light wave, respectively; A M1 and P M1 represent the modulation of the first modulation pixel unit M1 to the light wave amplitude and the offset to the light wave phase; A N1 and P N1 represent the modulation of the second modulation pixel unit N1 to the light wave amplitude and the offset to the light wave phase; and satisfy:

[0077] A M1 =f MA (U M1 )

[0078] P M1 =f MP (U M1 )

[0079] P N1 =f NP (U N1 )

[0080] A N1 =f NA (U N1 )

[0081] f MA (U M1 ) is the amplitude modulation function of the first modulation pixel unit, indicating the amplitude attenuation ratio of the light wave generated by the first modulation pixel unit M1 under the electrical excitation of U M1 f NA (U N1 ) is the amplitude modulation function of the second modulation pixel unit, indicating the amplitude attenuation ratio of the light wave generated by the second modulation pixel unit N1 under the electrical excitation of U N1 f MP (U M1 ) is the phase modulation function of the first modulation pixel unit, indicating the phase shift value of the light wave generated by the first modulation pixel unit M1 under the electrical excitation of U M1 f NP (U N1 ) is the phase modulation function of the second modulation pixel unit, indicating the phase shift value of the light wave generated by the second modulation pixel unit N1 under the electrical excitation of U N1 .

[0082] By controlling the parameters such as the width and number of electrical pulses to change the signal excitation strength of the electrical excitation signal, and inputting them into the first modulation pixel unit and the second modulation pixel unit based on the phase change material respectively, the phase state of the phase change material changes, the optical properties of the device change, and the independent dynamic modulation of amplitude and phase information is realized.

[0083] The input light wave of the embodiment is the target light wave According to the above method, the amplitude and phase simulation results obtained by optimizing the excitation level applied to the Figure 7 first modulation pixel unit and the second modulation pixel unit are as follows: the light wave amplitude value at the center of the output plane is , and the deviation from the target amplitude is 5%; the light wave phase value at the center of the output plane is , and the deviation from the target amplitude is 1.54%, as shown in Figure 11 A and Figure 11 B.

[0084] If the first modulation pixel unit in Figure 7 is set to pure amplitude modulation, and the electrical excitation signal is applied so that the amplitude attenuation ratio is 0.20, and the second modulation pixel unit is set to pure phase modulation, and the electrical excitation signal is applied so that the phase shift value is-0.65π, without decoupling optimization, the light wave amplitude value at the center of the output plane is , and the deviation from the target amplitude is 77.5%; the light wave phase value at the center of the output plane is , and the deviation from the target amplitude is 32.9%, it can be seen that the amplitude and phase deviation values are too large.

[0085] From the above examples, it can be seen that the decoupling algorithm can effectively improve the precision of two-stage complex amplitude modulation.

[0086] It should be noted in this embodiment that the structures of the two-layer modulation pixel units do not have to be completely the same. Those skilled in the art should know that, whether it is a phase change material in this embodiment or a metasurface material, it can be used as a modulation pixel unit. Therefore, the phase change material unit in this embodiment can also be replaced by a pixel unit made of a metasurface material, etc.

Claims

1. A phase-amplitude decoupled modulator for complex amplitude modulation, characterized by The application relates to a spatial light modulation device, comprising: a spatial light modulation device, at least comprising a first modulation layer and a second modulation layer; the first modulation layer comprises more than one first modulation pixel unit, and the second modulation layer comprises more than one second modulation pixel unit; a light beam modulated by the first modulation pixel unit is projected to a unique second modulation pixel unit; and a phase-amplitude decoupling modulator, comprising a controller, a first excitation module and a second excitation module; the first excitation module inputs an excitation signal to the first modulation pixel unit; the second excitation module inputs an excitation signal to the second modulation pixel unit; the controller controls the excitation signals of the first excitation module and the second excitation module, specifically: According to the complex amplitude information A n (t,λ) and P n (t,λ), and the initial complex amplitude information of the input light wave at the nth pixel unit, and the phase modulation variation and the amplitude modulation variation of the nth pixel unit, the amplitude attenuation ratio and the phase offset of the nth first modulation pixel unit and the nth second modulation pixel unit are decoupled to obtain the excitation signal applied to the nth first modulation pixel unit and the nth second modulation pixel unit; wherein t represents the time t, and λ represents the incident light wavelength. For any set of pixel cells, the electrical excitation U applied to the first modulating pixel cell M1 M1 and the second modulating pixel cell N1 is: N1 U = U1 - U2 ； where A and P are the amplitude and phase of the target light wave, respectively, and A0 and P0 are the amplitude and phase of the incident light wave, respectively; A M1 and P M1 denote the modulation of the amplitude of the light wave and the shift of the phase of the light wave by the first modulation pixel unit M1; A N1 and P N1 denote the modulation of the amplitude of the light wave and the shift of the phase of the light wave by the second modulation pixel unit N1; and satisfy: A M1 = f MA (U M1 ); P M1 = f MP (U M1 ); P N1 = f NP (U N1 ); A N1 = f NA (U N1 ); f MA (U M1 ) is the amplitude modulation function of the first modulation pixel unit, indicating the amplitude attenuation ratio of the light wave generated by the first modulation pixel unit M1 under the electrical excitation of U M1 f NA (U N1 ) is the amplitude modulation function of the second modulation pixel unit, indicating the amplitude attenuation ratio of the light wave generated by the second modulation pixel unit N1 under the electrical excitation of U N1 f MP (U M1 ) is the phase modulation function of the first modulation pixel unit, indicating the phase shift amount of the light wave generated by the first modulation pixel unit M1 under the electrical excitation of U M1 f NP (U N1 ) is the phase modulation function of the second modulation pixel unit, indicating the phase shift amount of the light wave generated by the second modulation pixel unit N1 under the electrical excitation of U N1 f 2. The modulator of claim 1, wherein, the excitation signal is an electric excitation signal, an optical excitation signal, a stress excitation signal, a thermal excitation signal or other excitation signals.

3. The modulator of claim 1, wherein, the first modulation pixel unit and the second modulation pixel unit are phase change materials, liquid crystal materials or other materials capable of realizing optical property regulation.

4. The modulator of claim 3, wherein, the phase change material is selected from GeSbTe, GeSeSbTe and VO2.

5. The modulator of claim 3, wherein, the liquid crystal material is selected from biphenyl liquid crystal, phenylcyclohexane liquid crystal and ester liquid crystal.

6. The modulator of claim 1, wherein, the first modulation pixel unit is an amplitude modulation unit, and the second modulation unit is a phase modulation unit; or the first modulation pixel unit is a phase modulation unit, and the second modulation unit is an amplitude modulation unit.

7. The modulator of claim 1, wherein, the first modulation pixel unit and the second modulation pixel unit are respectively arranged in an array to form the first modulation layer and the second modulation layer; the first modulation pixel unit and the second modulation pixel unit are in one-to-one correspondence.

8. The modulator of claim 1, wherein, the first excitation module and the second excitation module comprise electrode units, and the electrode units are in one-to-one correspondence with the first modulation layer pixel unit and the second modulation layer pixel unit.

9. The modulator of claim 1, wherein, the first modulation layer and the second modulation layer are seamlessly spliced.

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