Polarization-independent light modulator based on special optical axis design and preparation method thereof

Abstract

The invention discloses a polarization-independent optical modulator based on special optical axis design and a preparation method thereof. The preparation method comprises the following steps: S1, selecting a low-resistance electrode substrate with a reflection function to form a high-quality reflection electrode substrate; s2, coating the reflection electrode substrate with an orientation material to form an orientation layer, and enabling the molecular orientation direction of the orientation layer and the substrate surface to form an initial angle; s3, integrating a phase delay optical element on the orientation layer; s4, adding a liquid molecular material with an orientation characteristic into the phase delay optical element to form a liquid dielectric layer; s5, performing orientation control on the liquid dielectric layer through an external orientation field to obtain a half device; by designing and controlling the orientation angle relation among the orientation layer, the phase delay optical element and the liquid medium layer, it is ensured that when light passes through the device, the consistent phase modulation effect can be obtained regardless of the polarization state of the light, the polarization independence of the light modulator is achieved, and the optical performance of the device is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical devices, and in particular to a polarization-independent optical modulator based on a special optical axis design and a preparation method thereof. Background Art

[0002] As an important optical device, liquid crystal spatial light modulator (SLM) is widely used in laser processing, optical communication, holographic display, optical computing and adaptive optics. In these applications, SLM precisely modulates the phase or amplitude of the incident light to control the spatial distribution and characteristics of the light field. With the rapid development of optoelectronic technology, the demand for SLM in terms of high resolution, high speed and high precision is growing, especially in high-end fields such as ultrafast laser processing and high-definition holographic display, which puts higher requirements on the performance of SLM.

[0003] Existing liquid crystal spatial light modulators usually use silicon-based liquid crystal materials. By sandwiching an orientation layer and a liquid crystal layer between the upper and lower electrodes, the orientation of the liquid crystal molecules is controlled by an electric field, thereby achieving phase modulation of light. However, this traditional structure of SLM is often sensitive to the polarization state of the incident light. The main reason is that the anisotropy of the liquid crystal molecules makes the phase modulation effect of the device closely related to the polarization direction of the light. This polarization dependence causes the optical performance of the device to change when the polarization state of the incident light changes, affecting the consistency and stability of the SLM in practical applications.

[0004] Therefore, how to realize a liquid crystal spatial light modulator that is independent of the polarization state of the incident light has become an urgent problem to be solved in the current technical field. Summary of the invention

[0005] The purpose of the present invention is to provide a polarization-independent optical modulator based on a special optical axis design and a preparation method to solve the above technical problems.

[0006] To achieve this object, the present invention adopts the following technical solutions: A method for preparing a polarization-independent optical modulator based on a special optical axis design, comprising: Step S1: Select a low-resistance electrode substrate with a reflective function, and process its surface to form a high-quality reflective electrode substrate; Step S2: coating an alignment material on the reflective electrode substrate to form an alignment layer, and patterning the alignment layer using a micro-nano structure template method so that the molecular alignment direction of the alignment layer forms an initial angle with the substrate surface; Step S3: placing a customized anisotropic film as a phase-delay optical element on the alignment layer; the optical axis direction of the phase-delay optical element and the molecular alignment direction of the alignment layer form a preset first angle; Step S4: adding a liquid molecular material having an orientation characteristic to the phase delay optical element to form a liquid medium layer; Step S5: Orienting the liquid medium layer by applying an external directional field so that the angle between the long axis of its molecules and the optical axis of the phase delay optical element is a preset target angle, thereby obtaining a semi-device; wherein the target angle = initial angle + first angle.

[0007] Optionally, the step S1 specifically includes: Step S11: selecting a metal base material with low resistivity and excellent reflective performance, wherein the metal base material is high-purity silver or aluminum material; Step S12: using an organic solvent to ultrasonically clean the metal base material, and then performing a surface polishing process; Step S13: using a plasma cleaning method to treat the surface of the metal base material in argon plasma for 5 minutes to remove the oxide layer and residual pollutants, and at the same time to activate the surface of the metal base material; Step S14: placing the metal substrate material into a vacuum evaporation device, and depositing a metal film with a thickness of 100-200 nanometers by thermal evaporation of silver or aluminum under high vacuum conditions to form a reflective electrode substrate with a high reflective electrode layer.

[0008] Optionally, the step S2 specifically includes: Step S21: uniformly coating an alignment material on the reflective electrode substrate, wherein the alignment material is polyimide or a photosensitive alignment material, and the coating thickness is 50-100 nanometers; Step S22: pre-baking the reflective electrode substrate coated with the alignment material at a temperature of 80° C. for 10 minutes to preliminarily solidify the alignment layer; Step S23: patterning the alignment layer using a micro-nano structure template method, wherein the micro-nano structure template has a periodic microstructure, and the template pattern is transferred to the surface of the alignment layer using ultraviolet lithography technology.

[0009] Optionally, after step S23, the following steps are further included: Step S24: performing a main baking treatment on the patterned alignment layer at a temperature of 200° C. for 30 minutes to completely solidify the alignment layer and maintain the pattern structure; Step S25: performing a friction orientation treatment on the surface of the orientation layer, using an orientation cloth to rub along a specific direction at a constant pressure and speed, so that the molecular orientation direction of the orientation layer forms an initial angle with the substrate surface, and the initial angle is 5°.

[0010] Optionally, the step S3 specifically includes: Step S31: Select an anisotropic film made of liquid crystal polymer or quartz single crystal to cut the film, and the thickness of the obtained phase delay optical element is precisely controlled within the range of 1-5 microns; Step S32: using a polarization interferometer to measure the optical axis direction of the phase delay optical element; Step S33: fix the reflective electrode substrate with the alignment layer on a rotating workbench so that the molecular alignment direction of the alignment layer is consistent with a preset reference direction.

[0011] Optionally, after step S33, the following steps are further included: Step S34: according to the design requirements, a first angle θ1 between the optical axis direction of the phase delay optical element and the molecular orientation direction of the orientation layer is set, and the rotary table is operated to adjust the angle of the orientation layer substrate so that the orientation direction forms a first angle θ1 with the preset reference direction; Step S35: using an optical grade transparent adhesive to evenly apply a layer of glue between the phase delay optical element and the alignment layer to form a bonding assembly; Step S36: Clean the adhesive assembly to remove adhesive and impurities remaining on the surface.

[0012] Optionally, the step S5 specifically includes: Step S51: establishing an external orientation field device for orientation, wherein the orientation field may be an electric field or a magnetic field; The electric field orientation is as follows: connecting electrodes at both ends of the bonding assembly so that the electrodes are in contact with the liquid medium layer to perform electric field orientation; Wherein, the magnetic field orientation is: if the magnetic field orientation is used, an electromagnetic coil is arranged outside the bonding component to generate a uniform magnetic field for electric field orientation; the magnetic field strength can be adjusted within a range of 0-1 Tesla; Step S52: filling the liquid molecular material into the liquid crystal cavity in the bonding component by capillary action; Step S53: after the liquid molecular material is filled, applying an external directional field to the bonding component filled with the liquid medium layer; For electric field orientation: a constant voltage is applied for 15 minutes, with the electric field direction perpendicular to the plane of the liquid medium layer, so that the liquid crystal molecules are oriented along the electric field direction; For magnetic field orientation: a constant magnetic field is applied, the direction of the magnetic field forms a preset target angle θ0 with the optical axis direction of the phase delay optical element, and the duration is 15 minutes, so that the liquid crystal molecules are oriented under the action of the magnetic field.

[0013] Optionally, after step S53, the following steps are further included: Step S54: After the external aligning field is applied, the aligning field is kept applied and the component temperature is lowered to room temperature to fix the alignment state of the liquid crystal molecules; Step S55: Use a polarizing microscope to detect the orientation direction of the liquid crystal molecules in the liquid crystal layer, and determine the long axis direction of the liquid crystal molecules by observing the extinction position, so that the angle between the long axis of the liquid crystal molecules and the optical axis of the phase delay optical element is a preset target angle θ0, and satisfies θ0=initial angle+first angle θ1.

[0014] Optionally, after step S5, the following steps may be further performed: Step S6: attaching the transparent upper substrate to the half device, aligning and assembling, using a gap control material to control the thickness of the liquid medium layer, and sealing the edge of the device to form a polarization-independent light modulator.

[0015] The present invention further provides a polarization-independent optical modulator based on a special optical axis design, which is manufactured using the method for manufacturing a polarization-independent optical modulator based on a special optical axis design as described above, and the polarization-independent optical modulator comprises: A reflective electrode substrate is prepared by treating the surface of a low-resistance electrode substrate having a reflective function; An alignment layer is coated on the reflective electrode substrate and patterned using a micro-nano structure template method; A phase delay optical element is stacked on the alignment layer, and the optical axis direction thereof forms a preset first angle with the molecular alignment direction of the alignment layer; The liquid medium layer is formed by filling a liquid molecular material having an orientation characteristic on the phase delay optical element; The packaging layer is arranged on the peripheral side of the device and is used to seal the polarization-independent optical modulation device.

[0016] Compared with the prior art, the present invention has the following beneficial effects: a low-resistance electrode substrate with a reflective function is selected and its surface is processed, an orientation material is coated on the reflective electrode substrate to form an orientation layer, a micro-nano structure template method is used to pattern the orientation layer so that the molecular orientation direction of the orientation layer forms an initial angle with the substrate surface, a customized anisotropic film is placed on the orientation layer as a phase delay optical element, and the optical axis direction of the phase delay optical element and the molecular orientation direction of the orientation layer are at a preset first angle; a liquid molecular material with orientation characteristics is added to the phase delay optical element to form a liquid medium layer, and the orientation of the liquid medium layer is controlled by an external orientation field so that the angle between the molecular long axis and the optical axis of the phase delay optical element reaches a preset target angle, thereby obtaining a semi-device; wherein the target angle is equal to the sum of the initial angle and the first angle; by designing and controlling the orientation angle relationship between the orientation layer, the phase delay optical element and the liquid medium layer, the scheme ensures that when light passes through the device, regardless of its polarization state, a consistent phase modulation effect can be obtained, thereby realizing the polarization independence of the optical modulator and improving the optical performance of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical contents disclosed by the present invention.

[0019] Figure 1 This is one of the schematic flow diagrams of the preparation method of Example 1; Figure 2 This is the second schematic flow diagram of the preparation method of Example 1. DETAILED DESCRIPTION

[0020] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] In the description of the present invention, it should be understood that the terms "upper", "lower", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. It should be noted that when a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally arranged component at the same time.

[0022] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0023] Embodiment 1: Combination Figure 1 to Figure 2 As shown, an embodiment of the present invention provides a method for preparing a polarization-independent optical modulator based on a special optical axis design, comprising: Step S1: Select a low-resistance electrode substrate with a reflective function, and process its surface to form a high-quality reflective electrode substrate; Select a low-resistance electrode substrate with reflective function and treat its surface to form a high-quality reflective electrode substrate. The purpose of this step is to ensure that the substrate has excellent electrical conductivity and optical reflection properties. By carefully cleaning, polishing and treating the substrate surface, removing impurities and oxide layers, a clean, smooth and highly reflective electrode surface is obtained.

[0024] Step S2: coating an alignment material on the reflective electrode substrate to form an alignment layer, and patterning the alignment layer using a micro-nano structure template method so that the molecular alignment direction of the alignment layer forms an initial angle with the substrate surface; An orientation material is coated on the reflective electrode substrate to form an orientation layer. Then, the orientation layer is patterned using a micro-nano structure template method so that the molecular orientation direction of the orientation layer forms an initial angle with the substrate surface. The key to this step is to guide the arrangement direction of the molecules in the subsequent liquid medium layer by precisely controlling the pattern and molecular orientation angle of the orientation layer. The initial angle setting of the orientation layer is conducive to achieving the predetermined orientation of the liquid crystal molecules and optimizing the optical performance.

[0025] Step S3: placing a customized anisotropic film as a phase-delay optical element on the alignment layer; the optical axis direction of the phase-delay optical element and the molecular alignment direction of the alignment layer form a preset first angle; By precisely setting the relationship between the optical axis and the orientation direction, the phase delay effect of light in the device is controlled. The addition of phase delay optical elements and angle setting are the key to achieving polarization-independent light modulation, ensuring that the device has consistent modulation performance for light in different polarization states.

[0026] Step S4: Add liquid molecular materials with orientation characteristics to the phase delay optical element to form a liquid medium layer; the liquid molecular material can be positive liquid crystal or negative liquid crystal. The appropriate liquid crystal type is selected according to the application requirements to ensure that the liquid crystal material is high in purity and free of impurities and moisture. The liquid crystal material is placed in a vacuum drying oven and kept at 60°C for 12 hours to remove residual moisture.

[0027] Step S5: Orienting the liquid medium layer by applying an external directional field so that the angle between the long axis of its molecules and the optical axis of the phase delay optical element is a preset target angle, thereby obtaining a half device; wherein the target angle = the initial angle + the first angle.

[0028] By precisely controlling the orientation angle of the liquid crystal molecules, the optical path and phase delay characteristics of the device are ensured to meet the design requirements. The application of an external directional field and the control of the orientation process are key steps to achieve orderly arrangement of liquid crystal molecules and polarization-independent modulation performance.

[0029] The working principle of the present invention is as follows: a low-resistance electrode substrate with a reflective function is selected and its surface is processed, an orientation material is coated on the reflective electrode substrate to form an orientation layer, a micro-nano structure template method is used to pattern the orientation layer so that the molecular orientation direction of the orientation layer forms an initial angle with the substrate surface, a customized anisotropic film is used as a phase delay optical element and is placed on the orientation layer, and the optical axis direction of the phase delay optical element and the molecular orientation direction of the orientation layer are at a preset first angle; a liquid molecular material with orientation characteristics is added to the phase delay optical element to form a liquid medium layer, and the orientation of the liquid medium layer is controlled by an external orientation field so that the angle between the molecular long axis and the optical axis of the phase delay optical element reaches a preset target angle, thereby obtaining a semi-device; wherein the target angle is equal to the sum of the initial angle and the first angle; by designing and controlling the orientation angle relationship between the orientation layer, the phase delay optical element and the liquid medium layer, the scheme ensures that when light passes through the device, regardless of its polarization state, a consistent phase modulation effect can be obtained, thereby realizing the polarization independence of the optical modulator and improving the optical performance of the device.

[0030] In this embodiment, it is specifically explained that step S1 specifically includes: Step S11: selecting a metal base material with low resistivity and excellent reflective performance, wherein the metal base material is high-purity silver or aluminum material; This is because both silver and aluminum have extremely low resistivity, providing excellent electrical conductivity and facilitating the efficient transmission of electrical signals. In addition, they exhibit extremely high reflectivity in the visible and infrared ranges, making them ideal reflective electrode materials. High-purity metal materials reduce the impact of impurities and ensure that the electrical and optical properties of the base material are optimal.

[0031] Step S12: using an organic solvent to ultrasonically clean the metal base material, and then performing a surface polishing process; First, use organic solvents (such as acetone, anhydrous ethanol) to ultrasonically clean the metal substrate material. Ultrasonic cleaning uses the cavitation effect generated by ultrasound in the solvent to efficiently remove grease, organic matter and tiny particles on the substrate surface to ensure the cleanliness of the surface. After cleaning, the substrate surface is mechanically polished. By using polishing liquids and polishing pads of different particle sizes, from rough polishing to fine polishing, the surface roughness is gradually reduced to obtain a smooth surface.

[0032] Step S13: using a plasma cleaning method to treat the surface of the metal base material in argon plasma for 5 minutes to remove the oxide layer and residual pollutants, and at the same time to activate the surface of the metal base material; Plasma cleaning technology is used to treat the surface of metal substrate materials. The cleaned and polished substrate is placed in a plasma cleaning device and argon gas is introduced to generate argon plasma. Under the bombardment of argon plasma, the oxide layer and residual organic pollutants on the surface of the substrate are effectively removed. The treatment time is set to 5 minutes to ensure thorough cleaning without damaging the substrate surface. At the same time, plasma treatment can also activate the substrate surface and increase its surface energy. This surface activation helps the subsequent deposition of metal films and improves the adhesion between the film and the substrate.

[0033] Step S14: placing the metal substrate material into a vacuum evaporation device, and depositing a metal film with a thickness of 100-200 nanometers by thermal evaporation of silver or aluminum under high vacuum conditions to form a reflective electrode substrate with a high reflective electrode layer.

[0034] The cleaned and activated metal substrate material is placed in a vacuum evaporation device. By evacuating the device, a high vacuum state is achieved to reduce the interference of gas molecules on the evaporation process. The silver or aluminum is heated by thermal evaporation to evaporate into gas phase atoms or molecules at high temperature. These vapors move linearly in a vacuum and deposit on the substrate surface to form a dense and uniform metal film. By precisely controlling the evaporation time and evaporation rate, the thickness of the film is adjusted to a range of 100-200 nanometers. This thickness range not only ensures the continuity and conductivity of the reflective electrode layer, but also avoids stress and material waste caused by excessive thickness. Finally, a reflective electrode substrate with high reflectivity and good electrical properties is formed.

[0035] In this embodiment, it is specifically described that step S2 specifically includes: Step S21: uniformly coating an alignment material on the reflective electrode substrate, wherein the alignment material is polyimide or a photosensitive alignment material, and the coating thickness is 50-100 nanometers; The orientation material uses polyimide (PI) or photosensitive orientation material, which has good thermal stability and electrical insulation, and is suitable for the orientation control of liquid crystal molecules. The coating thickness is precisely controlled within the range of 50-100 nanometers to ensure that the orientation layer has sufficient mechanical strength and is not too thick to affect the optical performance.

[0036] Step S22: pre-baking the reflective electrode substrate coated with the alignment material at a temperature of 80° C. for 10 minutes to preliminarily solidify the alignment layer; The substrate coated with the alignment material is placed in an oven for pre-baking (soft baking) at 80°C for 10 minutes. The purpose of pre-baking is to remove the solvent in the alignment material, preliminarily solidify the alignment layer, and increase its mechanical stability. This process helps prevent the alignment layer from flowing or deforming during subsequent processing (such as photolithography or friction).

[0037] Step S23: patterning the alignment layer using a micro-nano structure template method, the micro-nano structure template has a periodic microstructure, and the template pattern is transferred to the alignment layer surface using ultraviolet lithography technology.

[0038] The alignment layer is patterned using a micro-nano structure template with a periodic microstructure. The micro-nano pattern on the template is accurately transferred to the surface of the alignment layer through ultraviolet lithography. The specific operation is to place the template close to the alignment layer and irradiate it with ultraviolet light so that the photosensitive alignment material undergoes a chemical reaction in the exposed area, changing its alignment properties. The unexposed area retains its original properties. For non-photosensitive alignment materials, the pattern transfer can be achieved by combining the etching process. The patterned alignment layer can control the alignment direction of the liquid crystal molecules on a microscopic scale, improving the spatial resolution and optical performance of the device.

[0039] Step S24: performing a main baking treatment on the patterned alignment layer at a temperature of 200° C. for 30 minutes to completely solidify the alignment layer and maintain the pattern structure; The patterned alignment layer is subjected to main baking (hard baking) with the temperature raised to 200°C for 30 minutes. The purpose of the main baking is to fully solidify the alignment layer, further enhance its mechanical strength and heat resistance, and stabilize and fix the formed pattern structure. High temperature treatment can increase the degree of polymerization of the alignment material, forming a dense film to avoid deformation or damage in subsequent processes. Accurately control the main baking temperature and time to ensure the optimization of the alignment layer performance and the complete retention of the pattern.

[0040] Step S25: performing a friction orientation treatment on the surface of the orientation layer, using an orientation cloth to rub along a specific direction at a constant pressure and speed, so that the molecular orientation direction of the orientation layer forms an initial angle of 5° with the substrate surface.

[0041] The surface of the solidified alignment layer is subjected to friction alignment treatment. Use a special alignment cloth (such as velvet cloth or flocking cloth) to rub the alignment layer surface in a specific direction at a constant pressure and speed. The rubbing process produces uniform micro grooves on the surface of the alignment layer, which guide the liquid crystal molecules to align along the rubbing direction on the contact surface. By adjusting the angle of the rubbing device, the movement direction of the alignment cloth forms an initial angle of 5° with the substrate surface. This initial angle (pretilt angle) is crucial for the tilted alignment of the liquid crystal molecules, which helps prevent the liquid crystal molecules from being vertically aligned or distorted, improves the alignment uniformity and stability of the liquid crystal layer, and thus improves the performance of the light modulator.

[0042] In this embodiment, it is specifically described that step S3 specifically includes: Step S31: Select an anisotropic film made of liquid crystal polymer or quartz single crystal to cut the film, and the thickness of the obtained phase delay optical element is precisely controlled within the range of 1-5 microns; First, liquid crystal polymer or quartz single crystal is selected as the material. These materials have excellent optical anisotropy and are suitable for making phase delay optical elements. Using precise thin film cutting technology, the material is processed into a film with a thickness in the range of 1-5 microns. Accurate control of thickness is crucial to the phase delay effect, because the thickness of the film directly affects the amount of phase delay of light in it. Films that are too thick or too thin will cause the phase delay to deviate from the design value, thereby affecting the performance of the optical modulator. Therefore, the process parameters need to be strictly controlled during the processing to ensure that the thickness meets the design requirements.

[0043] Step S32: using a polarization interferometer to measure the optical axis direction of the phase delay optical element; Polarized light interferometer is used to measure the direction of the optical axis of the processed phase-delay optical element. Polarized light interferometer is a precision optical measuring instrument that can accurately measure the birefringence characteristics and optical axis direction of optical materials. By placing the phase-delay optical element in the interferometer, rotating the sample and observing the changes in the interference fringes, the position where the interference fringes are clearest or disappear is found, thereby determining the precise direction of the optical axis.

[0044] Step S33: fixing the reflective electrode substrate with the orientation layer on a rotating workbench so that the molecular orientation direction of the orientation layer is consistent with a preset reference direction; The previously prepared reflective electrode substrate with an orientation layer is placed and fixed on a high-precision rotating table. First, the molecular orientation direction of the orientation layer is aligned with a preset reference direction (such as horizontal or vertical direction) through a microscope and a marking line. The purpose of this step is to provide a reference for subsequent angle adjustments so that the direction of the orientation layer can form a precise angle with the optical axis direction of the phase delay optical element. When fixing the substrate, it is necessary to ensure that it is stable and does not move to maintain the precise angle setting.

[0045] Step S34: according to the design requirements, a first angle θ1 between the optical axis direction of the phase delay optical element and the molecular orientation direction of the orientation layer is set, and the rotary table is operated to adjust the angle of the orientation layer substrate so that the orientation direction forms a first angle θ1 with the preset reference direction; According to the design requirements, the first angle θ1 (for example, 45°) to be achieved is determined. Subsequently, the angle of the orientation layer substrate is precisely adjusted by rotating the workbench so that the molecular orientation direction of the orientation layer forms an angle of θ1 relative to the preset reference direction. This operation ensures that when the optical axis direction of the phase delay optical element is fixed in the reference direction, the angle between the two is the θ1 required by the design.

[0046] Step S35: using an optical grade transparent adhesive to evenly apply a layer of glue between the phase delay optical element and the alignment layer to form a bonding assembly; In step S35, an optical grade transparent adhesive (such as UV curing adhesive or heat curing adhesive) is selected to evenly apply a layer of glue between the phase delay optical element and the surface of the orientation layer. The coating of the adhesive needs to ensure uniform thickness, free of bubbles and impurities, so as not to affect the optical performance. Then, the phase delay optical element is gently placed on the orientation layer, and ensure that the direction of its optical axis is consistent with the preset reference direction. Since the angle of the orientation layer substrate has been adjusted before, the angle between the two has reached θ1. During the bonding process, it is necessary to keep the elements aligned and positioned to avoid sliding or misalignment. Finally, the adhesive is cured by an appropriate curing method (such as UV irradiation or heating) to form a stable bonded assembly.

[0047] Step S36: Clean the adhesive assembly to remove adhesive and impurities remaining on the surface.

[0048] Thoroughly clean the components that have been bonded. During the bonding process, a small amount of adhesive may overflow onto the surface or edge of the component, or tiny dust particles may be attached.

[0049] In this embodiment, it is specifically described that step S5 specifically includes: Step S51: establishing an external orientation field device for orientation, where the orientation field can be an electric field or a magnetic field; The electric field orientation is as follows: connecting electrodes at both ends of the bonding assembly so that the electrodes are in contact with the liquid medium layer to perform electric field orientation; Among them, the magnetic field orientation is: if magnetic field orientation is used, an electromagnetic coil is set outside the bonding component to generate a uniform magnetic field for electric field orientation; the adjustable range of magnetic field strength is between 0-1 Tesla.

[0050] Step S52: Fill the liquid molecular material into the liquid crystal cavity in the bonding component by capillary action; specifically: place the bonding component on a vacuum liquid injection table, reduce the pressure to -0.1 MPa, open the injection port of the liquid molecular material, and allow the liquid molecular material to fill into the liquid crystal cavity under the action of the pressure difference.

[0051] Step S53: after the liquid molecular material is filled, applying an external directional field to the bonding component filled with the liquid medium layer; For electric field orientation: a constant voltage is applied for 15 minutes, with the electric field direction perpendicular to the plane of the liquid medium layer, so that the liquid crystal molecules are oriented along the electric field direction; For magnetic field orientation: a constant magnetic field is applied, the direction of the magnetic field forms a preset target angle θ0 with the optical axis direction of the phase delay optical element, and the duration is 15 minutes, so that the liquid crystal molecules are oriented under the action of the magnetic field.

[0052] In this embodiment, it is further explained that after step S53, the following steps are further included: Step S54: After the external aligning field is applied, the aligning field is kept applied and the component temperature is lowered to room temperature to fix the alignment state of the liquid crystal molecules; Maintaining the orientation field: During the temperature reduction process, the electric or magnetic field is continuously applied to prevent the liquid crystal molecules from aligning and becoming disordered during the temperature change.

[0053] Temperature reduction: By controlling the cooling rate, the temperature of the component is gradually reduced from the operating temperature to room temperature. The cooling process needs to be smooth to avoid thermal stress affecting the device.

[0054] Orientation fixation: As the temperature decreases, the viscosity of the liquid crystal material increases, the mobility of the molecules decreases, and the orientation state of the liquid crystal molecules is fixed. This step ensures the stability of the liquid crystal molecular orientation and provides guarantee for the long-term reliable operation of the device.

[0055] Step S55: Use a polarizing microscope to detect the orientation direction of the liquid crystal molecules in the liquid crystal layer, and determine the long axis direction of the liquid crystal molecules by observing the extinction position, so that the angle between the long axis of the liquid crystal molecules and the optical axis of the phase delay optical element is a preset target angle θ0, and satisfies θ0=initial angle + first angle θ1 in step S34.

[0056] Using a polarizing microscope: The components after orientation and cooling are observed under a polarizing microscope.

[0057] Observe the extinction position: Observe the changes in brightness and darkness in the field of view by rotating the assembly. When the long axis direction of the liquid crystal molecules is perpendicular to the vibration direction of the polarizer, obvious extinction will occur (the field of view becomes darker), and record the angle corresponding to the extinction position.

[0058] Determine the orientation direction: Determine the orientation direction of the long axis of the liquid crystal molecules based on the extinction position.

[0059] Verify the angle: Calculate the actual angle between the long axis of the liquid crystal molecules and the optical axis of the phase delay optical element to confirm whether it is equal to the preset target angle θ0.

[0060] Satisfy the relationship: Ensure that the target angle θ0 satisfies θ0 = initial angle (tilt angle of the alignment layer) + first angle θ1 (angle between the phase delay optical element and the alignment layer) to verify the accuracy of the alignment process.

[0061] In this embodiment, it is further explained that after step S5, the following steps are further included: Step S6: attaching the transparent upper substrate to the half device, aligning and assembling, using a gap control material to control the thickness of the liquid medium layer, and sealing the edge of the device to form a polarization-independent light modulator.

[0062] Bonding transparent upper substrate: Use a transparent substrate with high light transmittance (such as quartz glass or glass coated with a transparent conductive film) as the upper substrate.

[0063] Alignment assembly: Precisely align the transparent upper substrate with the semi-device (including the reflective electrode substrate, alignment layer, phase delay optical element and liquid medium layer) to ensure optical alignment between the layers and achieve optimal optical performance.

[0064] Gap control: Add spacers (such as micron-sized spacer balls or support structures formed by photolithography) between the upper and lower substrates to accurately control the thickness of the liquid medium layer (liquid crystal layer). Thickness uniformity is critical to the phase modulation performance of liquid crystal devices.

[0065] Edge sealing treatment: Coat the edge of the device with sealing materials such as UV curing glue or epoxy resin to seal the liquid crystal layer to prevent leakage of liquid crystal materials and entry of external contaminants.

[0066] Embodiment 2: The present invention further provides a polarization-independent optical modulator based on a special optical axis design, which is manufactured using the method for manufacturing a polarization-independent optical modulator based on a special optical axis design as in Embodiment 1. The polarization-independent optical modulator includes: The reflective electrode substrate is prepared by treating the surface of a low-resistance electrode substrate with a reflective function.

[0067] The orientation layer is coated on the reflective electrode substrate and patterned by using a micro-nano structure template method.

[0068] The phase delay optical element is stacked on the alignment layer, and the optical axis direction of the phase delay optical element forms a preset first angle with the molecular alignment direction of the alignment layer.

[0069] The liquid medium layer is formed by filling a liquid molecular material with orientation characteristics on the phase delay optical element.

[0070] The packaging layer is arranged on the peripheral side of the device and is used to seal the polarization-independent optical modulation device.

[0071] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a polarization-independent optical modulator based on a special optical axis design, characterized in that: include: Step S1: Select a low-resistance electrode substrate with a reflective function, and process its surface to form a high-quality reflective electrode substrate; Step S2: coating an alignment material on the reflective electrode substrate to form an alignment layer, and patterning the alignment layer using a micro-nano structure template method so that the molecular alignment direction of the alignment layer forms an initial angle with the substrate surface; Step S3: placing a customized anisotropic film as a phase-delay optical element on the alignment layer; the optical axis direction of the phase-delay optical element and the molecular alignment direction of the alignment layer form a preset first angle; Step S4: adding a liquid molecular material having an orientation characteristic to the phase delay optical element to form a liquid medium layer; Step S5: Orienting the liquid medium layer by applying an external directional field so that the angle between the long axis of its molecules and the optical axis of the phase delay optical element is a preset target angle, thereby obtaining a semi-device; wherein the target angle = initial angle + first angle.

2. The method for preparing a polarization-independent optical modulator based on a special optical axis design according to claim 1, characterized in that: The step S1 specifically includes: Step S11: selecting a metal base material with low resistivity and excellent reflective performance, wherein the metal base material is high-purity silver or aluminum material; Step S12: using an organic solvent to ultrasonically clean the metal base material, and then performing a surface polishing process; Step S13: using a plasma cleaning method to treat the surface of the metal base material in argon plasma for 5 minutes to remove the oxide layer and residual pollutants, and at the same time to activate the surface of the metal base material; Step S14: placing the metal substrate material into a vacuum evaporation device, and depositing a metal film with a thickness of 100-200 nanometers by thermal evaporation of silver or aluminum under high vacuum conditions to form a reflective electrode substrate with a high reflective electrode layer.

3. The method for preparing a polarization-independent optical modulator based on a special optical axis design according to claim 1, characterized in that: The step S2 specifically includes: Step S21: uniformly coating an alignment material on the reflective electrode substrate, wherein the alignment material is polyimide or a photosensitive alignment material, and the coating thickness is 50-100 nanometers; Step S22: pre-baking the reflective electrode substrate coated with the alignment material at a temperature of 80° C. for 10 minutes to preliminarily solidify the alignment layer; Step S23: patterning the alignment layer using a micro-nano structure template method, wherein the micro-nano structure template has a periodic microstructure, and the template pattern is transferred to the surface of the alignment layer using ultraviolet lithography technology.

4. The method for preparing a polarization-independent optical modulator based on a special optical axis design according to claim 1, characterized in that: After step S23, the following steps are also included: Step S24: performing a main baking treatment on the patterned alignment layer at a temperature of 200° C. for 30 minutes to completely solidify the alignment layer and maintain the pattern structure; Step S25: performing a friction orientation treatment on the surface of the orientation layer, using an orientation cloth to rub along a specific direction at a constant pressure and speed, so that the molecular orientation direction of the orientation layer forms an initial angle with the substrate surface, and the initial angle is 5°.

5. The method for preparing a polarization-independent optical modulator based on a special optical axis design according to claim 1, characterized in that: The step S3 specifically includes: Step S31: Select an anisotropic film made of liquid crystal polymer or quartz single crystal to cut the film, and the thickness of the obtained phase delay optical element is precisely controlled within the range of 1-5 microns; Step S32: using a polarization interferometer to measure the optical axis direction of the phase delay optical element; Step S33: fix the reflective electrode substrate with the alignment layer on a rotating workbench so that the molecular alignment direction of the alignment layer is consistent with a preset reference direction.

6. The method for preparing a polarization-independent optical modulator based on a special optical axis design according to claim 5, characterized in that: After step S33, the following steps are also included: Step S34: according to the design requirements, a first angle θ1 between the optical axis direction of the phase delay optical element and the molecular orientation direction of the orientation layer is set, and the rotary table is operated to adjust the angle of the orientation layer substrate so that the orientation direction forms a first angle θ1 with the preset reference direction; Step S35: using an optical grade transparent adhesive to evenly apply a layer of glue between the phase delay optical element and the alignment layer to form a bonding assembly; Step S36: Clean the adhesive assembly to remove adhesive and impurities remaining on the surface.

7. The method for preparing a polarization-independent optical modulator based on a special optical axis design according to claim 6, characterized in that: The step S5 specifically includes: Step S51: establishing an external orientation field device for orientation, wherein the orientation field may be an electric field or a magnetic field; The electric field orientation is as follows: connecting electrodes at both ends of the bonding assembly so that the electrodes are in contact with the liquid medium layer to perform electric field orientation; Wherein, the magnetic field orientation is: if the magnetic field orientation is used, an electromagnetic coil is arranged outside the bonding component to generate a uniform magnetic field for electric field orientation; the magnetic field intensity can be adjusted within a range of 0-1 Tesla; Step S52: filling the liquid molecular material into the liquid crystal cavity in the bonding component by capillary action; Step S53: after the liquid molecular material is filled, applying an external directional field to the bonding component filled with the liquid medium layer; For electric field orientation: a constant voltage is applied for 15 minutes, with the electric field direction perpendicular to the plane of the liquid medium layer, so that the liquid crystal molecules are oriented along the electric field direction; For magnetic field orientation: a constant magnetic field is applied, the direction of the magnetic field forms a preset target angle θ0 with the optical axis direction of the phase delay optical element, and the duration is 15 minutes, so that the liquid crystal molecules are oriented under the action of the magnetic field.

8. The method for preparing a polarization-independent optical modulator based on a special optical axis design according to claim 7, characterized in that: After step S53, the following steps are further included: Step S54: After the external aligning field is applied, the aligning field is kept applied and the component temperature is lowered to room temperature to fix the alignment state of the liquid crystal molecules; Step S55: Use a polarizing microscope to detect the orientation direction of the liquid crystal molecules in the liquid crystal layer, and determine the long axis direction of the liquid crystal molecules by observing the extinction position, so that the angle between the long axis of the liquid crystal molecules and the optical axis of the phase delay optical element is a preset target angle θ0, and satisfies θ0=initial angle+first angle θ1.

9. The method for preparing a polarization-independent optical modulator based on a special optical axis design according to claim 1, characterized in that: After step S5, the following steps are also included: Step S6: attaching the transparent upper substrate to the half device, aligning and assembling, using a gap control material to control the thickness of the liquid medium layer, and sealing the edge of the device to form a polarization-independent light modulator. A polarization-independent optical modulator based on a special optical axis design, characterized in that: The method for preparing a polarization-independent optical modulator based on a special optical axis design according to any one of claims 1 to 9 is adopted, and the polarization-independent optical modulator comprises: A reflective electrode substrate is prepared by treating the surface of a low-resistance electrode substrate having a reflective function; An alignment layer is coated on the reflective electrode substrate and patterned using a micro-nano structure template method; A phase delay optical element is stacked on the alignment layer, and the optical axis direction thereof forms a preset first angle with the molecular alignment direction of the alignment layer; The liquid medium layer is formed by filling a liquid molecular material having an orientation characteristic on the phase delay optical element; The packaging layer is arranged on the peripheral side of the device and is used to seal the polarization-independent optical modulation device.

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