All-solid-state H-PDLC volume holographic grating and preparation method thereof

Abstract

The invention provides an all-solid-state H-PDLC volume holographic grating and a preparation method thereof.The all-solid-state H-PDLC volume holographic grating comprises a plurality of periodic structures and liquid crystal macromolecules located between the adjacent periodic structures, the liquid crystal macromolecules are formed by polymerizing liquid crystal polymerizable monomers, the periodic structures are non-liquid crystal macromolecules, and the periodic structures are non-liquid crystal macromolecules. The liquid crystal polymer is formed by polymerizing non-liquid crystal polymerizable monomers. According to the preparation method, the liquid crystal macromolecules are adopted to replace small-molecule liquid crystals in common H-PDLC, and the all-solid-state substrate-free H-PDLC can be prepared, so that the size of a device is effectively reduced, and the influence of the substrate on the optical property of the device is avoided.

Description

Technical Field

[0001] The present application relates to the technical field of grating structures, and in particular to an all-solid-state H-PDLC volume holographic grating and a preparation method thereof. Background Art

[0002] Diffraction grating is a diffraction optical element with periodic spatial structure or optical properties. It has amplitude and phase modulation effect on the incident light wave. Its main function is to realize the spatial separation of complex light. It has been widely used in many fields such as spectral instruments, astronomy, metrology, integrated optics, information processing, optical communication and high-power laser systems. From the perspective of grating spectroscopic properties, it can be divided into thin grating (surface grating) and volume grating. The incident energy of the former is distributed on all levels of diffraction peaks, while the incident energy of the latter is mainly concentrated on the first-order diffraction peak (theoretical first-order diffraction efficiency can reach 100%). Therefore, volume grating has great advantages and potential in scenarios requiring high diffraction efficiency. At present, the material systems for preparing volume gratings mainly include H-PDLC (holographic polymer dispersed liquid crystal), photopolymer, silver halide and dichromate. However, the refractive index modulation of the three systems of photopolymer, silver halide and dichromate is small (generally below 0.05), which is not conducive to the improvement of the grating field of view (FOV). The high refractive index modulation of H-PDLC (up to 0.1-0.3) makes it the best choice for high FOV gratings. H-PDLC is composed of polymers and small molecule liquid crystals alternating in a stacked structure. The liquid fluidity of small molecule liquid crystals determines that it must use upper and lower substrates to form a sealed structure during its preparation and use, which undoubtedly increases the size of the device and inevitably brings unnecessary effects on the optical properties of the device. Summary of the invention

[0003] The purpose of this application is to provide a fully solid H-PDLC volume holographic grating and a preparation method thereof, which uses liquid crystal polymers to replace small molecule liquid crystals in ordinary H-PDLCs, and can prepare fully solid, substrate-free H-PDLCs, thereby effectively reducing the size of the device and avoiding the influence of the substrate on the optical properties of the device. The specific technical solution is as follows:

[0004] The first aspect of the present application provides an all-solid-state H-PDLC volume holographic grating, comprising a plurality of periodic structures and liquid crystal polymers located between adjacent periodic structures, wherein the liquid crystal polymers are polymerized from liquid crystal polymerizable monomers, and the periodic structures are non-liquid crystal polymers, which are polymerized from non-liquid crystal polymerizable monomers.

[0005] In some embodiments of the present application, the refractive index modulation degree Δn between the liquid crystal polymer and the non-liquid crystal polymer is 0.001-0.5.

[0006] In some embodiments of the present application, the liquid crystal polymer is obtained by polymerization using photopolymerization or thermal polymerization; the non-liquid crystal polymer is obtained by polymerization using photopolymerization.

[0007] The second aspect of the present application provides a method for preparing an all-solid-state H-PDLC volume holographic grating, which comprises the steps of:

[0008] Prepare a liquid crystal slurry, wherein the liquid crystal slurry comprises a liquid crystal polymerizable monomer, a non-liquid crystal polymerizable monomer and an initiator;

[0009] Filling the containing space with the liquid crystal slurry, and then performing interference exposure, so that the non-liquid crystal polymerizable monomer is polymerized to form a plurality of periodic structures composed of non-liquid crystal polymers;

[0010] The liquid crystal slurry containing the non-liquid crystal polymer is irradiated with light or heated to polymerize the liquid crystal polymerizable monomer to form liquid crystal polymers between adjacent periodic structures, thereby obtaining the all-solid-state H-PDLC volume holographic grating.

[0011] In some embodiments of the present application, in the liquid crystal slurry: the content of the liquid crystal polymerizable monomer is 4.5wt%-95wt%, the content of the non-liquid crystal polymerizable monomer is 0.5wt%-95wt%, and the content of the initiator is 0.05wt%-10wt%.

[0012] In some embodiments of the present application, the method for preparing the accommodating space comprises the steps of:

[0013] providing a first substrate and a second substrate;

[0014] forming a first dissociable layer on a surface of the first substrate;

[0015] A sealing glue is formed between the first dissociable layer and the second substrate, and the sealing glue, the first dissociable layer and the second substrate define a receiving space.

[0016] In some embodiments of the present application, after forming the liquid crystal polymer and before obtaining the all-solid-state H-PDLC volume holographic grating, the method further includes: performing a dissociation treatment on the first dissociable layer to peel off the first dissociable layer and the first substrate.

[0017] In some embodiments of the present application, the method for preparing the accommodating space comprises the steps of:

[0018] providing a first substrate and a second substrate;

[0019] forming a first dissociable layer on one surface of the first substrate; and forming a second dissociable layer on a side of the second substrate close to the first dissociable layer;

[0020] A frame sealant is formed between the first dissociable layer and the second dissociable layer, and the frame sealant, the first dissociable layer, and the second dissociable layer define the accommodation space.

[0021] In some embodiments of the present application, after forming the liquid crystal polymer and before obtaining the all-solid-state H-PDLC volume holographic grating, the following steps are further included:

[0022] performing a dissociation process on the first dissociable layer so that the first dissociable layer and the first substrate are peeled off;

[0023] The second dissociable layer is subjected to a dissociation treatment so that the second dissociable layer and the second substrate are peeled off.

[0024] In some embodiments of the present application, the thickness of the first dissociable layer is 30 nm-500 μm; the material forming the first dissociable layer is selected from a mechanical separation material, a laser viscosity reduction material or a UV viscosity reduction material.

[0025] In some embodiments of the present application, the dissociation treatment is mechanical peeling, laser dissociation or UV light irradiation dissociation.

[0026] In some embodiments of the present application, the thickness of the second dissociable layer is 30 nm-500 μm; the material forming the second dissociable layer is selected from a mechanical separation material, a laser viscosity reduction material or a UV viscosity reduction material.

[0027] The third aspect of the present application provides an optical device, comprising the all-solid-state H-PDLC volume holographic grating described in the first aspect of the present application or the all-solid-state H-PDLC volume holographic grating prepared by the method described in the second aspect of the present application.

[0028] Beneficial effects of this application:

[0029] The present application provides an all-solid-state H-PDLC volume holographic grating, which uses liquid crystal polymers to replace small molecule liquid crystals in ordinary H-PDLC. On the basis of retaining the high Δn (refractive index modulation degree) of ordinary H-PDLC, the H-PDLC forms an all-solid-state structure, which can be directly used without a substrate, and can effectively reduce the volume of the device and the optical influence of the substrate on the device; the present application also provides a preparation method of the H-PDLC volume holographic grating, which adds a post-polymerization step on the basis of the conventional H-PDLC preparation steps, so that the liquid crystal polymerizable monomers are polymerized into liquid crystal polymers, and then the substrate is peeled off to obtain the H-PDLC volume holographic grating. The preparation method is simple and has strong operability.

[0030] Of course, implementing any product or method of the present application does not necessarily require achieving all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and a person skilled in the art can also obtain other embodiments based on these drawings.

[0032] Figure 1 A schematic structural diagram of a solid-state H-PDLC volume holographic grating without a substrate according to an embodiment of the present application;

[0033] Figure 2 A schematic structural diagram of a fully solid H-PDLC volume holographic grating having a substrate on only one side according to another embodiment of the present application;

[0034] Figure 3 Schematic diagram for the interference exposure light path;

[0035] Figure 4 A schematic flow chart of a method for preparing a substrate-free all-solid-state H-PDLC volume holographic grating according to an embodiment of the present application;

[0036] Figure 5 A schematic flow chart of a method for preparing a fully solid H-PDLC volume holographic grating having a substrate on only one side according to another embodiment of the present application;

[0037] Figure 6 This is a schematic diagram of multiple all-solid-state H-PDLC volume holographic grating structures prepared simultaneously according to another embodiment of the present application.

[0038] In the figure, 1. all-solid-state H-PDLC volume holographic grating, 11. first (glass) substrate, 12. first debondable layer, 21. second (glass) substrate, 22. second debondable layer, 31. frame sealant, 41. containing space, 51. liquid crystal slurry, 61. non-liquid crystal polymer, 71. liquid crystal polymer, 101. CW laser, 102. shutter, 103. beam expander, 104. beam splitter, 105. reflector, 106. sample stage. DETAILED DESCRIPTION

[0039] The following will be combined with the embodiments of the present application and the accompanying drawings to clearly and completely describe the technical solutions in the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those skilled in the art based on the present application belong to the scope of protection of the present application.

[0040] The current H-PDLC is composed of a stacked structure of alternating polymers and small molecule liquid crystals. The liquid fluidity of small molecule liquid crystals determines that upper and lower substrates must be used to form a sealed structure during its preparation and use, which increases the volume of the device, makes the device structure complicated, and inevitably brings unnecessary effects on the optical properties of the device.

[0041] The applicant found in the research that one of the major characteristics of H-PDLC is that its diffraction efficiency can be regulated by electric field. In many applications, such as the coupling-in and coupling-out gratings of AR devices, only its large Δn (refractive index modulation) characteristic is required, and its electrical regulation function is not required. Therefore, liquid crystal polymers can be considered to replace small molecule liquid crystals. Liquid crystal polymers retain the large Δn characteristics of small molecule liquid crystals, so the original large Δn characteristics of H-PDLC will not be affected.

[0042] The first aspect of the present application provides an all-solid-state H-PDLC volume holographic grating, comprising a plurality of periodic structures and liquid crystal polymers located between adjacent periodic structures, wherein the liquid crystal polymers are polymerized from liquid crystal polymerizable monomers, and the periodic structures are non-liquid crystal polymers, which are polymerized from non-liquid crystal polymerizable monomers.

[0043] In one embodiment of the present application, Figure 1 As shown, the substrate-free all-solid H-PDLC volume holographic grating 1 includes: a periodic structure formed by a plurality of non-liquid crystal polymers 61 and liquid crystal polymers 71 located between adjacent periodic structures.

[0044] In one embodiment of the present application, Figure 2 As shown, the all-solid-state H-PDLC volume holographic grating 1 having a substrate on only one side includes: a periodic structure formed by a plurality of non-liquid crystal polymers 61, liquid crystal polymers 71 located between adjacent periodic structures, and a substrate 21, wherein the periodic structure formed by a plurality of non-liquid crystal polymers 61 and the liquid crystal polymers 71 located between adjacent periodic structures are located on one side of the substrate 21.

[0045] In one embodiment of the present application, Figure 2 As shown, the all-solid-state H-PDLC volume holographic grating 1 having a substrate on only one side further includes a sealing glue 31, wherein the sealing glue 31 is located on one side of the substrate 21, and the sealing glue 31 and the substrate 21 form a semi-enclosed space, and a periodic structure formed by a plurality of non-liquid crystal polymers 61 and liquid crystal polymers 71 located between adjacent periodic structures are filled in the semi-enclosed space.

[0046] The present application has no particular limitation on the type of liquid crystal polymerizable monomer, as long as the purpose of the present application can be achieved and photopolymerization or thermal polymerization can occur. For example, the liquid crystal polymerizable monomer can be selected from liquid crystal epoxy resin or liquid crystal acrylate polymerizable monomer; the liquid crystal acrylate polymerizable monomer includes at least one of the compound represented by formula (I) and the compound represented by formula (II);

[0047]

[0048] A4, A5 and G4 are each independently selected from C1-C 16 Alkylene, C1-C 16 Alkyleneoxy or C1-C 16 Siloxane group;

[0049] G5 is selected from C1-C 16 Alkyl, C1-C 16 Alkoxy or C1-C 16 Siloxane group;

[0050] D4, D5, E4 and E5 are each independently selected from -C(O)O-, -C≡C-, -CH2-, -N=N-, -CH2-O-CH2- or a chemical bond;

[0051] R1, R2 and R3 are each independently selected from acrylate groups;

[0052] J4, J5, L4, L5, M4 and M5 are each independently selected from C6-C 18 Aromatic ring, C6-C 18 Aromatic heterocyclic ring, C3-C 18 Aliphatic heterocyclic or C3-C 18 Aliphatic ring; among them, C6-C 18 Aromatic heterocyclic and C3-C 18 The heteroatoms in the aliphatic ring are each independently selected from N, O or S;

[0053] x4, x5, y4, y5, z4 and z5 are each independently selected from any integer from 0 to 4;

[0054] Q4, Q5, R4, R5, T4 and T5 are each independently selected from halogen, cyano, methyl or methoxy;

[0055] k4, k5, m4, m5, n4 and n5 are each independently selected from any integer from 0-4.

[0056] The present application does not particularly limit the type of non-liquid crystal polymerizable monomers, as long as the invention purpose of the present application can be achieved, and photopolymerization can occur, for example, it can be selected from non-liquid crystal acrylate polymerizable monomers or epoxy resins. The non-liquid crystal acrylate polymerizable monomers include at least one of unsaturated polyesters, polyurethane acrylates, polyester acrylates, polyene thiol systems, polyether acrylates, water-based acrylates and vinyl ethers. The present application does not particularly limit the specific types of unsaturated polyesters, polyurethane acrylates, polyester acrylates, polyene thiol systems, polyether acrylates, water-based acrylates and vinyl ethers, as long as the invention purpose of the present application can be achieved, for example, pentaerythritol tetraacrylate, etc., which can be purchased through commercial channels.

[0057] In some embodiments of the present application, the refractive index modulation degree Δn between the liquid crystal polymer and the non-liquid crystal polymer is 0.001-0.5. In some embodiments of the present application, the refractive index modulation degree Δn between the liquid crystal polymer and the non-liquid crystal polymer can be 0.001, 0.005, 0.01, 0.05, 0.1, 0.2, 0.5 or a range consisting of any two values ​​therebetween.

[0058] In some embodiments of the present application, the liquid crystal polymer is obtained by polymerization using photopolymerization or thermal polymerization; the non-liquid crystal polymer is obtained by polymerization using photopolymerization.

[0059] According to the properties of the liquid crystal polymerizable monomer, the present application specifically selects to use a photoinitiator or a thermal polymerization initiator to initiate the polymerization of the liquid crystal polymerizable monomer to form a liquid crystal polymer; and uses a photoinitiator to initiate the polymerization of the non-liquid crystal polymerizable monomer to form a liquid crystal polymer. For liquid crystal polymerizable monomers such as liquid crystal epoxy resins, an anionic initiator or a cationic initiator can be selected to initiate the polymerization of the liquid crystal epoxy resin to form a liquid crystal polymer.

[0060] The second aspect of the present application provides a method for preparing an all-solid-state H-PDLC volume holographic grating, comprising the steps of:

[0061] Prepare a liquid crystal slurry, wherein the liquid crystal slurry comprises a liquid crystal polymerizable monomer, a non-liquid crystal polymerizable monomer and an initiator;

[0062] Filling the containing space with the liquid crystal slurry, and then performing interference exposure, so that the non-liquid crystal polymerizable monomer is polymerized to form a plurality of periodic structures composed of non-liquid crystal polymers;

[0063] The liquid crystal slurry containing the non-liquid crystal polymer is irradiated with light or heated to polymerize the liquid crystal polymerizable monomer to form liquid crystal polymers between adjacent periodic structures, thereby obtaining the all-solid-state H-PDLC volume holographic grating.

[0064] The liquid crystal slurry of the present application is prepared by uniformly mixing a liquid crystal polymerizable monomer, a non-liquid crystal polymerizable monomer and an initiator.

[0065] The present application specifically selects a photoinitiator or a thermal polymerization initiator to initiate polymerization of the liquid crystal polymerizable monomer to form a liquid crystal polymer according to the properties of the liquid crystal polymerizable monomer; and a photoinitiator to initiate polymerization of the non-liquid crystal polymerizable monomer to form a non-liquid crystal polymer. If a photoinitiator is selected, the liquid crystal slurry containing the non-liquid crystal polymer is irradiated with light during the preparation process; if a thermal polymerization initiator is selected, the liquid crystal slurry containing the non-liquid crystal polymer is heated during the preparation process.

[0066] If a photoinitiator is used to initiate polymerization of liquid crystal polymerizable monomers to form liquid crystal polymers, the photoinitiator used in the present application can initiate polymerization of liquid crystal polymerizable monomers and non-liquid crystal polymerizable monomers at the same or different wavelengths. The present application does not particularly limit the specific type of the photoinitiator, as long as the purpose of the present application can be achieved, and it can include one or more photoinitiators, such as N-phenylglycine ethyl ester (N-phenylglycine) and Rose Bengal (CAS NO.: 632-69-9).

[0067] If a thermal polymerization initiator is used to initiate polymerization of liquid crystal polymerizable monomers to form liquid crystal polymers, the photoinitiator used in this application can initiate polymerization of non-liquid crystal polymerizable monomers. This application does not specifically limit the specific types of photoinitiators and thermal polymerization initiators, as long as the purpose of this application can be achieved.

[0068] The present application does not have any particular restrictions on the specific method of using liquid crystal slurry to fill the receiving space, as long as the purpose of the invention of the present application can be achieved, for example, using VAS (Vacuum Align System), vacuum infusion process or capillary action to fill the liquid crystal slurry into the receiving space.

[0069] The interference exposure optical path of this application is constructed as follows Figure 3As shown: It is mainly composed of CW laser 101, shutter 102, beam expander 103, beam splitter 104, reflector 105, and sample stage 106. The angle of the interference beam is determined by the parameters of the grating to be prepared. The exposure laser wavelength is determined by the absorption wavelength range of the photoinitiator of the non-liquid crystal polymerizable monomer. Since the polymerization rate of the non-liquid crystal polymerizable monomer is faster than that of the liquid crystal polymerizable monomer, the non-liquid crystal polymerizable monomer can be polymerized to form a general H-PDLC by controlling the light power density and the illumination time, while the liquid crystal polymerizable monomer does not polymerize (or basically does not). The direction of the grating period is perpendicular to the direction of the angle bisector of the two interference beams.

[0070] After the interference exposure is completed, the liquid crystal slurry no longer contains non-liquid crystal polymerizable monomers, but only contains liquid crystal polymerizable monomers, presenting a liquid crystal state and having liquid fluidity. Then, ordinary light sources are used to polymerize the liquid crystal polymerizable monomers to form liquid crystal polymers. The exposure wavelength is determined by the absorption wavelength range of the photoinitiator of the liquid crystal polymerizable monomers (generally, the same photoinitiator as the non-liquid crystal polymerizable monomers is used); or heating is used to polymerize the liquid crystal polymerizable monomers to form liquid crystal polymers, thus completing the preparation of all-solid-state H-PDLC.

[0071] The present application has no particular restrictions on the common light source used for light irradiation, as long as the liquid crystal polymerizable monomer can be polymerized to form a liquid crystal polymer, which can be selected according to the type of photoinitiator, for example, a common fluorescent lamp can be used for irradiation for 10 minutes to 60 minutes. The present application has no particular restrictions on the temperature and time of heating, as long as the liquid crystal polymerizable monomer can be polymerized to form a liquid crystal polymer, which can be selected according to the type of thermal polymerization initiator.

[0072] In some embodiments of the present application, in the liquid crystal slurry: the content of the liquid crystal polymerizable monomer is 4.5wt%-95wt%, the content of the non-liquid crystal polymerizable monomer is 0.5wt%-95wt%, and the content of the initiator is 0.05wt%-10wt%. In some embodiments of the present application, in the liquid crystal slurry: the mass percentage of the liquid crystal polymerizable monomer can be 4.5wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt%, 95wt% or a range consisting of any two values ​​therebetween; the mass percentage of the non-liquid crystal polymerizable monomer can be 0.5wt%, 1wt%, 3 .... %, 5wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt%, 95wt% or a range consisting of any two values ​​therebetween; the mass percentage of the initiator can be 0.05wt%, 0.1wt%, 0.5wt%, 1wt%, 3wt%, 5wt%, 10wt% or a range consisting of any two values ​​therebetween; the total amount of liquid crystalline polymerizable monomer, non-liquid crystalline polymerizable monomer and initiator is 100wt%.

[0073] In the present application, if a thermal polymerization initiator is used to initiate the polymerization of liquid crystal polymerizable monomers to form liquid crystal polymers, the initiator includes both a photoinitiator and a thermal polymerization initiator, and the specific amounts of the photoinitiator and the thermal polymerization initiator can be selected according to actual needs; if a photoinitiator is used to initiate the polymerization of liquid crystal polymerizable monomers to form liquid crystal polymers, the initiator only includes a photoinitiator.

[0074] In some embodiments of the present application, the method for preparing the accommodating space comprises the steps of:

[0075] providing a first substrate and a second substrate;

[0076] forming a first dissociable layer on a surface of the first substrate;

[0077] A sealant is formed between the first dissociable layer and the second substrate, and the sealant, the first dissociable layer and the second substrate define a receiving space.

[0078] In some embodiments of the present application, after forming the liquid crystal polymer and before obtaining the all-solid-state H-PDLC volume holographic grating, the method further includes: performing a dissociation treatment on the first dissociable layer to peel off the first dissociable layer and the first substrate.

[0079] The present application has no particular limitation on the materials of the first substrate and the second substrate, as long as the purpose of the invention of the present application can be achieved, for example, a glass substrate is used.

[0080] The present application does not particularly limit the size relationship between the first substrate and the second substrate, and the two can be the same or different. For the same second substrate, multiple first dissociable layers can be arranged opposite to each other, and multiple accommodating spaces can be formed with the frame sealant, thereby preparing multiple all-solid-state H-PDLC volume holographic gratings (the area of ​​the second substrate is larger than that of a single H-PDLC).

[0081] The present application has no particular limitation on the specific type of the frame sealant, as long as the purpose of the invention of the present application can be achieved, for example, 502, S-WB101R or SS85.

[0082] In some embodiments of the present application, the method for preparing the accommodating space comprises the steps of:

[0083] providing a first substrate and a second substrate;

[0084] forming a first dissociable layer on one surface of the first substrate; and forming a second dissociable layer on a side of the second substrate close to the first dissociable layer;

[0085] A frame sealant is formed between the first dissociable layer and the second dissociable layer, and the frame sealant, the first dissociable layer, and the second dissociable layer define the accommodation space.

[0086] In some embodiments of the present application, after forming the liquid crystal polymer and before obtaining the all-solid-state H-PDLC volume holographic grating, the following steps are further included:

[0087] performing a dissociation process on the first dissociable layer so that the first dissociable layer and the first substrate are peeled off;

[0088] The second dissociable layer is subjected to a dissociation treatment so that the second dissociable layer and the second substrate are peeled off.

[0089] The present application has no particular restrictions on the method for preparing the first dissociable layer and the second dissociated layer, as long as the purpose of the invention of the present application can be achieved, for example, coating is carried out by Spin (rotary coating) / Slit (slit coating) and Coater (coated paper coating), and after coating, a film is formed by exposure curing, UV curing or heat curing.

[0090] In some embodiments of the present application, the thickness of the first dissociable layer is 30 nm-500 μm.

[0091] In some embodiments of the present application, the thickness of the second dissociable layer is 30 nm-500 μm.

[0092] In some embodiments of the present application, the thickness of the first dissociable layer and the thickness of the second dissociable layer can be 30nm, 100nm, 300nm, 500nm, 800nm, 1μm, 5μm, 10μm, 50μm, 100μm, 300μm, 500μm or a range consisting of any two values ​​therebetween.

[0093] In some embodiments of the present application, the material forming the first dissociable layer is selected from a mechanical separation material (DBL), a laser viscosity reduction material or a UV viscosity reduction material.

[0094] In some embodiments of the present application, the material forming the second dissociable layer is selected from a mechanical separation material (DBL), a laser viscosity reduction material or a UV viscosity reduction material.

[0095] In some embodiments of the present application, the dissociation treatment is mechanical peeling, laser dissociation or UV light irradiation dissociation.

[0096] The following is a flowchart Figure 4 , the steps included in the preparation method of the all-solid-state H-PDLC volume holographic grating are further described.

[0097] (1)Reference Figure 4 As shown in a, a first substrate 11 is provided, and a first dissociable layer 12 with a thickness of 30nm-500μm is formed on one surface of the first substrate 11; a second substrate 21 is provided, and a second dissociable layer 22 with a thickness of 30nm-500μm is formed on one surface of the second substrate 21.

[0098] (2)Reference Figure 4 As shown in b, the first dissociable layer 12 and the second dissociable layer 22 are placed opposite to each other, and a sealant 31 is formed between the first dissociable layer 12 and the second dissociable layer 22 . The sealant 31 , the first dissociable layer 12 and the second dissociable layer 22 define a receiving space 41 .

[0099] (3)Reference Figure 4 As shown in c, the receiving space 41 is filled with liquid crystal slurry 51 .

[0100] (4)Reference Figure 4 As shown in FIG. d , interference exposure is performed to polymerize the non-liquid crystal polymerizable monomers to form a plurality of periodic structures composed of non-liquid crystal polymers 61 .

[0101] (5)Reference Figure 4 As shown in e, ordinary light irradiation or heating is used to polymerize the liquid crystal polymerizable monomers to form liquid crystal polymers 71 between adjacent periodic structures. The periodic structure composed of multiple non-liquid crystal polymers 61 and the liquid crystal polymers 71 between adjacent periodic structures form a grating.

[0102] (6)Reference Figure 4 As shown in FIG. 5 , the first dissociable layer 12 and the second dissociable layer 22 are subjected to a dissociation treatment, so that the first dissociable layer 12 and the first substrate 11, the second dissociable layer 22 and the second substrate 21 are peeled off from the grating, and the sealing glue 31 is removed to obtain a substrate-free all-solid-state H-PDLC volume holographic grating 1.

[0103] The following is a flowchart Figure 5 , the steps included in another method for preparing a fully solid-state H-PDLC volume holographic grating are further described.

[0104] (1)Reference Figure 5 As shown in a, a first substrate 11 is provided, and a first dissociable layer 12 with a thickness of 30 nm-500 μm is formed on one surface of the first substrate 11; and a second substrate 21 is provided.

[0105] (2)Reference Figure 5 As shown in b, the first dissociable layer 12 and the second substrate 21 are placed opposite to each other, and a sealing glue 31 is formed between the first dissociable layer 12 and the second substrate 21 . The sealing glue 31 , the first dissociable layer 12 and the second substrate 21 define a receiving space 41 .

[0106] (3)Reference Figure 5 As shown in c, the receiving space 41 is filled with liquid crystal slurry 51 .

[0107] (4)Reference Figure 5 As shown in FIG. d , interference exposure is performed to polymerize the non-liquid crystal polymerizable monomers to form a plurality of periodic structures composed of non-liquid crystal polymers 61 .

[0108] (5)Reference Figure 5As shown in e, ordinary light irradiation or heating is used to polymerize the liquid crystal polymerizable monomers to form liquid crystal polymers 71 between adjacent periodic structures. The periodic structure composed of multiple non-liquid crystal polymers 61 and the liquid crystal polymers 71 between adjacent periodic structures form a grating.

[0109] (6)Reference Figure 5 As shown in f, the first dissociable layer 12 is subjected to a dissociation treatment so that the first dissociable layer 12 and the first substrate 11 are peeled off from the grating, thereby obtaining a fully solid H-PDLC volume holographic grating 1 having a substrate (second substrate 21) on only one side.

[0110] In one embodiment of the present application, two polymerization systems with different initiation wavelengths are used to repeat the above Figure 4 or Figure 5 steps, each polymerization system constructs a grating periodic structure; or, a photoinitiated polymerization system is used to prepare non-liquid crystal polymers, and a thermal polymerization system (such as liquid crystal epoxy polymerizable monomers) is used to prepare liquid crystal polymers. At this time, since the liquid crystal epoxy polymerizable monomers are unlikely to polymerize during interference exposure, the process requirements for interference exposure are greatly reduced.

[0111] The present application mainly addresses the problem that the liquid fluidity of small molecule liquid crystals in general H-PDLC requires the use of upper and lower substrates for packaging when it is used. Liquid crystal polymers are used to replace the small molecule liquid crystals in ordinary H-PDLC to prepare all-solid-state H-PDLC, and then a substrate peeling process is used to prepare an all-solid-state, substrate-free H-PDLC, thereby effectively reducing the size of the device and avoiding the influence of the substrate on the optical properties of the device.

[0112] In one embodiment of the present application, Figure 6 As shown, a schematic diagram of a plurality of all-solid-state H-PDLC volume holographic grating structures prepared simultaneously is provided, wherein the area of ​​the second substrate 21 is larger than the area of ​​a single all-solid-state H-PDLC volume holographic grating 1; and two all-solid-state H-PDLC volume holographic gratings 1 and corresponding sealing glue 31 are provided on the same second substrate 21.

[0113] Glass can be the waveguide structure of the AR device. The diffracted light of the all-solid-state H-DPLC directly enters the waveguide and propagates in a specific direction according to the design. Multiple all-solid-state H-PDLCs can also be prepared on the same piece of glass at the same time. For example, when there are two all-solid-state H-PDLCs, they can be used as the input coupling holographic grating and output coupling holographic grating of the waveguide structure respectively.

[0114] The third aspect of the present application provides an optical device, comprising the all-solid-state H-PDLC volume holographic grating described in the first aspect of the present application or the all-solid-state H-PDLC volume holographic grating prepared by the method described in the second aspect of the present application.

[0115] Hereinafter, embodiments of the present application will be described in more detail with reference to examples.

[0116] Example 1

[0117] (1) 50 wt % of a liquid crystalline acrylate polymerizable monomer represented by formula (I), 48 wt % of pentaerythritol tetraacrylate (a non-liquid crystalline polymerizable monomer), 1.5 wt % of N-phenylglycine ethyl ester (a photoinitiator) and 0.5 wt % of Rose Bengal (CAS NO.: 632-69-9, a photoinitiator) were mixed uniformly to obtain a liquid crystal slurry.

[0118] (2) Figure 4 As shown in a, a mechanical separation material (DBL) is spin-coated on one surface of a first glass substrate 11 to form a first dissociable layer 12 with a thickness of 100 μm; and a mechanical separation material (DBL) is spin-coated on one surface of a second glass substrate 21 to form a second dissociable layer 22 with a thickness of 100 μm.

[0119] (3) Figure 4 As shown in b, the first dissociable layer 12 and the second dissociable layer 22 are placed opposite to each other, and a sealing glue 31 is formed between the first dissociable layer 12 and the second dissociable layer 22 using S-WB101R. The sealing glue 31, the first dissociable layer 12 and the second dissociable layer 22 define a receiving space 41.

[0120] (4) Figure 4 As shown in c, the liquid crystal slurry 51 prepared in step (1) is filled into the receiving space 41 by VAS.

[0121] (5) Figure 3 As shown in the figure, the interference exposure optical path is constructed, which mainly consists of a CW laser 101, a shutter 102, a beam expander 103, a beam splitter 104, a reflector 105, and a sample stage 106; Figure 4 As shown in (d), a 532nm laser wavelength is used for interference exposure, and the light power density is 7mW / cm 2 The illumination time is 10 minutes, so that the non-liquid crystal polymerizable monomers are polymerized to form a plurality of periodic structures composed of non-liquid crystal polymers 61, and the grating period direction is perpendicular to the direction of the angle bisector of the two interference light beams.

[0122] (6) Figure 4As shown in e, ordinary fluorescent lamps are used for irradiation, and the illumination time is 1 hour, so that the liquid crystal polymerizable monomers are polymerized to form liquid crystal polymers 71 between adjacent periodic structures. The periodic structure composed of multiple non-liquid crystal polymers 61 and the liquid crystal polymers 71 between adjacent periodic structures form a grating.

[0123] (7) Figure 4 As shown in FIG. 5 , the first dissociable layer 12 and the second dissociable layer 22 are dissociated by mechanical peeling, so that the first dissociable layer 12 and the first glass substrate 11, the second dissociable layer 22 and the second glass substrate 21 are peeled off from the grating, and the sealing glue 31 is removed to obtain a fully solid H-PDLC volume holographic grating 1 without a glass substrate.

[0124] Example 2

[0125] (1) 50 wt % of a liquid crystalline acrylate polymerizable monomer represented by formula (I), 48 wt % of pentaerythritol tetraacrylate (a non-liquid crystalline polymerizable monomer), 1.5 wt % of N-phenylglycine ethyl ester (a photoinitiator) and 0.5 wt % of Rose Bengal (CAS NO.: 632-69-9, a photoinitiator) were mixed uniformly to obtain a liquid crystal slurry.

[0126] (2) Figure 5 As shown in a, a mechanical separation material (DBL) is spin-coated on one surface of a first glass substrate 11 to form a first dissociable layer 12 with a thickness of 100 μm.

[0127] (3) Figure 5 As shown in b, the first dissociable layer 12 and the second glass substrate 21 are placed opposite to each other, and a sealing glue 31 is formed between the first dissociable layer 12 and the second glass substrate 21 using S-WB101R. The sealing glue 31, the first dissociable layer 12 and the second glass substrate 21 define a receiving space 41.

[0128] (4) Figure 5 As shown in c, the liquid crystal slurry 51 prepared in step (1) is filled into the receiving space 41 by VAS.

[0129] (5) Figure 3 As shown in the figure, the interference exposure optical path is constructed, which mainly consists of a CW laser 101, a shutter 102, a beam expander 103, a beam splitter 104, a reflector 105, and a sample stage 106; Figure 5 As shown in (d), the first interference exposure was performed using a laser wavelength of 532 nm, with a light power density of 7 mW / cm 2The illumination time is 10 minutes, so that the non-liquid crystal polymerizable monomers are polymerized to form a plurality of periodic structures composed of non-liquid crystal polymers 61, and the grating period direction is perpendicular to the direction of the angle bisector of the two interference light beams.

[0130] (6) Figure 5 As shown in e, ordinary light source fluorescent lamp is used for irradiation, and the illumination time is 1 hour, so that the liquid crystal polymerizable monomer is polymerized to form liquid crystal polymer 71 between adjacent periodic structures. The periodic structure composed of multiple non-liquid crystal polymers 61 and the liquid crystal polymers 71 between adjacent periodic structures form a grating.

[0131] (7) Figure 5 As shown in f, the first dissociable layer 12 is dissociated by mechanical peeling, so that the first dissociable layer 12 and the first glass substrate 11 are peeled off from the grating, and a fully solid H-PDLC volume holographic grating 1 having a glass substrate (second glass substrate 21) on only one side is obtained.

[0132] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. An all-solid-state H-PDLC volume holographic grating, comprising a plurality of periodic structures and liquid crystal polymers located between adjacent periodic structures, wherein the liquid crystal polymers are polymerized from liquid crystal polymerizable monomers, and the periodic structures are non-liquid crystal polymers, which are polymerized from non-liquid crystal polymerizable monomers.

2. The all-solid-state H-PDLC volume holographic grating according to claim 1, wherein: The refractive index modulation degree Δn between the liquid crystal polymer and the non-liquid crystal polymer is 0.001-0.

5.

3. The all-solid-state H-PDLC volume holographic grating according to claim 1 or 2, wherein: The liquid crystal polymer is obtained by polymerization using photopolymerization or thermal polymerization; the non-liquid crystal polymer is obtained by polymerization using photopolymerization.

4. A method for preparing a fully solid H-PDLC volume holographic grating, comprising the steps of: Prepare a liquid crystal slurry, wherein the liquid crystal slurry comprises a liquid crystal polymerizable monomer, a non-liquid crystal polymerizable monomer and an initiator; Filling the containing space with the liquid crystal slurry, and then performing interference exposure, so that the non-liquid crystal polymerizable monomer is polymerized to form a plurality of periodic structures composed of non-liquid crystal polymers; The liquid crystal slurry containing the non-liquid crystal polymer is irradiated with light or heated to polymerize the liquid crystal polymerizable monomer to form liquid crystal polymers between adjacent periodic structures, thereby obtaining the all-solid-state H-PDLC volume holographic grating.

5. The preparation method according to claim 4, wherein: In the liquid crystal slurry: the content of the liquid crystal polymerizable monomer is 4.5wt%-95wt%, the content of the non-liquid crystal polymerizable monomer is 0.5wt%-95wt%, and the content of the initiator is 0.05wt%-10wt%.

6. The preparation method according to claim 4, wherein The method for preparing the accommodation space comprises the steps of: providing a first substrate and a second substrate; forming a first dissociable layer on a surface of the first substrate; forming a sealing glue between the first dissociable layer and the second substrate, wherein the sealing glue, the first dissociable layer and the second substrate define the accommodation space; Preferably, after forming the liquid crystal polymer and before obtaining the all-solid H-PDLC volume holographic grating, the method further comprises the following steps: The first dissociable layer is subjected to a dissociation treatment so as to peel off the first dissociable layer and the first substrate.

7. The preparation method according to claim 4, wherein The method for preparing the accommodation space comprises the steps of: providing a first substrate and a second substrate; forming a first dissociable layer on one surface of the first substrate; and forming a second dissociable layer on a side of the second substrate close to the first dissociable layer; forming a sealant between the first dissociable layer and the second dissociable layer, wherein the sealant, the first dissociable layer and the second dissociable layer define the accommodation space; Preferably, after forming the liquid crystal polymer and before obtaining the all-solid H-PDLC volume holographic grating, the method further comprises the following steps: performing a dissociation process on the first dissociable layer so that the first dissociable layer and the first substrate are peeled off; The second dissociable layer is subjected to a dissociation treatment so that the second dissociable layer and the second substrate are peeled off.

8. The preparation method according to claim 6 or 7, wherein: The thickness of the first dissociable layer is 30 nm-500 μm; The material forming the first dissociable layer is selected from a mechanical separation material, a laser viscosity reduction material or a UV viscosity reduction material; Preferably, the dissociation treatment is mechanical peeling, laser dissociation or UV light irradiation dissociation.

9. The preparation method according to claim 7, wherein: The thickness of the second dissociable layer is 30nm-500μm; The material forming the second releasable layer is selected from a mechanical separation material, a laser viscosity reduction material or a UV viscosity reduction material.

10. An optical device comprising the all-solid-state H-PDLC volume holographic grating according to any one of claims 1 to 3 or the all-solid-state H-PDLC volume holographic grating prepared by the method according to any one of claims 4 to 9.

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