Intensity-adjustable interface scattering type liquid crystal optical switch and working method thereof

Abstract

The invention discloses an intensity-adjustable interface scattering type liquid crystal optical switch and a working method thereof. The intensity-adjustable interface scattering type liquid crystal optical switch comprises a liquid crystal layer (1), polymer layers (2) are arranged on the upper face and the lower face of the liquid crystal layer (1) respectively, transparent electrode layers (3) are arranged on the outer side faces of the polymer layers (2), and transparent substrates (4) are arranged on the outer side faces of the transparent electrode layers (3); the polymer layer (2) is used as a rough interface of the liquid crystal layer (1); the light transmittance is adjusted by controlling the refractive index difference between the polymer layer and the liquid crystal layer, switching of the switch is achieved, and the liquid crystal display has the advantages of being low in driving voltage and high in light transmittance.

Description

Technical Field

[0001] The invention relates to the technical field of optical switches, and in particular to an intensity-adjustable interface scattering liquid crystal optical switch and a working method thereof. Background Art

[0002] Optical switches are important dimming devices, mainly used for switching optical transmission paths, adjusting beam intensity, phase control, and polarization filtering. They have been widely used in optical fiber communications, liquid crystal displays, optical imaging, and other fields. Liquid crystal optical switches are electrically controlled dimming devices that utilize the photoelectric properties of liquid crystal materials. Compared with traditional mechanical optical switches, liquid crystal optical switches have the advantages of small size, low energy consumption, stable performance, and easy adjustment. According to the different dimming mechanisms, liquid crystal optical switches can be divided into polarization type and non-polarization type. Polarization type liquid crystal optical switches usually include a pair of orthogonal polarizers, and switch the polarization direction of light by driving liquid crystal through an electric field. Due to the light absorption characteristics of the polarizer, the transmittance of polarization type liquid crystal optical switches to non-polarized light is low, and it is generally only used for regulating polarized light; non-polarization type liquid crystal optical switches do not contain polarizers and are non-polarization dependent dimming devices. Existing non-polarization type liquid crystal optical switches usually adopt the technical solution of polymer dispersed liquid crystal (PDLC), which includes a polymer liquid crystal layer. The liquid crystal is dispersed in the polymer in the form of droplets. When no electric field is applied, due to the refractive index difference between the liquid crystal droplets and the surrounding polymer, the incident light is scattered in the layer, and the polymer liquid crystal layer is in a scattering state (light-blocking state). Applying a suitable electric field can switch to a light-transmitting state. This solution can only increase the light-blocking rate by increasing the thickness of the PDLC layer. Increasing the thickness of the PDLC layer will not only lead to a significant increase in the driving voltage, but also reduce the transmittance after power is turned on. Summary of the invention

[0003] The purpose of the present invention is to provide an intensity-adjustable interface scattering liquid crystal optical switch and its working method. The present invention adjusts the transmittance by controlling the refractive index difference between the polymer layer and the liquid crystal layer to achieve the switching of the switch, and has the characteristics of low driving voltage and high transmittance.

[0004] The technical solution of the present invention is an intensity-adjustable interface scattering liquid crystal optical switch, comprising a liquid crystal layer, wherein polymer layers are respectively arranged on the upper and lower surfaces of the liquid crystal layer, a transparent electrode layer is arranged on the outer side of the polymer layer, and a transparent substrate is arranged on the outer side of the transparent electrode layer; the polymer layer serves as a rough interface of the liquid crystal layer.

[0005] In the above-mentioned intensity-adjustable interface scattering liquid crystal optical switch, the transparent substrate is transparent glass or a transparent flexible PET board.

[0006] In the aforementioned intensity-adjustable interface scattering liquid crystal optical switch, the transparent electrode layer is made of indium tin oxide.

[0007] In the aforementioned intensity-adjustable interface scattering liquid crystal optical switch, the polymer layer is made of a highly light-transmitting polymer.

[0008] In the aforementioned intensity-adjustable interface scattering liquid crystal optical switch, the highly light-transmitting polymer is polyvinyl chloride, polycarbonate or polypropylene.

[0009] In the aforementioned intensity-adjustable interface scattering liquid crystal optical switch, the liquid crystal layer is a positive nematic phase liquid crystal, the short-axis refractive index of the positive nematic phase liquid crystal is consistent with the refractive index of the rough surface polymer layer, and the long-axis refractive index of the positive nematic phase liquid crystal is greater than the refractive index of the rough surface polymer layer.

[0010] The aforementioned working method of an intensity-adjustable interface scattering liquid crystal optical switch is that when no voltage is applied to the transparent electrode layer, the liquid crystals of the liquid crystal layer are randomly oriented on the rough surface formed by the polymer layer, the refractive index of the liquid crystal layer is greater than the refractive index of the polymer layer, and the incident light is scattered and diffusely reflected on the rough surface of the polymer layer, presenting a light-blocking state; when a voltage is applied to the transparent electrode layer, the liquid crystals of the liquid crystal layer are oriented by the electric field, the refractive index of the liquid crystal layer approaches the refractive index of the polymer layer, the scattering and diffuse reflection effects of the incident light are gradually weakened, and finally a light-transmitting state is presented under a saturation voltage.

[0011] Compared with the prior art, the present invention adjusts the liquid crystal orientation of the liquid crystal layer by applying an electric field, and the refractive index changes accordingly. The changed refractive index forms a changing difference with the fixed refractive index of the rough surface polymer layer, thereby realizing the adjustment of the transmittance and completing the switching of the switch; structurally, the rough surfaces of the liquid crystal layer and the polymer layer of the present invention contact to form a scattering interface, and the liquid crystal of the traditional PDLC layer is distributed in the polymer layer in the form of droplets to form a scattering layer. Therefore, when working, the PDLC layer adjusts the transmittance in the form of interlayer scattering, and its light blocking rate and contrast depend on the thickness of the PDLC layer. Increasing the thickness will affect the range of action of the electric field and thus greatly affect the driving voltage, and also reduce the transmittance in the transparent state. The light blocking rate and contrast of the present invention depend on the surface roughness of the polymer layer and the refractive index difference with the liquid crystal layer. Increasing the roughness of the polymer layer and the refractive index difference with the liquid crystal layer can improve the light blocking rate and contrast without affecting the driving voltage; the present invention adjusts the transmittance by controlling the refractive index difference between the polymer layer and the liquid crystal layer to realize the switching of the switch, and has the characteristics of low driving voltage and high light transmittance. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a structural schematic diagram of the present invention.

[0013] The markings in the attached drawings are: 1. liquid crystal layer; 2. polymer layer; 3. transparent electrode layer; 4. transparent substrate. DETAILED DESCRIPTION

[0014] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0015] Embodiment: An intensity-adjustable interface scattering liquid crystal optical switch, as shown in the attached Figure 1 As shown, it includes a liquid crystal layer 1, and a polymer layer 2 is arranged on the upper and lower surfaces of the liquid crystal layer 1 respectively, and a transparent electrode layer 3 is arranged on the outer side of the polymer layer 2, and a transparent substrate 4 is arranged on the outer side of the transparent electrode layer 3; the polymer layer 2 serves as a rough interface with the liquid crystal layer 1, and the liquid crystal layer is in direct contact with the polymer layer, the polymer is solid, the liquid crystal is liquid, and the contact surface is a solid-liquid interface, and the incident light is scattered and diffusely reflected on this interface; the transparent electrode layer 3 forms an electric field when a voltage is applied to control the orientation of the liquid crystal molecules of the liquid crystal layer 1 to adjust the refractive index of the liquid crystal, thereby changing the refractive index difference between the polymer layer 2 and the liquid crystal layer 1, adjusting the transmittance, and completing the switching of the switch; the transparent substrate 4 is a transparent glass or a transparent flexible PET board with a thickness of several millimeters and has high transmittance; the transparent electrode 4 is formed on the transparent substrate 4 by high-temperature evaporation or magnetron sputtering of indium tin oxide with a thickness of several nanometers Layer 3 has conductivity and high transmittance; the transparent substrate 4 is spin-coated or hang-coated with a high-transmittance polymer solution, and the polymer layer 2 with a rough surface is formed after the solvent evaporates, and the roughness of the rough surface depends on the concentration and volatilization rate of the high-transmittance polymer solution. Increasing the volatilization rate can increase the roughness, and increasing the solution concentration can increase the roughness; in the polymer solution, the polymer is dissolved in an organic solvent as a solute and evenly distributed in the solution. The polymer coating formed by the solution applied on the transparent substrate after the solvent evaporates is evenly distributed, so that the roughness remains uniform; the high-transmittance polymer is polyvinyl chloride, polycarbonate or polypropylene; the liquid crystal layer 1 is a positive nematic phase liquid crystal, the short-axis refractive index of the positive nematic phase liquid crystal is consistent with the refractive index of the rough polymer layer 2, and the long-axis refractive index of the positive nematic phase liquid crystal is greater than the refractive index of the rough polymer layer 2.

[0016] A working method of an intensity-adjustable interface scattering liquid crystal optical switch, when no voltage is applied to the transparent electrode layer 3, the liquid crystals of the liquid crystal layer 1 are randomly oriented on the rough surface of the polymer layer 2, the refractive index of the liquid crystal layer 1 is greater than the refractive index of the polymer layer 2, the incident light is scattered and diffusely reflected on the rough interface, under the condition of a certain roughness of the rough surface, the greater the refractive index difference, the stronger the scattering and diffuse reflection effects, presenting a light-blocking effect to achieve a closing function; the transparent electrode layer 3 is applied with a voltage to form an electric field, the liquid crystals of the liquid crystal layer 1 are oriented by the electric field, as the voltage increases, the refractive index of the liquid crystal layer 1 approaches the refractive index of the polymer layer 2, the scattering and diffuse reflection effects of the incident light are weakened, gradually turning into a light-transmitting state, and finally completely transmitting light at a saturation voltage to achieve a switch-on function.

[0017] The above embodiments only express the implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. In this embodiment, the words "up", "down", "left", "right", "front" and "rear" only represent their relative positions and do not represent their absolute positions. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An intensity-adjustable interface scattering liquid crystal optical switch, characterized in that: The invention comprises a liquid crystal layer (1), wherein polymer layers (2) are respectively arranged on the upper and lower surfaces of the liquid crystal layer (1), a transparent electrode layer (3) is arranged on the outer side of the polymer layer (2), and a transparent substrate (4) is arranged on the outer side of the transparent electrode layer (3); the polymer layer (2) serves as a rough interface of the liquid crystal layer (1).

2. The intensity-adjustable interface scattering liquid crystal optical switch according to claim 1, characterized in that: The transparent substrate (4) is transparent glass or a transparent flexible PET board.

3. The intensity-adjustable interface scattering liquid crystal optical switch according to claim 1, characterized in that: The material of the transparent electrode layer (3) is indium tin oxide.

4. The intensity-adjustable interface scattering liquid crystal optical switch according to claim 1, characterized in that: The material of the polymer layer (2) is a highly light-transmitting polymer.

5. The intensity-adjustable interface scattering liquid crystal optical switch according to claim 4, characterized in that: The highly light-transmitting polymer is polyvinyl chloride, polycarbonate or polypropylene.

6. The intensity-adjustable interface scattering liquid crystal optical switch according to claim 1, characterized in that: The liquid crystal layer (1) is a positive nematic liquid crystal, the short-axis refractive index of the positive nematic liquid crystal is consistent with the refractive index of the rough-surface polymer layer (2), and the long-axis refractive index of the positive nematic liquid crystal is greater than the refractive index of the rough-surface polymer layer (2).

7. The working method of the intensity-adjustable interface scattering liquid crystal optical switch according to any one of claims 1 to 6, characterized in that: When no voltage is applied to the transparent electrode layer (3), the liquid crystals of the liquid crystal layer (1) are randomly oriented on the rough surface formed by the polymer layer (2), the refractive index of the liquid crystal layer (1) is greater than the refractive index of the polymer layer, and incident light is scattered and diffusely reflected on the rough surface formed by the polymer layer (2), presenting a light-blocking state; when a voltage is applied to the transparent electrode layer (3), the liquid crystals of the liquid crystal layer (1) are oriented by the electric field, the refractive index of the liquid crystal layer (1) approaches the refractive index of the polymer layer (2), the scattering and diffuse reflection effects of the incident light are gradually weakened, and finally a light-transmitting state is presented at a saturated voltage.

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