Optical field multi-dimensional modulation device, preparation method and application thereof

Abstract

The application discloses a kind of light field multidimensional modulation devices, preparation method and its application.The device includes first substrate, second substrate, first electrode layer, second electrode layer, first orientation layer, second orientation layer and blue phase liquid crystal layer;Blue phase liquid crystal layer includes liquid crystal and polymer mixed layer, wherein rod-shaped liquid crystal molecules form double helix twist prisms, the chirality of prisms determines the polarization of modulated light field;Double helix twist prisms are three-dimensionally packed to form cubic lattice structure, and the lattice constant of cubic lattice structure corresponds to determine the wavelength of modulated light field, and the crystal face orientation angle of cubic lattice structure determines the phase of modulated light field.The application realizes the efficient modulation of blue phase liquid crystal to light field polarization, wavelength, phase and intensity by flexible control to multi-level, cross-scale structure, provides the feasibility of optical multidimensional independent control, can be applied to optical computing, optical communication, hyperspectral imaging, color holographic display and other fields, and promotes the development of existing optical system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical devices, in particular to a light field multi-dimensional modulation device, a preparation method and application thereof. BACKGROUND

[0002] In the rapidly changing era of big data, new technologies such as artificial intelligence, 5G / 6G communication, autonomous driving, virtual / augmented reality, and holographic display have marked the increasing demand for ultra-high capacity information processing, transmission, and interaction capabilities. In order to break the deadlock of limited information processing capacity by electricity, optical communication and optical computing using light as a medium are widely recognized as transformative technologies in the future information field. Through independent control of each degree of freedom of the light field, parallel processing of multi-dimensional information can be achieved, increasing channel bandwidth and laying the foundation for high-speed, high-capacity optical information processing capabilities. Currently, independent, accurate, and efficient coding of each dimension of the light field has become a core problem in the field of optical information technology.

[0003] Blue phase liquid crystal, as a special liquid crystal phase state with three-dimensional periodic structure, its chirality, lattice constant and lattice azimuth angle correspond to the polarization, wavelength and phase information of the modulated light field, respectively, which can realize independent control of multi-dimensional light field and avoid the problems of low efficiency and low flexibility caused by cross-talk between dimensions. At the same time, the optical device prepared by using blue phase liquid crystal for multi-dimensional light field modulation has unique narrow photonic bandgap, wide viewing angle polarization selectivity and full-range light field modulation characteristics, which can realize narrow-band, wide-angle and multi-dimensional mode loading, and has wide application prospects in virtual / augmented reality, full-color holographic display, intelligent car lights, hyperspectral imaging and other fields.

[0004] However, the efficiency of blue phase liquid crystal for light field modulation is greatly limited by the uniformity of the patterned blue phase liquid crystal domain structure. In recent years, through electrical, optical and thermal control, a variety of methods for preparing blue phase single domains have been derived, but none of them have solved the problem of combining single domains with patterning. Therefore, if blue phase liquid crystal is to be applied to multi-dimensional light field modulation optical devices and play its unique role in narrow-band, wide-angle and full-range light field modulation, how to efficiently and simply prepare patterned single-domain blue phase liquid crystal has become a problem to be solved. SUMMARY

[0005] The embodiments of the present application provide a light field multi-dimensional modulation device, a preparation method and application thereof. The device can efficiently modulate the polarization, wavelength and phase of the light field, providing the feasibility of independent control of multi-dimensional light field in planar optics, and can be applied to the fields of optical computing, optical communication, hyperspectral imaging, color holographic display, etc., further promoting the upgrading and development of existing optical systems.

[0006] According to an aspect of the present application, a light field multi-dimensional modulation device is provided for independently modulating the polarization, wavelength and phase information of the light field, comprising:

[0007] The first substrate, the second substrate and the blue phase liquid crystal layer between the first substrate and the second substrate are oppositely arranged;

[0008] The first substrate is provided with a first electrode layer on one side thereof, and is provided with a first orientation layer on the side close to the second substrate; the second substrate is provided with a second electrode layer on one side thereof, and is provided with a second orientation layer on the side close to the first substrate;

[0009] The blue phase liquid crystal layer comprises a liquid crystal and polymer mixed layer, wherein nanometer scale rod-shaped liquid crystal molecules in the liquid crystal and polymer mixed layer form tens of nanometer scale double helix twisted prisms under the induction of chiral strength of the material system; the double helix twisted prisms are three-dimensionally stacked to form a hundred nanometer scale cubic lattice structure;

[0010] The first orientation layer and the second orientation layer comprise a preset planar arrangement orientation pattern, and the orientation pattern induces the cubic lattice structure to self-assemble according to a preset orientation;

[0011] The spatial chirality of the double helix twisted prisms determines the polarization of the modulated light field, and light matching the chirality of the double helix twisted prisms is reflected, and light opposite to the chirality of the double helix twisted prisms is transmitted;

[0012] The lattice constant of the cubic lattice structure determines the wavelength of the modulated light field, and the lattice constant of the cubic lattice structure is controlled by controlling the material ratio and / or external conditions to adjust the wavelength of the reflection center, and the larger the lattice constant of the cubic lattice structure is, the longer the wavelength of the modulated light field is;

[0013] The crystal face orientation of the cubic lattice structure determines the phase of the modulated light field, and the crystal face orientation of the cubic lattice structure is controlled by external conditions to modulate the phase of the reflected light.

[0014] Optionally, the initial chirality of the double helix twisted prisms is determined by the chirality of the chiral agent doped in the liquid crystal and polymer mixed layer; and the initial lattice constant of the cubic lattice is determined by the concentration of the chiral agent doped in the liquid crystal and polymer mixed layer.

[0015] Optionally, the range of the blue phase liquid crystal grain boundary is controlled by controlling the structural uniformity of the liquid crystal and polymer mixed layer by external conditions to modulate the amplitude of the light field

[0016] Optionally, the external conditions include an electric field, a light field or a temperature adjustment.

[0017] Optionally, the liquid crystal and polymer mixed layer comprises a nematic liquid crystal, a chiral agent, a polymer monomer and a photoinitiator.

[0018] Optionally, the first electrode layer is located on a side of the first substrate close to the second substrate or between the first substrate and the first alignment layer.

[0019] The second electrode layer is located on a side of the second substrate close to the first substrate or between the second substrate and the second alignment layer.

[0020] Optionally, the device further comprises spacer particles between the first substrate and the second substrate, the spacer particles comprising at least one of quartz microspheres and quartz columns.

[0021] Optionally, the first alignment layer and the second alignment layer comprise at least one of photo-crosslinking material, photo-degradation material and photo-isomerization material, the control pattern of the first alignment layer and the second alignment layer being erasable, and the thickness of the alignment layer ranging from 30 nm to 50 nm.

[0022] According to another aspect of the present application, a preparation method of a light field multi-dimensional modulation device is provided, for preparing the light field multi-dimensional modulation device as described above, comprising:

[0023] providing a first substrate and a second substrate;

[0024] forming a first electrode layer on a side of the first substrate, forming a first alignment layer on a side of the first substrate close to the second substrate, forming a second electrode layer on a side of the second substrate, and forming a second alignment layer on a side of the second substrate close to the first substrate;

[0025] encapsulating the first substrate and the second substrate;

[0026] filling a liquid crystal and polymer mixed layer in an isotropic phase between the first substrate and the second substrate;

[0027] wherein the first alignment layer and the second alignment layer have a control pattern of liquid crystal molecule director distribution, and under the joint action of the first alignment layer and the second alignment layer, the cubic lattice structure composed of double helix structure columns in the liquid crystal and polymer mixed layer is induced to self-assemble according to a preset orientation;

[0028] placing the encapsulated device on a hot stage, changing the temperature to make the liquid crystal and polymer mixed layer undergo a phase transition process from the isotropic phase to the blue phase II to the blue phase I or from the isotropic phase to the blue phase I;

[0029] applying an alternating electric field perpendicular to the first substrate between the first electrode layer and the second electrode layer, in combination with the influence of the temperature and the first alignment layer and the second alignment layer, the order degree of the cubic lattice structure arrangement of the liquid crystal and polymer mixed layer is increased, forming a blue phase liquid crystal single domain structure.

[0030] Optionally, after the liquid crystal and polymer mixed layer is poured between the first substrate and the second substrate, a method of ultraviolet polymerization is adopted to obtain a stable single-domain blue phase liquid crystal at room temperature.

[0031] According to another aspect of the present application, an application based on the above-mentioned light field multi-dimensional modulation device is provided, phase information is loaded into different regions of different color blue phase liquid crystal samples by light control orientation, and pseudo-dynamic switching of RGB color holographic display can be realized by changing positions.

[0032] The light field multi-dimensional modulation device provided by the embodiment of the present application comprises a first substrate and a second substrate arranged oppositely, a first electrode layer, a second electrode layer, a first orientation layer, a second orientation layer and a blue phase liquid crystal layer between the first substrate and the second substrate; the helical prism chirality, the cubic lattice constant and the crystal face orientation angle distribution of the blue phase liquid crystal layer correspond to the polarization, wavelength and phase information of the modulated light field respectively, and the multi-dimensional tunable light field can be realized by adjusting material parameters and applying a multi-element external field. The embodiment of the present application realizes efficient modulation of the polarization, wavelength, phase and intensity of the light field by the blue phase liquid crystal through flexible control of the multi-level and cross-scale structure, provides the feasibility of independent control of optical multi-dimensions, can be applied to the fields of optical computing, optical communication, high-spectral imaging, color holographic display and the like, and further promotes the development of existing optical systems.

[0033] It should be understood that the content described in this part is not intended to identify key or important features of the embodiments of the present application, nor is it used to limit the scope of the present application. Other features of the present application will become apparent through the following description. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0035] Figure 1 A structural schematic diagram of a light field multi-dimensional modulation device provided by the embodiment of the present application;

[0036] Figure 2 A polarized light microscope comparison diagram of light control orientation and unoriented blue phase liquid crystal domain state in the embodiment of the present application;

[0037] Figure 3 A polarized light microscope diagram of a green single-domain blue phase liquid crystal preparation method in the embodiment of the present application;

[0038] Figure 4 A reflection spectrum diagram corresponding to the red, green and blue three-color single-domain blue phase liquid crystal in the embodiment of the present application;

[0039] Figure 5 A temperature rising and falling test diagram of the blue, green and red three-color samples after the operation of the single-domain blue phase liquid crystal stabilized by the polymer in the embodiment of the present application;

[0040] Figure 6 A liquid crystal director direction radial distribution diagram of the wide-viewing-angle polarization selection grating in the embodiment of the present application, and a corresponding orthogonal polarized light microscope diagram of the red wide-viewing-angle polarization grating;

[0041] Figure 7 A diffraction light path diagram of the wide-viewing-angle polarization selection grating in the embodiment of the present application;

[0042] Figure 8 A diffraction pattern diagram of the wide-viewing-angle polarization selection grating in the embodiment of the present application under different angles and different polarization states of incidence;

[0043] Figure 9 A design diagram of two full-color holograms in the embodiment of the present application;

[0044] Figure 10 An orthogonal polarized light microscope (POM) diagram and a diffraction pattern diagram of different regions of the blue phase liquid crystal sample of different colors in the embodiment of the present application;

[0045] Figure 11 A diffraction effect diagram of the layering of different regions of the blue phase liquid crystal sample of different colors in the embodiment of the present application;

[0046] Figure 12 A flowchart of a preparation method of a light field multi-dimensional modulation device provided in the embodiment of the present application. DETAILED DESCRIPTION

[0047] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should fall within the scope of protection of the present application.

[0048] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting, unless the context clearly indicates otherwise. It will be further understood that the use of relational terms such as first and second, and the like are used solely to distinguish one from another entity without necessarily implying a relationship or order between such entities. Much of the detail of the embodiments described in this detailed description is conventional or well understood in the art and is not described in detail to avoid obscuring the description of the embodiments of the application.

[0049] Figure 1 The embodiment of the application provides a structural schematic diagram of a light field multi-dimensional modulation device. Figure 1 The light field multi-dimensional modulation device comprises a first substrate 1, a second substrate 2 and a blue phase liquid crystal layer 3 located between the first substrate 1 and the second substrate 2 which are oppositely arranged; one side of the first substrate 1 is provided with a first electrode layer (not shown in the figure), one side of the first substrate 1 close to the second substrate 2 is provided with a first orientation layer (not shown in the figure), one side of the second substrate 2 is provided with a second electrode layer (not shown in the figure), and one side of the second substrate 2 close to the first substrate 1 is provided with a second orientation layer (not shown in the figure). The blue phase liquid crystal layer 3 comprises a liquid crystal and polymer mixed layer, Figure 1 The evolution process of the liquid crystal and polymer mixed layer is also schematically shown: the nanometer scale rod-shaped liquid crystal molecules 31 in the liquid crystal and polymer mixed layer form tens of nanometer scale double helix twisted prisms 32 under the induction of the chiral strength of the material system, and the polarization information of the modulated light field depends on the chirality of the double helix twisted prisms; the double helix twisted prisms 32 are three-dimensionally stacked to form a hundred nanometer scale cubic lattice structure, wherein the cubic lattice structure comprises a body-centered cubic structure 33 or a simple cubic structure 34, corresponding to a blue phase I state and a blue phase II state respectively, and the lattice constant of the cubic lattice structure is positively correlated with the reflection center wavelength of the modulated light field; the first orientation layer and the second orientation layer comprise preset planar arrangement orientation patterns, the orientation patterns induce the cubic lattice structure to self-assemble according to the preset orientation, and the geometric phase of the modulated light field is in a two-fold linear relationship with the loaded in-plane orientation information; when an alternating current electric field perpendicular to the first substrate 1 is applied between the first electrode layer and the second electrode layer, the arrangement order degree of the cubic lattice structure of the liquid crystal and polymer mixed layer increases in combination with the influence of the temperature and the first orientation layer and the second orientation layer, and a blue phase liquid crystal single domain is formed; the liquid crystal and polymer mixed layer form a patterned single-domain blue phase liquid crystal which stably exists at room temperature.

[0050] The first substrate 1 and the second substrate 2 can be a flexible substrate or a rigid substrate with high light transmission efficiency (greater than or equal to 85%). For example, the material of the first substrate 1 and the second substrate 2 can include quartz glass or ordinary glass. The first electrode layer and the second electrode layer are transparent electrodes, for example, electrodes formed of indium tin oxide (ITO). In a specific implementation, the first electrode layer can be located on the side of the first substrate 1 close to the second substrate 2 or between the first substrate 1 and the first orientation layer; the second electrode layer can be located on the side of the second substrate 2 close to the first substrate 1 or between the second substrate 2 and the second orientation layer, which can be selected according to actual conditions in a specific implementation. In a specific implementation, spacer particles can also be arranged at the edge positions of the first substrate 1 and the second substrate 2, and the spacer particles are used to support the first substrate 1 and the second substrate 2 and control the thickness of the blue phase liquid crystal layer 3. Optionally, the spacer particles include at least one of quartz microspheres and quartz columns, and the longitudinal dimension of the spacer particles is greater than or equal to 10 times the cubic lattice constant in the liquid crystal and polymer mixed layer in a direction perpendicular to the first substrate 1, so as to improve the Bragg diffraction efficiency of the single-domain blue phase liquid crystal and improve the performance of the optical device. The first orientation layer and the second orientation layer have a planar anchoring effect on the cubic lattice structure in the liquid crystal and polymer mixed layer. The corresponding orientation layer pattern can be designed as needed to make the in-plane azimuth angle of the cubic lattice structure on the surface consistent with the orientation direction, so as to endow the optical device with functions such as wide-viewing-angle polarization selection grating and full-color holographic imaging. An alternating current electric field perpendicular to the first substrate 1 is applied between the first electrode layer and the second electrode layer, and the nucleation condition in the slow cooling process and the surface anchoring condition of the first orientation layer and the second orientation layer are combined, so that the arrangement order of the cubic lattice structure of the liquid crystal and polymer mixed layer increases, and a patterned blue phase liquid crystal single domain is formed. After the patterned blue phase liquid crystal single domain is formed, the liquid crystal and polymer mixed layer are polymerized by using ultraviolet light, so as to form a stable patterned single-domain blue phase liquid crystal at room temperature.

[0051] The technical scheme of the embodiment of the present application flexibly controls the multi-level and cross-scale structure, systematically realizes efficient modulation of blue phase liquid crystal on the polarization, wavelength, phase and intensity of the light field, provides the feasibility of optical multi-dimensional independent control, and can be applied to the fields of optical computing, optical communication, high-spectral imaging, color holographic display and the like, and further promotes the development of existing optical systems. Moreover, compared with the optical device in the prior art, the single-domain blue phase liquid crystal used to prepare the light field multi-dimensional modulation device has higher color saturation, a wider viewing angle, can realize omnidirectional, multi-dimensional and tunable light field modulation, and has the advantages of simple preparation process, low cost, erasable and reconfigurable multi-functional multiplexing effect.

[0052] Optionally, the spatial chirality of the double-helical twist prisms determines the polarization of the modulated light field, light with the same chirality as the double-helical twist prisms is reflected, and light with the opposite chirality is transmitted; the lattice constant of the cubic lattice structure determines the wavelength of the modulated light field, and the lattice constant of the cubic lattice structure is controlled by controlling the material ratio and / or external conditions to adjust the wavelength of the reflection center, wherein the larger the lattice constant of the cubic lattice structure, the longer the wavelength of the modulated light field; the crystal plane orientation of the cubic lattice structure determines the phase of the modulated light field, and the crystal plane orientation of the cubic lattice structure is controlled by external conditions to modulate the phase of the reflected light.

[0053] The external conditions include an electric field, a light field, or a temperature adjustment. By applying an electric field, a light field, or adjusting the temperature of the device, the response of the device to different light fields can be changed. Specifically, the initial chirality of the double-helical twist prisms depends on the chirality of the chiral agent incorporated in the liquid crystal and polymer mixed layer, and a suitable chiral agent material can be selected according to the required polarization conditions of the modulated light field; in addition, the direction of the chirality of the system can be controlled by light, heat, and other modulation means. The lattice constant of the nanometer-scale cubic lattice structure depends on the concentration of the chiral agent incorporated in the liquid crystal and polymer mixed layer, and the cubic lattice constant is negatively related to the concentration of the incorporated chiral agent; the cubic lattice constant can be changed by multi-external-condition modulation means such as electricity, light, heat, etc., thereby realizing the wavelength adjustment of the reflection center of the device. The range of the single-domain blue-phase liquid crystal grain boundary can be finely controlled by external conditions to control the uniformity of the liquid crystal and polymer mixed layer, thereby realizing the amplitude modulation effect of the light field.

[0054] Optionally, the liquid crystal and polymer mixed layer includes nematic liquid crystal, chiral agent, polymer monomer, and photoinitiator.

[0055] Optionally, the first alignment layer and the second alignment layer include at least one of photo-crosslinking material, photo-degradation material, and photo-isomerization material, the control pattern of the first alignment layer and the second alignment layer is erasable, and the thickness of the alignment layer ranges from 30 nm to 50 nm. The first alignment layer and the second alignment layer induce the cubic lattice structure of the blue-phase liquid crystal layer to self-assemble according to the preset orientation from the upper and lower surfaces, respectively; the control pattern of the first alignment layer and the second alignment layer is erasable, the function of the optical device can be changed by changing the preset pattern, and the integration of the multifunctional optical device is realized.

[0056] Figure 2 The orthogonal polarizing microscope contrast diagram of the light-controlled alignment and the unaligned blue-phase liquid crystal domain state in the embodiments of the present application is shown in the following figure. Figure 2, wherein R1, B1, G1 are polarizing microscope images of red, blue, green blue phase liquid crystals under non-oriented condition respectively, R2, B2, G2 are polarizing microscope images of red, blue, green blue phase liquid crystals under photo-aligned condition respectively, and the small insets in the lower right corner are Kossel diffraction patterns in each state. The comparison of polarizing microscope images of the sample without orientation and the sample under photo-aligned condition shows that the surface anchoring condition plays a crucial role in the formation of single domain. The Kossel diffraction patterns of the red and blue single-domain blue phase liquid crystals (the insets in the lower right corner of R2 and B2) correspond to the crystal faces of the blue phase I state and the blue phase II state respectively, and the clear and obvious Kossel diffraction patterns also prove the ideality of the single-domain growth. However, the green blue phase liquid crystal corresponds to the blue phase I state, which is obtained by phase transition from the blue phase II state in a slow cooling process, and forms a multi-domain structure with non-uniform crystal face orientation.

[0057] Figure 3 It is a polarizing microscope image of the green single-domain blue phase liquid crystal prepared by the method in the embodiment of the present application. Referring to Figure 3 , wherein 1, 2, and 3 are the green multi-domain blue phase liquid crystal before power-on, the liquid crystal molecules in a vertical alignment arrangement state during power-on, and the green single-domain blue phase liquid crystal after power-on respectively. An alternating current electric field perpendicular to the first substrate and the second substrate is applied through the first electrode layer and the second electrode layer, so that the positive liquid crystal molecules are arranged along the direction of the electric field to achieve the vertical alignment arrangement state; after the power is turned off, the liquid crystal directly phase transitions from the vertical alignment arrangement state to the blue phase I state, thereby realizing the self-assembly process of the green single-domain blue phase liquid crystal induced by the surface anchoring and uniform nucleation.

[0058] Figure 4 It is a schematic diagram of the reflection spectrum of the red, green, and blue single-domain blue phase liquid crystals. Referring to Figure 4 , the reflection center wavelength of the red single-domain blue phase liquid crystal is 625 nm, and the bandwidth is 20 nm; the reflection center wavelength of the green single-domain blue phase liquid crystal is 543 nm, and the bandwidth is 14 nm; and the reflection center wavelength of the blue single-domain blue phase liquid crystal is 462 nm, and the bandwidth is 18 nm. The size of the reflection center wavelength is positively correlated with the lattice constant, and the lattice constants of the red, green, and blue single-domain blue phase liquid crystals decrease in turn.

[0059] Figure 5 It is a schematic diagram of the temperature rising and falling test of the blue, green, and red three-color samples after the single-domain blue phase liquid crystal is subjected to the operation of polymer stabilization. Referring to Figure 5 , during the temperature change from 20℃ to 38℃, the reflection center wavelengths and the reflection band half-widths of the blue, green, and red three-color samples fluctuate very little, which indicates that the blue, green, and red three-color samples maintain good single-domain characteristics during the temperature change, and can effectively realize the single-domain blue phase liquid crystal that stably exists at room temperature.

[0060] For example, the optical field multi-dimensional modulation device provided in this embodiment of the invention can realize the function of a wide-viewing-angle polarization-selective grating. Under wide-viewing-angle conditions, this optical field multi-dimensional modulation device can still maintain good polarization selection characteristics, and has many applications in virtual / augmented reality, autonomous driving, intelligent vehicle lighting and other fields.

[0061] Figure 6 This is a schematic diagram of the liquid crystal director distribution of the wide-viewing-angle polarization-selective grating and an orthogonal polarizing microscope image of the sample in an embodiment of the present invention. (Reference) Figure 6 The direction of the liquid crystal pointing vector of the optical device is periodically and gradually distributed. For example, the period is set to 40 μm. In each period, the direction of the liquid crystal pointing vector gradually changes from 0° to 180°. In the figure, the change from dark to bright indicates that the direction of the liquid crystal pointing vector gradually changes from 0° to 180°. The cross-polarized light microscope image shows that the optical device achieves the effect of ideal patterned single-domain blue phase liquid crystal.

[0062] Figure 7 This is a schematic diagram of the diffraction optical path of the wide-view polarization-selective grating in an embodiment of the present invention. (Reference) Figure 7 The optical path includes a laser 10, a linear polarizer 20, a quarter-wave plate 30, a multi-dimensional optical field modulator 40, and a CCD or receiving screen 50 located in the direction of the reflected light after passing through the multi-dimensional optical field modulator 40, arranged sequentially along the optical axis. The beam output from the laser 10 passes through the linear polarizer 20 and the quarter-wave plate 30 in sequence before being incident on the multi-dimensional optical field modulator 40. The light reflected by the multi-dimensional optical field modulator 40 is received by the CCD or receiving screen 50. To facilitate consideration of its wide-angle polarization selectivity characteristics, a displacement stage is added under the sample holder for rotation operation, where α is the deflection angle of the multi-dimensional optical field modulator 40.

[0063] Figure 8This embodiment shows the diffraction patterns of a wide-viewing-angle polarization-selective grating incident at different angles and polarization states. The diffraction patterns correspond to increasing α from left to right, with the Bragg reflection center wavelength decreasing sequentially from 625 nm to 575 nm to 545 nm, satisfying the inverse proportionality relationship between the reflection center wavelength and the incident angle within the range of 0° to 90°. Comparing the upper and lower rows of the diffraction patterns reveals that a diffraction pattern exists when the incident light rotation is consistent with the chiral agent rotation; no diffraction pattern exists when their rotations are opposite; and the polarization selectivity remains good during angle changes. Therefore, the multi-dimensional optical field modulation device provided in this embodiment effectively combines the beam deflection capability of the grating with the wide-viewing-angle polarization selectivity capability of the blue phase liquid crystal. Furthermore, the polarization state and reflection center wavelength of the modulated light field can be changed by adjusting the chiral agent rotation and concentration, achieving a multi-functional, multiplexed multi-dimensional optical field modulation device. Multidimensional optical field modulation devices can replace a collection of traditional optical components in an optical path system and can be applied in fields such as virtual / augmented reality, autonomous driving, and smart car lights. They have advantages such as high efficiency, high flexibility, miniaturization, and integration.

[0064] For example, this embodiment of the invention provides an application based on the above-mentioned multi-dimensional light field modulation device. According to color classification, phase information is loaded into different regions of blue phase liquid crystal samples of different colors through light-controlled orientation. By changing the position, pseudo-dynamic switching RGB color holographic display can be achieved.

[0065] In one embodiment of the present invention, a color holographic display is achieved through a layering method. Even when complex orientation information is applied to the multi-dimensional light field modulation device, the device still exhibits geometric phase diffraction effects. Simultaneously, by adjusting the concentration and rotation of the chiral agent, modulated light fields of different colors and polarization states can be obtained, exhibiting high color saturation and good polarization selectivity. This allows it to be used as a multi-dimensional light field modulation device in fields such as holographic display and hyperspectral imaging.

[0066] Figure 9 These are design diagrams of two full-color holograms in an embodiment of the present invention. (Reference) Figure 9 Both design drawings contain three components: red, green, and blue. Figure 9 In Figure 1, the flower buds are red, the stems are green, and the pot is blue. In Figure 2, the five-petaled flower is red, the stems and leaves are green, and the butterfly is blue. The phase information of the diffraction surface is calculated from the design drawing using an algorithm. The liquid crystal orientation distribution is derived from geometric phase theory. The phase information is then loaded into different regions of different blue phase liquid crystal samples according to the three colors of red, green, and blue through light orientation.

[0067] Figure 10 These are orthogonal polarizing microscope (POM) images and diffraction patterns of different regions of blue phase liquid crystal samples of different colors in embodiments of the present invention. (Reference) Figure 10As shown in the crossed polarized light microscope images, even with the addition of more complex phase information, the blue phase single domains still maintain an ideal state, ensuring the maximization of subsequent diffraction efficiency. The scale bar in the image is 200 μm. Figure 10 In the diagram, 1, 2, and 3 represent the diffraction patterns corresponding to the red, green, and blue components of the first design drawing, respectively, while 4, 5, and 6 represent the diffraction patterns corresponding to the red, green, and blue components of the second design drawing.

[0068] Figure 11 This is a diffraction effect diagram of different regions of blue phase liquid crystal samples of different colors stacked in an embodiment of the present invention. (Reference) Figure 11 , Figure 10 The numbers 1, 2, and 3 can form... Figure 11 The "budding" pattern shown in Figure 7 can be formed by combining 1, 5, and 3. Figure 11 The "lush foliage" pattern shown in number 8 can be formed by numbers 4, 5, and 6. Figure 11 The "flowers and butterflies dancing" pattern shown in Figure 9 illustrates the process of flowers blooming in a gradual manner. Figure 10 , 11 The numbers 1 through 9 represent the diffraction patterns displayed on the receiving screen. The diffraction results largely match the designed pattern, and the diffraction efficiency remains considerable even after reflection through multiple layers of glass, exhibiting high color saturation. Therefore, this multi-dimensional light field modulation device can achieve pseudo-dynamic switching of color holographic display by changing its position. Combined with multi-field external control techniques, multi-dimensional light field modulation optical devices with dynamically adjustable reflection center wavelength, polarization state, and phase information can be fabricated. These devices possess advantages such as high color saturation, high light energy utilization, and erasable rewriteability, opening up new possibilities for fields such as color holographic display and hyperspectral imaging.

[0069] Figure 12 This invention provides a method for fabricating a multi-dimensional optical field modulation device, which is used to fabricate the aforementioned multi-dimensional optical field modulation device. (Refer to...) Figure 12 The preparation method includes:

[0070] Step S110: Provide a first substrate and a second substrate.

[0071] The first substrate and the second substrate can be flexible substrates or rigid substrates with high light transmittance (greater than or equal to 85%). For example, the substrate material can include quartz glass or ordinary glass.

[0072] Step S120: A first electrode layer is formed on one side of the first substrate, a first alignment layer is formed on the side of the first substrate near the second substrate, a second electrode layer is formed on one side of the second substrate, and a second alignment layer is formed on the side of the second substrate near the first substrate.

[0073] The first electrode layer can be located on the side of the first substrate close to the second substrate or between the first substrate and the first alignment layer; the second electrode layer can be located on the side of the second substrate close to the first substrate or between the second substrate and the second alignment layer, which can be selected according to actual conditions in implementation, and the first electrode layer and the second electrode layer can be made of an indium tin oxide film. The material of the first alignment layer and the second alignment layer includes at least one of a photo-crosslinking material, a photo-degradation material and a photo-induced cis-trans isomerization material. Optionally, the material of the first alignment layer and the second alignment layer is an acid azo dye 4,4'-di(4-hydroxy-3-carboxy-phenylazo) benzidine-2,2'-disulfonic acid. Before spin-coating the first alignment layer and the second alignment layer, in order to increase the wettability and adhesion of the alignment layer to the substrate, the substrate is first cleaned with an ITO (indium tin oxide film) cleaning solution for 20 minutes, and then cleaned with ultrapure water twice for 10 minutes each time; after cleaning, the water stains on the surface of the substrate are blown off with an air gun, and then the substrate is placed in a 120℃ oven for drying for 40 minutes, and finally UVO (ultraviolet ozone) cleaning is performed.

[0074] Optionally, the formation of the alignment layer on the side of the first substrate close to the second substrate and the side of the second substrate close to the first substrate can be performed in the following manner: the photo-controlled alignment material acid azo dye 4,4'-di(4-hydroxy-3-carboxy-phenylazo) benzidine-2,2'-disulfonic acid is spin-coated on the side of the substrate close to the liquid crystal, and the spin-coating parameters are: low rotation speed 800 rpm for 5 seconds; high rotation speed 3000 rpm for 40 seconds; after spin-coating, the substrate is placed on a hot stage at 100℃ for annealing for 10 minutes to form a photo-controlled alignment layer with a thickness in the range of 30nm-50nm.

[0075] Step S130, packaging the first substrate and the second substrate.

[0076] The packaging of the first substrate and the second substrate can include: arranging spacer particles between the first substrate and the second substrate to support the first substrate and the second substrate and form a filling space of the liquid crystal and polymer mixed layer. The spacer particles include at least one of quartz microspheres and quartz columns, and the longitudinal dimension of the spacer particles is greater than or equal to 10 times the cubic lattice constant in the liquid crystal and polymer mixed layer in the direction perpendicular to the first substrate. Optionally, the spacer particles are mixed into ultraviolet curing glue and coated in a small amount on the inner side edge of the substrate, and after the first substrate and the second substrate are aligned and boxed, ultraviolet light curing is performed.

[0077] Step S140, filling the liquid crystal and polymer mixed layer in the isotropic phase between the first substrate and the second substrate.

[0078] The first alignment layer and the second alignment layer have a control pattern of liquid crystal molecule director distribution, under the joint action of the first alignment layer and the second alignment layer, the cubic lattice structure composed of double helix structure columns in the liquid crystal and polymer mixed layer is induced to self-assemble according to a preset orientation. The liquid crystal and polymer mixed layer comprises nematic liquid crystal, chiral agent, polymer monomer and photoinitiator.

[0079] In step S150, the packaged device is placed on a hot stage, and the temperature is changed to make the liquid crystal and polymer mixed layer undergo a phase transition process from isotropic phase to blue phase II to blue phase I or isotropic to blue phase I.

[0080] In specific implementation, the hot stage is controlled to slowly cool to cause the liquid crystal phase transition, and the specific temperature can be set according to actual conditions.

[0081] In step S160, an alternating current electric field perpendicular to the first substrate is applied between the first electrode layer and the second electrode layer, and the cubic lattice structure of the liquid crystal and polymer mixed layer has an increased ordered degree of arrangement under the influence of the temperature and the first alignment layer and the second alignment layer, to form a blue phase liquid crystal single domain structure.

[0082] The light field multi-dimensional modulation device prepared by the embodiment of the present application has higher color saturation and a wider field of view than the optical device in the prior art, can realize omnidirectional, multi-dimensional and tunable light field modulation, has a simple preparation process, low cost, and can realize multi-functional multiplexing effect through erasing and rewriting.

[0083] Optionally, after the liquid crystal and polymer mixed layer is poured between the first substrate and the second substrate, a method of ultraviolet polymerization is used to obtain a stable single-domain blue phase liquid crystal at room temperature.

[0084] The above specific implementation does not constitute a limitation on the protection scope of the present application. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent replacement and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. An optical field multi-dimension modulating device, characterized in that, For independently modulating polarization, wavelength and phase information of light field; comprising: Oppositely arranged first substrate, second substrate and blue phase liquid crystal layer between the first substrate and the second substrate; The first substrate is provided with a first electrode layer on one side, the first substrate is provided with a first orientation layer on the side close to the second substrate, the second substrate is provided with a second electrode layer on one side, and the second substrate is provided with a second orientation layer on the side close to the first substrate; The blue phase liquid crystal layer comprises a liquid crystal and polymer mixed layer, and the nanometer scale rod-shaped liquid crystal molecules in the liquid crystal and polymer mixed layer form tens of nanometer scale double helix twisted prisms under the induction of the chiral strength of the material system; The double helix twisted prisms are three-dimensionally stacked to form a hundred nanometer scale cubic lattice structure; The first orientation layer and the second orientation layer comprise a preset planar arrangement orientation pattern, and the orientation pattern induces the cubic lattice structure to self-assemble according to the preset orientation; Wherein, the spatial rotation of the double helix twisted prism determines the polarization of the modulated light field, and the light matching the rotation of the double helix twisted prism is reflected, and the light opposite to the rotation of the double helix twisted prism is transmitted; The lattice constant of the cubic lattice structure determines the wavelength of the modulated light field, and the lattice constant of the cubic lattice structure is controlled by controlling the material ratio and / or external conditions to adjust the wavelength of the reflection center. The larger the lattice constant of the cubic lattice structure, the longer the wavelength of the modulated light field; The crystal face orientation of the cubic lattice structure determines the phase of the modulated light field, and the crystal face orientation of the cubic lattice structure is controlled by external conditions to modulate the phase of the reflected light.

2. The light field multi-dimensional modulation device of claim 1, wherein, The initial rotation of the double helix twisted prism is determined by the chirality of the chiral agent doped in the liquid crystal and polymer mixed layer; and the initial lattice constant of the cubic lattice is determined by the concentration of the chiral agent doped in the liquid crystal and polymer mixed layer.

3. The light field multi-dimensional modulation device of claim 1, wherein, The structure uniformity of the liquid crystal and polymer mixed layer is controlled by external conditions to control the blue phase liquid crystal grain boundary range to modulate the amplitude of the light field.

4. The light field multi-dimensional modulation device according to claim 1 or 3, characterized in that, The external conditions include electric field, light field or adjusting temperature.

5. The light field multi-dimensional modulation device of claim 1, wherein, The liquid crystal and polymer mixed layer comprises nematic liquid crystal, chiral agent, polymer monomer and photoinitiator.

6. The light field multi-dimensional modulation device of claim 1, wherein, The first electrode layer is located on the side of the first substrate close to the second substrate or between the first substrate and the first orientation layer; The second electrode layer is located on the side of the second substrate close to the first substrate or between the second substrate and the second orientation layer.

7. The light field multi-dimensional modulation device of claim 1, wherein, Further comprising spacer particles between the first substrate and the second substrate, the spacer particles comprising at least one of quartz microspheres and quartz columns.

8. The light field multi-dimensional modulation device of claim 1, wherein, The first orientation layer and the second orientation layer comprise at least one of photo-crosslinking material, photo-degradation material and photo-induced cis-trans isomerization material, the control pattern of the first orientation layer and the second orientation layer can be erased, and the thickness of the orientation layer ranges from 30nm to 50nm.

9. A method for producing an optical field multidimensional modulation device, for producing the optical field multidimensional modulation device according to any one of claims 1 to 8, characterized by, Comprising: Providing a first substrate and a second substrate; forming a first electrode layer on one side of the first substrate, forming a first orientation layer on the side of the first substrate close to the second substrate, forming a second electrode layer on one side of the second substrate, and forming a second orientation layer on the side of the second substrate close to the first substrate; encapsulating the first substrate and the second substrate; filling a liquid crystal and polymer mixed layer in an isotropic phase between the first substrate and the second substrate; wherein the first orientation layer and the second orientation layer have a control pattern of liquid crystal molecule director distribution, and under the joint action of the first orientation layer and the second orientation layer, the cubic lattice structure composed of double helix structure columns in the liquid crystal and polymer mixed layer is induced to self-assemble according to a preset orientation; placing the encapsulated device on a hot stage, changing the temperature to make the liquid crystal and polymer mixed layer undergo a phase transition process from an isotropic phase to a blue phase II to a blue phase I or from an isotropic phase to a blue phase I; applying an alternating electric field perpendicular to the first substrate between the first electrode layer and the second electrode layer, and combining the temperature with the influence of the first orientation layer and the second orientation layer, the order degree of the cubic lattice structure arrangement of the liquid crystal and polymer mixed layer is increased to form a blue phase liquid crystal single domain structure.

10. The method of claim 9, wherein, After filling the liquid crystal and polymer mixed layer between the first substrate and the second substrate, a method of ultraviolet polymerization is used to obtain a stable single-domain blue phase liquid crystal at room temperature.

11. Use of the light field multi-dimensional modulation device according to any one of claims 1 to 8, characterized in that, According to the color classification, phase information is loaded into different regions of different color blue phase liquid crystal samples by light-controlled orientation, and by changing the position, pseudo-dynamic switching RGB color holographic display can be realized.

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