CN115128849A - Optical wave complex amplitude modulation device - Google Patents
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- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
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- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
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Abstract
The invention discloses a light wave complex amplitude modulation device which at least comprises a first modulation layer, a second modulation layer and a heat insulation layer positioned between the first modulation layer and the second modulation layer, wherein a light beam modulated by a first modulation pixel unit is projected through a unique heat insulation pixel unit and only projected to a unique second modulation pixel unit. The front and back two-stage modulation of two complex amplitude modulation pixels is realized by arranging a unique heat insulation pixel unit for accurate projection. The two-stage dynamic complex amplitude modulation is an ideal technical path with optimal performance in all aspects and greatly simplified structure, and can break through various benefits of low amplitude and phase modulation level, mutual interference, complex preparation process and the like, and independent and multi-stage complex amplitude complete information reconstruction of amplitude modulation and phase modulation and space-time separation of the amplitude and phase modulation processes can be respectively realized, so that the performances of resolution, amplitude distribution uniformity, precision, signal-to-noise ratio and the like are improved, and the dynamic switching of images and the improvement of reconstructed image quality are completed.
Description
Technical Field
The invention relates to the technical field of optics, in particular to a light wave complex amplitude modulation device.
Background
The complex amplitude modulation technology records and reconstructs all wave information of a certain target and an object by modulating the complex amplitude information of light waves, has important application prospect in the fields of holographic technology, spatial light modulator and the like, and is widely applied to 3D display, interferometry, military reconnaissance monitoring, information storage, medical detection and other defense military and real life.
The static complex amplitude modulation technology is a common complex amplitude modulation technology in the prior art, the modulation effect of the static complex amplitude modulation technology is fixed when a modulation device structure is generated, the modulation effect cannot be adjusted, and only a determined reconstructed image can be generated. The dynamic complex amplitude modulation can dynamically adjust the light wave information and output a dynamically changed sequence image on the premise of not changing the structure of the device. In the prior art, dynamic complex amplitude modulation is based on an excitation signal on a modulation unit structure, so that the refractive index and the extinction coefficient of the modulation unit structure are changed, and the amplitude value and the phase value of an optical wave are modulated.
Due to the mutual interference of the amplitude modulation effect and the phase modulation effect, the dynamic complex amplitude modulation unit (single-factor dynamic modulation) modulated by one electric excitation cannot obtain the required amplitude and phase combination, namely cannot obtain the required complex amplitude value.
Optimizing the modulation unit structure to achieve dynamic modulation is a major research direction of researchers at present. For example, the size of the dynamic complex amplitude modulation unit is increased, and multi-order amplitude and phase changes of the unit structure are realized to a certain extent, so that the complex amplitude value of the optical wave is more finely modulated. However, the increase of the cell size leads to the decrease of the resolution of the whole device, which is contrary to the trend of high resolution and high precision of the complex amplitude modulation technology.
After the first modulation layer carries out pixelization modulation on the optical wave phase, the transmission direction of the optical wave modulated by different units is changed, and the problem of optical information crosstalk between two-level modulation layers is inevitably generated. In order to solve the problem, in the prior art, incident light is limited to be parallel light, and primary modulation is pure amplitude modulation, only the intensity of light is changed, and the phase of the light is not changed, that is, the transmission direction of the light beam after the pure amplitude modulation is unchanged, and emergent light is still the modulation effect of the parallel light after the modulation of an amplitude modulator. However, the pure amplitude modulation unit has complex design, large unit size and high manufacturing cost, and the feasibility of the scheme is greatly reduced.
Disclosure of Invention
The invention aims to provide an optical wave complex amplitude modulation device which does not lean on the dynamic modulation effect of a modulation unit, 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 regulation and control.
Further, thermal crosstalk inevitably exists in the second-order dynamic regulation of the modulation unit, and in the initial scheme of the invention, high-precision modulation cannot be realized through a conventional thermal insulation layer all the time. Through intensive research of a team, the problem of optical information crosstalk caused by diffraction of a light beam on the interface of the first modulation layer and the thermal insulation layer and the optical path difference factor of the thermal insulation layer are important factors causing the imperfection of the initial scheme of the invention. To date, none of the prior art discloses or relates the above factors and related factors to complex amplitude modulation.
Specifically, the invention adopts the following technical scheme: the modulation device at least comprises a primary modulation of a first modulation layer and a secondary modulation of a second modulation layer, wherein 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 by a unique heat insulation pixel unit and is projected to only a unique second modulation pixel unit for secondary modulation; when the number of the heat insulation pixel units is two or more, the optical path of each heat insulation pixel unit is the same.
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 amplitude modulation unit is a pixel modulation unit for regulating amplitude by emphasis, and the phase modulation unit is a pixel modulation unit for regulating phase by emphasis. For example, the amplitude modulation units used are: under the control of electric excitation, the modulation of the optical wave amplitude is uniformly and multi-step changed in the range of 0-1, and the change quantity of the optical wave phase is within +/-pi/5; the phase modulation unit is as follows: under the control of electric excitation, the modulation of the optical wave phase is changed uniformly and in multiple steps in the range of 0-2 pi, and the change quantity of the optical wave amplitude is stable, and the fluctuation value is within 10%.
Further, the first modulation pixel unit and the second modulation pixel unit change their optical properties by additionally introduced signal stimuli (electrical stimuli, optical stimuli, etc.), which effect the modulation of the light beam.
It should be noted that: the optical properties of the modulation pixel unit refer to various properties of the modulation pixel unit when the modulation pixel unit absorbs, reflects, refracts, scatters and diffracts light, the optical properties of the modulation pixel unit change when the modulation pixel unit is excited by an excitation signal (for example, the phase-change material is excited by an electric signal), the various properties of the modulation pixel unit when the modulation pixel unit absorbs, reflects, refracts, scatters and diffracts light change, and the corresponding amplitude attenuation ratio and phase offset amount also change. Therefore, materials that enable the modulation of optical properties, such as phase change materials, liquid crystal materials, etc., can be used as the modulating pixel cells of the present application.
That is, after an excitation signal, the optical properties of a modulation pixel unit, such as refractive index and extinction coefficient, change, and the corresponding amplitude attenuation ratio and phase shift amount also change (see fig. 4). The skilled person can derive the required excitation signal from the required amplitude attenuation ratio and phase offset by back-calculation, thereby achieving a higher accuracy of modulation. The invention further modulates the excitation signals of the first modulation pixel unit and the second modulation pixel unit by the following method: according to the complex amplitude information A of the target light wave in the nth pixel unit n (t, lambda) and P n (t, lambda), eliminating the initial complex amplitude information of the input light wave in the nth pixel unit
And
obtaining the phase modulation variation and the amplitude modulation variation of the nth pixel unit, decoupling to obtain the amplitude attenuation ratio and the phase offset of the nth first modulation pixel unit and the nth second modulation pixel unit, obtaining the optical properties such as the refractive index and the extinction coefficient of the nth first modulation pixel unit and the nth second modulation pixel unit, and finally obtaining the excitation signals applied to the nth first modulation pixel unit and the nth second modulation pixel unit
And
after an excitation signal, the optical properties of a modulation pixel unit, such as the refractive index and the extinction coefficient, can be obtained by simple means, and even the excitation signal-optical property relation function (as shown in fig. 4) can be obtained by simple tests. The field performs inverse estimation based on the function to obtain the required excitation signal.
The principle of decoupling is: the phase information of the light wave in the nth pixel unit is simultaneously modulated by the nth first modulation pixel unit and modulated by the nth second modulation pixel unit, and the phase difference between the target light wave and the incident light wave of 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 of the target light wave and the incident light wave of the nth pixel modulation unit is simultaneously modulated by the nth first modulation pixel unit and the nth second modulation pixel unit, and the amplitude attenuation ratio of 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.
Furthermore, the first modulation pixel unit, the second modulation pixel unit and the heat insulation pixel unit respectively form an array. In the three arrays, the first modulation pixel unit, the second modulation pixel unit and the heat insulation pixel unit have unique one-to-one correspondence.
Further, the thermally isolated pixel unit is an optical guiding structure (including but not limited to optical fiber, photonic crystal, and optical grating) configured to guide the primarily modulated light beam to the second modulation pixel unit for secondary modulation. The heat insulating property of the light guiding structure can be achieved by selecting a suitable material or designing a suitable structure, which is not specifically described in the present application.
The invention has the beneficial effects that: the invention realizes the front and back two-stage modulation of two complex amplitude modulation pixels by arranging a unique heat insulation pixel unit for accurate projection. The Two-stage dynamic complex amplitude modulation is an ideal technical path with optimal performance in all aspects and greatly simplified structure, simultaneously realizes the functions of dynamic modulation, Two-stage (Two-stage) independent modulation of phase and amplitude and the like of an image, and can obtain high-quality wavefront reconstruction of a real holographic dynamic image. The method breaks through various limitations of low amplitude and phase modulation level, mutual interference, complex preparation process and the like, and can respectively realize independent and multi-level (multi-level) amplitude modulation and complex amplitude complete information reconstruction of phase modulation, and spatial-temporal separation of the amplitude and phase modulation processes, thereby improving the performances of resolution, amplitude distribution uniformity, precision, signal-to-noise ratio and the like, and completing dynamic switching of images and improvement of reconstructed image quality.
Drawings
FIG. 1 is a first modulating pixel cell of example 1 employing a digital super surface structure based on phase change materials, different crystalline/amorphous combinations;
FIG. 2 is a graph of complex amplitude modulation of the first modulated pixel cell of FIG. 1 with different electrical stimulus intensities applied, FIG. 2A showing the amount of adjustment with different amplitudes of the electrical stimulus intensities, and FIG. 2B showing the amount of adjustment with different phases of the electrical stimulus intensities;
FIG. 3 is a second modulating pixel cell of example 1 employing a digital super surface structure based on phase change materials, different crystalline/amorphous combinations;
FIG. 4 is a graph of complex amplitude modulation of a second modulated pixel element of FIG. 3 with different levels of electrical stimulus application, FIG. 4A showing the amount of modulation with different phases of the electrical stimulus application, and FIG. 4B showing the amount of modulation with different amplitudes of the electrical stimulus application;
fig. 5 is a structure of a complex amplitude modulation device in embodiments 2, 3;
fig. 6 is a cell structure adopted by the first modulation pixel unit and the second modulation pixel unit in embodiments 2 and 3;
FIG. 7 is a unit structure of an insulating interlayer used in examples 2 and 3;
fig. 8 is a simulation cell structure employed in embodiments 2, 3;
FIG. 9 is a simulation result of two-stage complex amplitude modulation using the heat insulating intermediate layer without using the decoupling algorithm in example 2, FIG. 9A is an amplitude value distribution diagram of the light wave output plane, and FIG. 9B is a phase value distribution diagram of the light wave output plane;
FIG. 10 is a simulation cell structure of example 2 without using an insulating interlayer and without using a decoupling algorithm;
FIG. 11 is a simulation result of two-stage complex amplitude modulation without using a heat insulating intermediate layer and without using a decoupling algorithm in example 2, FIG. 11A is an amplitude value distribution diagram of a lightwave output plane, and FIG. 11B is a phase value distribution diagram of the lightwave output plane;
fig. 12 is a simulation result of two-stage complex amplitude modulation using a decoupling algorithm using a heat insulating intermediate layer in example 3, fig. 12A is an amplitude value distribution diagram of a lightwave output plane, and fig. 12B is a phase value distribution diagram of the lightwave output plane.
Detailed Description
Example 1
The present embodiment takes two-stage modulation pixel units in front and back as an example, and illustrates the unique advantage of two-stage regulation in improving the complex amplitude dynamic modulation precision.
FIG. 1 shows a first modulation pixel cell of this embodiment, which employs a phase change material based digital super surface cell structure, wherein the substrate is a 1600nm × 1600nm Si material, and four 800nm high GSST (Ge2Sb2Se4Te) cylinders with different sizes and radii d 1 ＝425nm，d 2 ＝220nm，d 3 ＝205nm，d 4 230nm, an electric excitation source is arranged below each GSST cylinder, and the crystalline state/amorphous state of each GSST material can be independently controlled. The tested communication wavelength is 1550nm, and the modulation amounts of the amplitude modulation digital super surface unit (first modulation pixel unit) on the amplitude and the phase of the light wave in the area under the different crystalline/amorphous combinations of four GSST materials are shown in FIGS. 2A and 2B, and the data thereof is shown in Table 1 (the diameter is d by ABCD respectively) 1 、d 2 、d 3 And d 4 GSST cylinder of (a):
table 1: modulation amounts of amplitude and phase of light wave by amplitude modulation digital super surface unit (first modulation pixel unit) in embodiment 1
FIG. 3 is a second modulation pixel cell in this embodiment, using a phase change material based digital super surface structure, where the substrate is a 1600nm Si material, and four 800nm high GSST (Ge2Sb2Se4Te) cylinders of different sizes are placed on it, with respective radii D 1 ＝470nm，D 2 ＝435nm，D 3 ＝410nm，D 4 365nm, an electric excitation source is arranged below each GSST cylinder, and the crystalline state/amorphous state of each GSST material can be controlled independently. The communication wavelength of each test is 1550nm, and the modulation amounts of the phase modulation digital super surface unit (second modulation pixel unit) to the amplitude and the phase of the light wave in the area under different crystalline/amorphous combinations of four GSST materials are shown in FIGS. 4A and 4B, and the data thereof is shown in Table 2 (WXYZ represents the diameter D 1 、D 2 、D 3 And D 4 GSST cylinder of (a):
table 2: embodiment 1 is a phase modulation digital super surface unit (second modulation pixel unit) for modulating the amplitude and phase of an optical wave
The single first modulation pixel unit has eight different amplitude modulation amounts and three different phase modulation amount changes, and eight different complex amplitude values are shared; the individual second modulation pixel units have eight different amplitude, different phase complex amplitude values. After the combination, the range of the complex amplitude modulation which can be modulated is expanded to 8 × 8 types. Assuming that the incident light is a plane wave of a vertical incidence device, the phase is 0, the amplitude is 1, and all amplitude values of the light wave obtained by all different crystalline/amorphous combinations of the first modulation pixel unit and the second modulation pixel unit are shown in table 3:
table 3: all light wave amplitude modulation values obtained by different crystalline/amorphous combination
| 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 |
All phase values of the optical wave obtained by all different crystalline/amorphous combinations of the amplitude dynamic modulation unit and the phase dynamic modulation unit are shown in table 4 and table 3:
table 4: all optical wave phase modulation values obtained by different crystalline/amorphous combinations
From the above, by changing the excitation modes of the first modulation pixel unit and the second modulation pixel unit and selecting different crystalline/amorphous combinations, the eight amplitude phase combinations of the original one-level modulation can be expanded to obtain 64 amplitude phase modulation combinations, and the precision of the optical wave complex amplitude modulation is greatly improved.
Those skilled in the art should understand that the present embodiment can be equally replaced by other PCM microstructures, and can also achieve the technical effects of the present embodiment with high precision, such as rod-shaped, V-shaped, cross-shaped, C-shaped structures, etc., and the thickness is in the range of 50-600 nm. The PCM microstructures are arranged and combined, and each microstructure is provided with an independent electric excitation source, so that mutual transformation between crystalline states and amorphous states of each microstructure can be realized, the optical property of the first modulation pixel unit is changed, and the phase modulation amount and the amplitude modulation amount of the whole digital super-surface unit (modulation pixel unit) are changed. In addition, a plurality of PCM microstructures with different shapes can be respectively placed on a substrate to form a digital super-surface unit, each microstructure is electrically excited to generate the change of the refractive index and the extinction coefficient under different phase combinations, so that the change of the amplitude attenuation ratio and the phase offset of the digital super-surface unit is realized, each change value is coded, and the near-continuous multi-order phase change in the [0,2 pi ] full range and the near-continuous multi-order amplitude change in the [0,1] full range can be realized.
In the present application, each modulation pixel unit on the first modulation layer and the second modulation layer is regulated and controlled by an independent signal excitation source, and the units do not interfere with each other.
Example 2
As shown in fig. 5 and 5, the present embodiment provides a complex amplitude dynamic modulator, which includes a first modulation layer and a second modulation layer, and a thermal insulation layer located therebetween, where the first modulation layer has first modulation pixel units M1 to M3, the second modulation layer has second modulation pixel units N1 to N3, and the thermal insulation layer has thermal insulation pixel units I1 to I3, and the first modulation pixel unit, the second modulation pixel unit, and the thermal insulation pixel unit each form an array, and each unit corresponds to one another.
After being modulated for the first time by the first modulation pixel unit M1 of the first modulation layer of the device, the local light wave is constrained by the heat insulation pixel unit I1 with the light guide structure adjacent to the first modulation pixel unit M1, so that all light beams modulated by the first modulation pixel unit M1 can be completely and accurately projected and only projected into the second modulation pixel unit N1 of the second modulation layer for the second time modulation; similarly, the specific area light beam primarily modulated at the first modulation pixel cell M2 of the first modulation layer of the device is secondarily modulated after being guided through the adiabatic pixel cell I2 adjacent to the first modulation pixel cell M2 and projected only into the second modulation pixel cell N2 of the second modulation layer.
In this embodiment, the first modulation pixel unit and the second modulation pixel unit may adopt a structure based on a phase change material as shown in fig. 6, where the phase change material is a GST material, the size of the GST material is 600nm × 600nm × 200nm, and the upper and lower sides are transparent electrode material layers. The GST material can generate a plurality of intermediate states with different degrees of crystallinity under the excitation of different electric pulse intensities, and the complex refractive index is changed in multiple stages, so that the amplitude modulation amount and the phase modulation amount in multiple stages are realized.
In this embodiment, the heat-insulating pixel unit adopts a micrometer-scale light guide fiber structure as shown in fig. 7, the refractive index of the cladding is greater than that of the fiber core, and the light beam is enveloped and transmitted, so that the light wave modulated by the first modulation pixel unit is completely and accurately projected onto the only second modulation pixel unit. In order to ensure the precision, the optical path difference of each heat insulation pixel unit can be ensured to be consistent by finely adjusting parameters such as the thickness, the structure, the material and the like of the heat insulation pixel unit.
The present embodiment was simulated by a simulation model in which a heat insulating interlayer was disposed as shown in fig. 8, and the optical properties of the two modulation cells were changed by changing the excitation signals applied to the first modulation pixel cell and the second modulation pixel cell, respectively. The input light wave of this example is
Target light wave
The amplitude value of the output plane central light wave is about 0.021, and the deviation is 34.4%; the phase value is about 0.608 pi, the deviation from the target phase value is 21.6%, and the simulation result is shown in fig. 9.
Fig. 10 is a two-stage complex amplitude modulation scheme without an intermediate thermal barrier layer, applying the same electrical excitation as fig. 8. The amplitude value of the central light wave of the output plane is about 0.025, and the deviation is 21.9%; the phase value is about 0.56 pi and deviates 12% from the target phase value; the simulation results are shown in fig. 11.
According to the embodiment, the intermediate heat insulation layer can greatly improve the precision of the optical complex amplitude modulation.
Example 3
In this embodiment, the first modulation pixel unit and the second modulation pixel unit may adopt a structure based on a phase change material as shown in fig. 6, wherein the phase change material is a GST material, the size of the phase change material is 600nm × 600nm × 200nm, and the upper and lower sides are transparent electrode material layers. The GST material can generate a plurality of intermediate states with different crystallization degrees under the excitation of different electric pulse intensities, and the refractive index and the extinction coefficient are changed in multiple steps, so that the amplitude modulation amount and the phase modulation amount in multiple steps are realized.
In this embodiment, the heat-insulating pixel unit may adopt a micrometer-scale light-guiding fiber structure as shown in fig. 7, the refractive index of the cladding is greater than that of the fiber core, and the light beam is enveloped and transmitted, so that the light wave modulated by the first modulation pixel unit is completely and accurately projected onto the only second modulation pixel unit. In order to ensure the precision, the optical path difference of each heat insulation pixel unit can be ensured to be consistent by finely adjusting parameters such as the thickness, the structure, the material and the like of the heat insulation pixel unit.
On the basis of the two-level modulation of embodiment 2 to improve the accuracy, this embodiment further optimizes the excitation signals including the electrical excitation of each first modulation pixel unit and the electrical excitation of each second modulation pixel unit by using a decoupling algorithm. The electrical stimulus U of the first modulating pixel cell M1 will be described using the first pixel cell as an example M1 And electrical excitation U of the second modulation pixel cell N1 N1 The decoupling process of (2) is as follows:
wherein A and P are respectively the amplitude value and phase value of the target light wave, A 0 And P 0 Amplitude values and phase values of the incident light waves, respectively; a. the M1 And P M1 Represents the modulation of the amplitude of the optical wave and the offset of the phase of the optical wave by the first modulation pixel unit M1; a. the N1 And P N1 Represents the modulation of the amplitude of the optical wave and the shift of the phase of the optical wave by the second modulation pixel unit N1; satisfies the following conditions:
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 ) For the first modulation pixelThe amplitude modulation function of the element, indicating that the first modulated pixel cell M1 is at U M1 The amplitude attenuation ratio of the generated light wave is reduced under the electric excitation of (2). f. of NA (U N1 ) Represents the second modulation pixel element N1 at U as an amplitude modulation function of the second modulation pixel element N1 The amplitude attenuation ratio of the generated light wave is reduced under the electric excitation of (2). f. of MP (U M1 ) Indicating that the first modulation pixel element M1 is at U as a function of the phase modulation of the first modulation pixel element M1 The phase shift of the generated optical wave is generated under the electric excitation of the optical sensor. f. of NP (U N1 ) The phase modulation function of the second modulation pixel element, indicating that the second modulation pixel element N1 is at U N1 Under the electric excitation, the phase shift of the generated light wave
The excitation intensity of the electric excitation signal is changed by controlling parameters such as the width and the number of electric pulses, and the electric excitation signal is respectively input into the first modulation pixel unit and the second modulation pixel unit based on the phase-change material, so that the phase-change material is subjected to phase change, the optical property of the device is changed, and the independent dynamic modulation of amplitude and phase information is realized.
In this embodiment, simulation is performed, and the simulation model is as shown in fig. 8, and the signal excitation intensities applied to the first modulation pixel unit and the second modulation pixel unit are changed, so as to change the optical properties of the two modulation units, respectively, and further control the amplitude modulation amount and the phase modulation amount of each of the first modulation pixel unit and the second modulation pixel unit.
The input light wave of this example is the same as example 2,
target light wave
After the excitation signal is optimized by adopting the decoupling algorithm, the obtained simulation result is as follows: the amplitude value of the light wave at the center of the output plane is
Deviation from target amplitude was 3.1%; optical phase value at the center of the output planeIs composed of
The deviation from the target amplitude was 2%, as shown in fig. 12.
Compared with the simulation result which contains the middle layer and does not adopt the decoupling algorithm in the embodiment 2, the error between the simulation result of the embodiment and the expected complex amplitude value is greatly reduced. According to the embodiments, the decoupling algorithm can greatly improve the precision of the optical wave complex amplitude modulation and the degree of freedom of the modulation.
It should be noted that the structures of the two layers of modulation pixel units are not necessarily identical. Those skilled in the art will appreciate that either phase change material or super surface material can be used as the modulating pixel cell in this embodiment. Therefore, the phase change material cell in the present embodiment may also be replaced with a pixel cell or the like made of a super surface material.
Claims (11)
1. An optical wave complex amplitude modulation device is characterized by at least comprising a first modulation layer, a second modulation layer and a heat insulation layer positioned between the first modulation layer and the 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 heat insulation layer comprises one or more heat insulation pixel units, and the light beams modulated by the first modulation pixel units are projected by one unique heat insulation pixel unit and projected only to a unique second modulation pixel unit.
2. The optical complex amplitude modulation device according to claim 1, wherein the number of the adiabatic pixel units is two or more, and the optical path lengths of the respective adiabatic pixel units are the same.
3. The optical complex amplitude modulation device according to 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.
4. The device according to claim 1, wherein the first and second modulation pixel cells are phase change material, liquid crystal material, or other material capable of achieving optical property modulation.
5. The optical complex amplitude modulation device of claim 3, wherein the phase change material is selected from the group consisting of: GeSbTe, GeSeSbTe, VO 2.
6. The optical complex amplitude modulation device of claim 3, wherein the liquid crystal material is selected from the group consisting of: biphenyl liquid crystal, phenylcyclohexane liquid crystal and ester liquid crystal.
7. The optical complex amplitude modulation device of claim 1, wherein the first modulation pixel unit, the second modulation pixel unit, and the thermal isolation pixel unit are respectively formed in an array.
8. The device according to claim 1, wherein the thermal isolation unit is a light guiding structure configured to guide the light beam modulated by the first modulation pixel unit to the second modulation pixel unit for modulation.
9. The device of claim 1, wherein the thermally isolated pixel cells are optical fibers, photonic crystals, gratings, or other light-guiding structures.
10. The optical complex amplitude modulation device of claim 1, wherein the first modulation pixel unit and the second modulation pixel unit change their optical properties by signal excitation, thereby realizing modulation of the light beam.
11. The optical complex amplitude modulation device of claim 10 wherein the excitation signals of the first and second modulation pixel cells are further modulated by: obtaining the phase modulation variation and amplitude modulation variation of the nth pixel unit according to the complex amplitude information A ^ n (t, lambda) and P ^ n (t, lambda) of the target light wave in the nth pixel unit and the initial complex amplitude information A _0^ n (t, lambda) and P _0^ n (t, lambda) of the input light wave in the nth pixel unit, decoupling to obtain the amplitude attenuation ratio and the phase offset of the nth first modulation pixel unit and the nth second modulation pixel unit, and finally obtaining the excitation signals applied to the nth first modulation pixel unit and the nth second modulation pixel unit.
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