Reversible chiral regulation type circular polarization laser device and preparation method and application thereof

Abstract

The invention provides a reversible chiral regulation type circular polarization laser device and a preparation method and application thereof. The reversible chiral regulation type circular polarization laser device structurally comprises a lower substrate, a light modulation layer, an upper substrate, an isolation layer and a gain medium layer from bottom to top in sequence. According to the reversible chiral regulation and control type circular polarization laser device, cholesteric liquid crystal doped with a light-controlled molecular motor is used as a light modulation layer, an organic-inorganic mixed perovskite polycrystalline film is used as a light gain medium, amplified spontaneous emission gain is generated through laser pumping of the perovskite polycrystalline film, and through light modulation of CLC, the light gain of the light modulation layer is improved. Therefore, high-performance circular polarization laser is emitted. Under the irradiation of ultraviolet light, cis-trans isomerization occurs to the light-controlled molecular motor, so that CLC chirality is reversed, and the circular polarization asymmetry factor of emergent laser is up to-1.38-1.22. By adjusting the ultraviolet light power and replacing the perovskite polycrystalline thin film with different halogen components, the laser device can realize multi-color, different-chirality and high-circular-polarization-degree laser emission.

Description

Technical Field

[0001] The present invention relates to the technical field of circularly polarized lasers, and in particular to a reversible chirality-regulating circularly polarized laser device, a preparation method thereof, and applications thereof. Background Art

[0002] Circularly polarized laser refers to a coherent light source in which the end of the electric field vector of the light wave rotates spirally in the direction of propagation. Its polarization state can be divided into left-handed circular polarization and right-handed circular polarization according to the direction of rotation. Compared with ordinary linearly polarized laser, circularly polarized laser carries additional spin angular momentum and polarization state information, which makes it play an important role in specific fields. For example, circularly polarized laser with orthogonal characteristics can be used as a 3D display light source to build 3D laser displays with ultra-high contrast and comfort; the selective chirality recognition of circularly polarized laser with chiral biomolecules and biological processes plays an important role in the detection of drug activity and intracellular localization. Combined with spin angular momentum multiplexing technology, circularly polarized laser can increase the channel capacity of optical communication systems to hundreds of times that of traditional technologies.

[0003] Circular polarization asymmetry factor (g lum ) is a key indicator for quantifying the purity of circularly polarized light, and its calculation formula is g lum =2*(I L -I R ) / (I L +I R ), where I L and I R represent the intensities of the left-hand circular polarization component and the right-hand circular polarization component, g lum The theoretical range is -2 to +2. Currently, commercial circularly polarized lasers are obtained by adding optical elements to the laser emission path, which means that the laser itself cannot directly emit circularly polarized lasers. Combining cholesteric liquid crystal (CLC) with optical rotation effect to prepare circularly polarized lasers is an efficient way to obtain high-performance circularly polarized laser emission. As a one-dimensional photonic crystal, CLC has many small molecule liquid crystal monomers arranged periodically to form an ordered repeating structure. Therefore, it has Bragg reflection characteristics similar to crystals and can selectively reflect light of specific wavelengths. In addition, due to the spiral torque of the chiral dopant, the director between each layer of the small molecule liquid crystal inside the CLC will rotate at a certain angle, so that its periodic structure is arranged in a spiral twisted shape. Because of this, CLC will have a screening effect on circularly polarized light of a specific wavelength, which is also called the photon bandgap characteristic. When the incident wavelength matches the photon bandgap region of the CLC, the part of the circularly polarized light with the same chirality as the CLC will be reflected, and the other part of the circularly polarized light will be transmitted. The circularly polarized laser devices prepared based on this principle all have high g lum , and good device stability.

[0004] In addition to being able to produce high-purity circularly polarized laser light, the functional integration of lasers has become the next research hotspot. The conventional method of using CLC as a light modulation layer to achieve circularly polarized laser light has the disadvantage that the chirality of CLC is usually determined by the chiral dopant added during the preparation process. Therefore, the chirality of CLC cannot usually be switched arbitrarily after preparation. Therefore, in this case, researchers generally need to produce a large number of CLC materials with different photonic band gaps and different chiralities to match lasers of different wavelengths in order to achieve multi-color, different chiral circularly polarized laser emission to meet the needs of practical applications.

[0005] In summary, it is of great significance to develop a laser device with the ability to tune circularly polarized light to emit circularly polarized lasers of different chirality on demand. Summary of the Invention

[0006] In response to the defects and shortcomings in the prior art, the present invention provides a reversible chirality-controlled circularly polarized laser device, its preparation method, and application. The reversible chirality-controlled circularly polarized laser device uses a cholesteric liquid crystal (CLC) doped with a light-controlled molecular motor as a light modulation layer and an organic-inorganic hybrid perovskite polycrystalline film as a light gain medium. The perovskite polycrystalline film is pumped by laser to generate amplified spontaneous emission (ASE) gain, which is modulated by the CLC light to emit high-performance circularly polarized laser. Under ultraviolet light irradiation, the light-controlled molecular motor undergoes cis-trans isomerization, resulting in a reversal of the CLC chirality, thereby achieving a circular polarization asymmetry factor (g) of the emitted laser. lum ) as high as -1.38 to 1.22 (theoretical range is -2 to 2). By adjusting the UV light power and replacing perovskite polycrystalline films with different halogen compositions, the laser device can achieve multi-color, high-chirality, high-circular-polarization laser output. This invention offers advantages such as good repeatability and high functional integration, providing new insights into the field of circularly polarized lasers.

[0007] One object of the present invention is to provide a reversible chirality-controlled circularly polarized laser device, wherein the structure of the reversible chirality-controlled circularly polarized laser device comprises, from bottom to top, a lower substrate, an optical modulation layer, an upper substrate, an isolation layer, and a gain medium layer;

[0008] The light modulation layer is a liquid crystal mixture, and the liquid crystal mixture is a cholesteric liquid crystal doped with a chiral dopant;

[0009] The gain medium layer is an organic-inorganic hybrid perovskite polycrystalline thin film;

[0010] The light modulation layer is arranged between the lower substrate and the upper substrate to form a liquid crystal box structure;

[0011] A parallel alignment layer is provided between the lower substrate and the light modulation layer, and between the upper substrate and the light modulation layer.

[0012] Furthermore, the liquid crystal mixture includes a chiral dopant and a small molecule nematic liquid crystal.

[0013] Furthermore, the chiral dopant is a light-controlled molecular motor; and the small molecule nematic liquid crystal is a mixed liquid crystal E7.

[0014] Furthermore, the mass ratio of the chiral dopant to the small molecule nematic liquid crystal is (3-6):(94-97).

[0015] Furthermore, the isolation layer is a PET film with an ultraviolet absorber added.

[0016] Furthermore, the organic-inorganic hybrid perovskite polycrystalline film is a lead halide methylamine MAPbX3 perovskite polycrystalline film;

[0017] Wherein, X is Cl, Cl m Br 3-m Br, Br m I 3-m , any one of I, 0≤m≤3.

[0018] Furthermore, the lead halide methylamine MAPbX3 perovskite polycrystalline film is prepared by a one-step spin coating method.

[0019] Another object of the present invention is to provide a method for preparing the above-mentioned reversible chirality-controllable circularly polarized laser device, comprising the following steps:

[0020] S1. Mixing a chiral dopant and a small molecule nematic liquid crystal, adding a solvent, and heating and stirring under light conditions until the solvent evaporates and the mixture becomes a milky white thick paste, thereby obtaining a liquid crystal mixture;

[0021] S2. Spin-coating a PVA solution on the surfaces of the two substrates, heating, annealing, and drying, and then performing rubbing alignment to form a parallel alignment layer, thereby obtaining an upper substrate and a lower substrate with a parallel alignment layer; mixing a spacer and a UV curable adhesive to prepare a liquid crystal cell thickness control material, and adding the material between the upper substrate and the lower substrate with the parallel alignment layer, pressing the upper and lower substrates to fully disperse the spacer, assembling the liquid crystal cell, and curing the liquid crystal cell to obtain a parallel alignment liquid crystal cell;

[0022] S3, filling the liquid crystal mixture into the parallel-aligned liquid crystal cell under heating conditions to obtain a light modulation layer;

[0023] S4. First, a perovskite precursor solution is prepared, and a substrate and a PET film serving as an isolation layer are assembled into a spin-coated substrate. The perovskite precursor solution is then spin-coated on the isolation layer, and an organic-inorganic hybrid perovskite polycrystalline thin film is formed after annealing. A PMMA protective layer is then spin-coated, and a gain medium layer is obtained after a second annealing.

[0024] S5. Use optical double-sided tape to bond the lower surface of the isolation layer and the surface of the upper substrate together to obtain a reversible chirality-controlled circularly polarized laser device.

[0025] Furthermore, in step S1, the heating temperature is 70-90°C.

[0026] Furthermore, in step S3, the heating temperature is 70-90°C.

[0027] Another object of the present invention is to provide applications of the above-mentioned reversible chirality-controllable circularly polarized laser device in optical communications, 3D displays, and optical information storage.

[0028] The present invention has the following beneficial effects:

[0029] (1) The reversible chirality-regulated circularly polarized laser device disclosed in the present invention utilizes a CLC doped with a light-controlled molecular motor as a light modulation layer and an organic-inorganic hybrid perovskite polycrystalline film as a gain medium layer. The amplified spontaneous emission (ASE) of the perovskite polycrystalline film layer excited by the pump source first passes through the CLC layer and then radiates outward. Under ultraviolet light irradiation, the light-controlled molecular motor undergoes cis-trans isomerization, thereby causing the CLC to undergo chirality reversal, achieving the emission of circularly polarized ASE of different chirality, and the circular polarization asymmetry factor (g lum ) is as high as -1.38~1.22 (theoretical range is -2~2).

[0030] (2) The reversible chirality-regulated circularly polarized laser device disclosed in the present invention is combined with perovskite polycrystalline films of different halogen components, and through the precise control of ultraviolet light power, it is possible to arbitrarily achieve the combination of circularly polarized lasers of different wavelengths and different chiralities, meeting the requirements of highly integrated device functions.

[0031] (3) The reversible chirality-regulated circularly polarized laser device disclosed in the present invention adopts a simple preparation method, does not require complex processes, has a simple structure, good repeatability and good stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The schematic diagram of the structure of the reversible chirality-controllable circularly polarized laser device in Example 1 is shown, wherein layer 100 is the lower glass substrate, layer 101 is the upper glass substrate, layer 200 is the light modulation layer, layer 300 is the optical double-sided tape, layer 400 is the isolation layer, and layer 500 is the optical gain medium layer;

[0033] Figure 2 Schematic diagram showing the optical path used in the test example; Description of the Figures: 11 - laser excitation source; 12 - reflector; 13 - laser device; 14 - semi-transparent and semi-reflective mirror; 15 - ultraviolet light source; 16 - polarization beam splitter; 17 - linear polarizer; 18 - lens; 19 - spectrometer;

[0034] Figure 3 shows the spectrum of the perovskite polycrystalline thin film prepared in Example 1;

[0035] Figure 4 The cis-trans isomerization chemical process of the light-controlled molecular motor used in Example 1 is shown;

[0036] Figure 5 The graph shows the change of the reflection band of the cholesteric liquid crystal prepared in Example 1 under ultraviolet light irradiation;

[0037] in,

[0038] Figure 5 (a) shows that when ultraviolet light irradiates cholesteric liquid crystal, its reflection band gradually red-shifts from the initial ultraviolet region to the near-infrared region and finally leaves the detection range;

[0039] Figure 5 (b) shows that when UV light is continuously irradiated, the cholesteric liquid crystal undergoes chirality inversion, and its reflection band reappears in the detection window. It continuously shifts to the blue side under UV stimulation, and finally stabilizes in the green light band.

[0040] Figure 6 The graph showing the change of the asymmetry factor of the laser device prepared in Example 1 over time is shown;

[0041] Figure 7 shows the fluorescence spectrum of the perovskite polycrystalline thin film prepared in Comparative Example 1;

[0042] Figure 8 The graph showing the change in reflection band of the cholesteric liquid crystal prepared in Comparative Example 2 under ultraviolet light irradiation is shown. DETAILED DESCRIPTION

[0043] In order to more clearly illustrate the technical solutions of the present invention, the following examples are given. Unless otherwise stated, the raw materials, reactions and post-processing methods mentioned in the examples are common raw materials on the market and technical methods well known to those skilled in the art.

[0044] The terms "preferred," "preferably," "more preferred," and the like, used herein, refer to embodiments of the invention that may provide certain benefits under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the invention.

[0045] It should be understood that, except in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and appended claims are approximations that may vary depending upon the desired properties to be obtained by the present invention.

[0046] The following materials are used in this invention:

[0047] Small molecule nematic liquid crystal E7: brand XY250226001, purchased from Nanjing Xinyao Technology Co., Ltd.

[0048] Light-controlled molecular motor: 9-(2-Phenyl-2,3-dihydro-cyclopenta[a]naphthalen-1-ylidene)-9H-fluorene 1 .

[0049] PVA: brand P815727, purchased from Maclean.

[0050] 7 μm glass ball spacer: brand H07E05-5, purchased from Suzhou Nanovita Technology Co., Ltd.; 30 μm glass ball spacer: brand F08E04-R, purchased from Suzhou Nanovita Technology Co., Ltd.

[0051] UV curing adhesive: brand LB-3706C, purchased from Shenzhen Libang New Material Technology Co., Ltd.

[0052] PET film: purchased from Shenzhen Fanak Optoelectronics Technology Co., Ltd., and a UV absorber was added to the film.

[0053] PET film without UV absorber: brand L112560, purchased from Shanghai Dibai Biotechnology Co., Ltd.

[0054] PMMA: brand P821343, purchased from Maclean.

[0055] The water in the embodiments of the present invention is deionized water.

[0056] The “parts” in the embodiments of the present invention refer to parts by mass.

[0057] Example 1

[0058] A reversible chirality-regulatable circularly polarized laser device, wherein the structure of the reversible chirality-regulatable circularly polarized laser device is, from bottom to top, as follows: lower substrate (2 mm) / optical modulation layer (7 μm) / upper substrate (2 mm) / optical double-sided tape (50 μm) / isolation layer (100 μm) / gain medium layer (200 nm);

[0059] The preparation method is as follows:

[0060] S1. Take 0.2 g of the raw materials, small molecule nematic liquid crystal E7 and light-controlled molecular motor (small molecule nematic liquid crystal E7: light-controlled molecular motor = 95.3:4.7, m / m). Place the raw materials in a 3 mL brown sample bottle under yellow light. Add a clean stirring magnet to the sample bottle. Then, use a pipette to add 1 mL of dichloromethane as a solvent to the sample bottle. Place the sample bottle on an 80°C heating stirring table to evaporate for 3 hours, until the mixture becomes a milky white, thick paste, to obtain a liquid crystal mixture.

[0061] S2. Take two clean, ordinary glass sheets with a side length of 2 cm. Treat the glass surfaces with an ozone generator for 10 minutes. Then, place them on a spin coater and spin-coat a 5 wt% aqueous solution of PVA at 2000 rpm. After spin coating, anneal the glass on a 70°C hot plate for 30 minutes. After annealing, rub the PVA-coated side of the glass substrate on a velvet cloth for parallel alignment. Mark the rubbing direction to obtain upper and lower substrates with parallel alignment layers.

[0062] Take a small amount of 7μm glass ball spacers and UV curing adhesive and mix them at a mass fraction ratio of 1:99 to obtain the liquid crystal cell thickness control material;

[0063] Apply a small amount of the liquid crystal cell thickness control material to the four corners of the lower substrate, take the upper substrate, align the upper and lower substrates according to the rubbing direction of the parallel alignment layer, so that the rubbing directions of the parallel alignment layers of the upper and lower substrates are parallel to each other, and then put the upper and lower substrates together and press lightly to allow the UV curing adhesive with spacers to fully spread between the upper and lower substrates to obtain a pre-treated liquid crystal cell. The pre-treated liquid crystal cell is subjected to UV curing treatment to obtain a parallel alignment liquid crystal cell;

[0064] S3. Under yellow light conditions, place the parallel-oriented liquid crystal box on a 70°C hot plate and preheat for 10 minutes. Quickly transfer the liquid crystal mixture from the 80°C heated stirring plate to a 70°C hot plate, use a pipette to draw 10 μL of the liquid crystal mixture, and slowly inject it along one edge of the liquid crystal box. Under capillary action, the liquid crystal mixture will flow from the edge of the filled side to the opposite edge, and finally fill the entire liquid crystal box space. In addition, under the anchoring force of the parallel-oriented layer, the liquid crystal mixture will self-assemble into a spiral structure to obtain a light modulation layer;

[0065] S4. PbI2 and MAI (PbI2:MAI=1:1, n / n) were dissolved in a DMF-DMSO mixed solvent (DMF:DMSO=9:1, v / v), and stirred at 60°C for 24 h to fully dissolve the precursor ions in the mixed solvent to obtain a perovskite precursor solution;

[0066] Take clean ordinary glass, cut a PET film of appropriate size as an isolation layer, and glue the two together with optical double-sided tape to obtain a spin coating substrate;

[0067] The preparation of perovskite polycrystalline thin film was carried out in a glove box. 40 μL of DMF was dropped on the isolation layer of the spin-coated substrate and spun at 2000 rpm for 20 seconds to allow the substrate to be pre-infiltrated. Then 40 μL of the perovskite precursor solution was spun at 2800 rpm for 45 seconds, and chlorobenzene was added as an anti-solvent at the 20th second. The substrate was then moved to a hot stage and annealed at 100°C for 20 minutes to obtain an organic-inorganic hybrid perovskite polycrystalline thin film. In order to maintain the integrity of the film, 80 μL of a 50 mg / mL PMMA solution dissolved in toluene was spin-coated on the annealed film and placed on a 100°C hot stage for secondary annealing for 20 minutes to obtain a gain medium layer;

[0068] S5. Peel off the gain medium layer together with the isolation layer, and stick the lower surface of the isolation layer to the outer surface of the upper substrate of the liquid crystal box by optical double-sided tape to obtain a reversible chirality controllable circularly polarized laser device.

[0069] Figure 1 A schematic diagram of the structure of the reversible chirality-controlled circularly polarized laser device in Example 1 is shown, wherein layer 100 is the lower glass substrate, layer 101 is the upper glass substrate, layer 200 is the light modulation layer, layer 300 is the optical double-sided tape, layer 400 is the isolation layer, and layer 500 is the optical gain medium layer.

[0070] Example 2

[0071] A reversible chirality-controlled circularly polarized laser device. The preparation steps of Example 2 and Example 1 are basically the same, except that the perovskite precursor raw material is changed to prepare perovskite polycrystalline films with different halogen components, thereby realizing a multi-color luminescent gain medium layer, thereby realizing circularly polarized laser emission of different colors.

[0072] The specific differences are:

[0073] The perovskite precursor raw materials used in step S4 are different. In this embodiment, PbBr2 and MABr with a molar ratio of 1:1 are used as precursors in step S4.

[0074] Example 3

[0075] A reversible chirality-controlled circularly polarized laser device. The preparation steps of Example 3 are basically the same as those of Example 1, except that the perovskite precursor raw material is changed to prepare perovskite polycrystalline films with different halogen components, thereby realizing a multi-color luminescent gain medium layer, thereby realizing circularly polarized laser emission of different colors.

[0076] The specific differences are:

[0077] The perovskite precursor raw materials used in step S4 are different. In this embodiment, PbCl2 and MACl with a molar ratio of 1:1 are used as precursors in step S4.

[0078] The reversible chirality controllable circularly polarized laser devices prepared in Examples 1-3 above all require femtosecond pulse laser for pumping excitation. When the gain medium layer is pumped, narrow linewidth, high energy amplified spontaneous emission (ASE) will radiate outward from the surface of the gain medium layer. At this time, with the help of the optical modulation layer, the non-polarized ASE will be converted into a high asymmetry factor (g lum More importantly, the optical modulation layer can achieve chirality reversal by adjusting the ultraviolet light power.

[0079] The reversible chirality-controlled circularly polarized laser devices produced in Examples 1-3 above also require a UV light source with precisely controlled irradiation power. Under varying UV light intensities, the degree of reversible cis-trans isomerization of the light-controlled molecular motor varies, and thus the degree to which it affects the pitch change of the cholesteric liquid crystal (CLC) is also different. Based on this characteristic, by precisely controlling the UV light power, the CLC photonic bandgap can be positioned at any point during the reversal process. Based on this, combined with a gain medium layer whose emission wavelength falls within the photonic bandgap, the reversible chirality-controlled circularly polarized laser device can achieve multi-color, customizable circularly polarized laser output with varying chirality.

[0080] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

[0081] Comparative Example 1

[0082] A laser device, the device structure, preparation method, raw materials used and component ratio of the laser device are the same as those in Example 1, the only difference is that the isolation layer described in Comparative Example 1 uses a PET film that does not contain a UV absorber.

[0083] Comparative Example 2

[0084] A laser device, the device structure, preparation method, and raw materials used in the laser device are the same as those in Example 1, with the only difference being that, in the process of preparing the liquid crystal box in Comparative Example 2, 30 μm glass beads are used as spacers to prepare a liquid crystal box with a box thickness of 30 μm.

[0085] Test Case

[0086] Test items: fluorescence spectrum of the gain medium layer (perovskite polycrystalline thin film), reflection spectrum of the light modulation layer (cholesteric liquid crystal), and circular polarization performance of the laser device.

[0087] The fluorescence spectrum test method of the perovskite polycrystalline film is as follows: the perovskite polycrystalline film prepared in step S4 of Example 1 is placed in an optical path sample holder, pumped and excited by a femtosecond pulse laser with a wavelength of 515 nm and a frequency of 10 kHz, and the signal is collected by a spectrometer.

[0088] The reflection spectrum test method of the cholesteric liquid crystal is as follows: take the CLC prepared in step S3 of Example 1, use the reflection mode of a spectrometer, and directly measure the reflection spectrum of the CLC under ultraviolet light irradiation.

[0089] The circular polarization performance test method of the laser device is: Figure 2 The optical path diagram shown is for testing.

[0090] Figure 2 A schematic diagram of the optical path used in the test example is shown; Description of the accompanying drawings: 11 - laser excitation source; 12 - reflector; 13 - laser device; 14 - semi-transparent and semi-reflective mirror; 15 - ultraviolet light source; 16 - polarization beam splitter; 17 - linear polarizer; 18 - lens; 19 - spectrometer.

[0091] The laser device in Example 1 is pumped on one side of the gain medium layer using a femtosecond pulse laser with a wavelength of 515nm and a frequency of 10KHz, and at the same time, the light modulation layer is irradiated on one side using 365nm ultraviolet light. The perovskite polycrystalline film generates amplified spontaneous emission (ASE) under the pumping action of the pump light, and then emits circularly polarized laser light on one side of the light modulation layer after being tuned by the cholesteric liquid crystal (CLC). The circularly polarized laser light is converted into vertical and horizontal linear polarization components after passing through the polarization beam splitter, and then passes through the linear polarizer and is received by two spectrometers respectively under the convergence action of the lens to obtain a left-handed circular polarization component and a right-handed circular polarization component. According to the circular polarization asymmetry factor formula g lum =2*(I L -I R ) / (I L +I R ), the circularly polarized light characteristics of the laser emitted by the laser device at each moment can be calculated.

[0092] Figure 3 shows the spectrum of the perovskite polycrystalline thin film prepared in Example 1;

[0093] Figure 4 The cis-trans isomerization chemical process of the light-controlled molecular motor used in Example 1 is shown;

[0094] Figure 5 The graph shows the change of the reflection band of the cholesteric liquid crystal prepared in Example 1 under ultraviolet light irradiation;

[0095] in,

[0096] Figure 5 (a) shows that when ultraviolet light irradiates cholesteric liquid crystal, its reflection band gradually red-shifts from the initial ultraviolet region to the near-infrared region and finally leaves the detection range;

[0097] Figure 5 (b) shows that when UV light is continuously irradiated, the cholesteric liquid crystal undergoes chirality inversion, and its reflection band reappears in the detection window. It continuously shifts to the blue side under UV stimulation, and finally stabilizes in the green light band.

[0098] Figure 6 The graph showing the change of the asymmetry factor of the laser device prepared in Example 1 over time is shown;

[0099] Figure 7 shows the fluorescence spectrum of the perovskite polycrystalline thin film prepared in Comparative Example 1;

[0100] Figure 8 The graph showing the change in reflection band of the cholesteric liquid crystal prepared in Comparative Example 2 under ultraviolet light irradiation is shown.

[0101] Depend on Figure 3It can be seen that a characteristic ASE peak with narrow line width and high intensity appears at 790nm.

[0102] Depend on Figure 4 It can be seen that under ultraviolet light irradiation, the light-controlled molecular motor will undergo a reversible cis-trans isomerization reaction, transforming from the stable p configuration to the unstable m configuration; at the same time, the reversible reaction can be carried out in the opposite direction through temperature treatment, which is the basis of the light-controlled circular polarization properties.

[0103] Depend on Figure 5 It can be seen that under ultraviolet light irradiation, the light-controlled molecular motor undergoes cis-trans isomerization, causing its own structure to distort. At this time, the helical torque provided by the molecular motor to the small molecule nematic phase will decrease, and the CLC will not be able to maintain its original helical periodic structure, resulting in structural changes and an increase in the pitch. According to the Bragg reflection law, the CLC reflection wavelength begins to increase, so the reflection band spectrum shows a red-shift trend. When the molecular motor helical torque drops to 0, the molecular motor no longer provides helical torque, and the small molecule nematic phase returns to an isotropic state. With continued ultraviolet light irradiation, the degree of molecular motor isomerization continues to increase. At this time, the small molecule nematic phase liquid crystal will be subjected to a force opposite to the original twisting direction, and the CLC undergoes chirality reversal. As the degree of isomerization deepens, the torque provided by the molecular motor to the small molecule nematic phase becomes increasingly stronger, so the CLC pitch decreases, the wavelength of the CLC reflection band decreases, and the reflection band spectrum shows a blue-shift trend.

[0104] Depend on Figure 6 It can be seen that under ultraviolet light irradiation, the CLC photon bandgap (reflection band) begins to redshift. When the reflection band does not match the perovskite lasing peak, the device emits unpolarized light. When the reflection band moves to cover the lasing peak, the perovskite's ASE is modulated by the CLC and becomes a right-handed circularly polarized laser with an asymmetry factor of -1.18. The CLC then undergoes a chirality inversion, and the reflection band subsequently blueshifts. When the reflection band meets the perovskite's ASE peak again, the device emits right-handed circularly polarized laser with an asymmetry factor of 1.09.

[0105] Depend on Figure 7 It can be seen that since the isolation layer uses a PET film without a UV absorber, under UV irradiation, the amplified spontaneous emission (ASE) process inside the gain medium layer competes with physical processes such as stimulated absorption and stimulated emission, resulting in a decrease in ASE intensity and an increase in photoluminescence intensity, making the gain medium layer unusable.

[0106] Depend on Figure 8It can be seen that because 30μm glass beads were used as spacers during the preparation of the liquid crystal cell, a cell thickness of 30μm was produced. This excessive thickness prevented UV light from fully penetrating the CLC. The isomerization degree of the light-controlled molecular motors within the CLC exhibited a gradient distribution along the direction of UV irradiation, thus affecting the helicity of the small-molecule liquid crystals and, in turn, weakening the shift in the CLC's reflection band, rendering the light-controlling layer unusable.

[0107] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

[0108] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A reversible chirality-controllable circularly polarized laser device, characterized in that: The structure of the reversible chirality controllable circular polarization laser device includes, from bottom to top, a lower substrate, a light modulation layer, an upper substrate, an isolation layer, and a gain medium layer; The light modulation layer is a liquid crystal mixture, and the liquid crystal mixture is a cholesteric liquid crystal doped with a chiral dopant; The gain medium layer is an organic-inorganic hybrid perovskite polycrystalline thin film; The light modulation layer is arranged between the lower substrate and the upper substrate to form a liquid crystal box structure; A parallel alignment layer is provided between the lower substrate and the light modulation layer, and between the upper substrate and the light modulation layer.

2. The reversible chirality-controllable circularly polarized laser device according to claim 1, characterized in that: The liquid crystal mixture includes a chiral dopant and a small molecule nematic liquid crystal.

3. The reversible chirality-controllable circularly polarized laser device according to claim 2, characterized in that: The chiral dopant is a light-controlled molecular motor; the small molecule nematic liquid crystal is a mixed liquid crystal E7.

4. The reversible chirality-controllable circularly polarized laser device according to claim 2, characterized in that: The mass ratio of the chiral dopant to the small molecule nematic liquid crystal is (3-6):(94-97).

5. The reversible chirality-controllable circularly polarized laser device according to claim 1, characterized in that: The isolation layer is a PET film added with an ultraviolet absorber.

6. The reversible chirality-controllable circularly polarized laser device according to claim 1, characterized in that: The organic-inorganic hybrid perovskite polycrystalline film is a lead halide methylamine MAPbX3 perovskite polycrystalline film; Wherein, X is Cl, Cl m Br 3-m Br, Br m I 3-m , any one of I, 0≤m≤3.

7. The reversible chirality-controllable circularly polarized laser device according to claim 6, characterized in that: The lead halide methylamine MAPbX3 perovskite polycrystalline film is prepared by a one-step spin coating method.

8. The method for preparing the reversibly chirality-controllable circularly polarized laser device according to any one of claims 1 to 7, characterized in that: The steps include: S1. Mixing a chiral dopant and a small molecule nematic liquid crystal, adding a solvent, and heating and stirring under light conditions until the solvent evaporates and the mixture becomes a milky white thick paste, thereby obtaining a liquid crystal mixture; S2. Spin-coating a PVA solution on the surfaces of the two substrates, heating, annealing, and drying, and then performing rubbing alignment to form a parallel alignment layer, thereby obtaining an upper substrate and a lower substrate with a parallel alignment layer; mixing a spacer and a UV curable adhesive to prepare a liquid crystal cell thickness control material, and adding the material between the upper substrate and the lower substrate with the parallel alignment layer, pressing the upper and lower substrates to fully disperse the spacer, assembling the liquid crystal cell, and curing the liquid crystal cell to obtain a parallel alignment liquid crystal cell; S3, filling the liquid crystal mixture into the parallel-aligned liquid crystal cell under heating conditions to obtain a light modulation layer; S4. First, a perovskite precursor solution is prepared, and a substrate and a PET film serving as an isolation layer are assembled into a spin-coated substrate. The perovskite precursor solution is then spin-coated on the isolation layer, and an organic-inorganic hybrid perovskite polycrystalline thin film is formed after annealing. A PMMA protective layer is then spin-coated, and a gain medium layer is obtained after a second annealing. S5. Use optical double-sided tape to bond the lower surface of the isolation layer and the surface of the upper substrate together to obtain a reversible chirality-controlled circularly polarized laser device.

9. The method for preparing a reversible chirality-controllable circularly polarized laser device according to claim 8, characterized in that: In step S1, the heating temperature is 70-90°C.

10. Application of the reversible chirality-controllable circularly polarized laser device according to any one of claims 1 to 7 in optical communications, 3D displays, and optical information storage.

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