A production method for a refractive-diffractive hybrid two-dimensional optical waveguide

Abstract

This application relates to a method for producing a refractive and diffractive hybrid two-dimensional optical waveguide, belonging to the technical field of optical waveguide design, and includes the following steps: S1, setting the beam transmission path and determining the coupling-in region, transition region, and coupling-out region on the waveguide plate; S2, forming an array coupling-in grating and an array coupling-out grating in the coupling-in and coupling-out regions defined on the waveguide plate using an array waveguide grating process; S3, determining the grating period, transparent portion width, grating width, resolution, and dispersion rate of the transition region based on a preset calculation rule; S4, using the calculation data from S3, forming a diffraction transition grating in the transition region defined on the waveguide plate using a surface relief process. The hybrid refractive and diffractive waveguide results in a lower overall cost, better color, higher brightness and luminous efficiency, simpler process, higher mass production capability, less susceptibility to rainbow patterns, and no light leakage from the back side. It also requires low equipment costs and has a coupling efficiency close to 100%, leading to better performance.

Description

Technical Field

[0001] This application relates to the field of optical waveguide design technology, and in particular to a method for producing a refractive and diffractive hybrid two-dimensional optical waveguide. Background Technology

[0002] Augmented Reality (AR) and Virtual Reality (VR) are technologies that have garnered significant attention in recent years. Both of their near-eye display systems use pixels on a display to form a distant virtual image through a series of optical imaging elements and project it into the viewer's eye. The difference lies in the fact that AR glasses require perspective, needing to see both the real external world and virtual information. Therefore, the imaging system cannot obstruct the viewer's line of sight. This necessitates the addition of one or more optical combiners to integrate virtual information and the real scene in a "layered" manner, allowing them to complement and "enhance" each other.

[0003] Optical waveguide technology is a unique optical component developed to meet the needs of AR glasses. In AR glasses, "total internal reflection" is key to ensure that light travels without loss or leakage during transmission. This means that light travels through the waveguide like a snake, reflecting back and forth without being transmitted. This characteristic of optical waveguides has great advantages for optimizing head-mounted device design and enhancing aesthetics. There are two main types of commonly used two-dimensional pupil-expanding optical waveguide solutions: arrayed optical waveguides and diffractive optical waveguides.

[0004] However, research has revealed the following technical problems: the array waveguide process is complex, especially the process of the transition part, which makes it difficult to mass-produce and the cost is extremely high; among the two mainstream schemes of diffractive waveguides, the surface relief method has defects such as extremely high cost of the master plate and limited lifespan, back light leakage, extremely low light efficiency, rainbow patterns and uneven color caused by external light entering; the volume holographic method has defects such as slightly lower light efficiency than the array, rainbow patterns caused by external light entering, uneven color, and less back light leakage.

[0005] In response to the aforementioned technologies, a solution is proposed. Summary of the Invention

[0006] The purpose of this application is to provide a method for producing a refractive and diffractive hybrid two-dimensional optical waveguide to solve the technical problems of low coupling-in and coupling-out efficiency, back-side light leakage, easy generation of rainbow patterns, complex process and difficult manufacturing in the prior art.

[0007] This application provides a method for manufacturing a hybrid refractive and diffractive two-dimensional optical waveguide, which adopts the following technical solution:

[0008] A method for manufacturing a refractive and diffractive hybrid two-dimensional optical waveguide includes the following steps:

[0009] S1. Set the beam transmission path and determine the coupling-in region, turning region and coupling-out region on the waveguide plate;

[0010] S2. An arrayed coupling grating and an arrayed coupling grating are formed in the coupling-in region and coupling-out region defined by the arrayed waveguide grating process in the waveguide plate.

[0011] S3. Based on the preset calculation rules of the transition region, determine the grating period, the width of the light-transmitting part, the grating width, the resolution, and the dispersion rate of the transition region;

[0012] S4. Using the calculation data from S3, a diffraction deflection grating is formed in the deflection zone defined by the waveguide plate through a surface relief process.

[0013] By employing the above technical solution, the propagation path of the light beam is precisely planned to ensure that the light can efficiently enter from the coupling region, pass through the transition region, and exit from the coupling region. An arrayed coupling grating and an arrayed coupling-out grating are formed in the coupling regions defined by the waveguide plate using an arrayed waveguide grating process. This step utilizes advanced photolithography technology, using high-precision photolithography equipment to etch tiny grating structures onto the waveguide plate. These grating structures can effectively control the propagation direction and distribution of the light beam, achieving efficient optical coupling. Based on the preset calculation rules of the transition region, the grating period, the width of the transparent portion, the grating width, the resolution, and the dispersion rate of the transition region are determined. This step requires comprehensive consideration of factors such as the wavelength and refractive index of the light, and through precise calculation and simulation, the optimal grating parameters are determined. These parameters directly affect the performance of the transition region and the overall system's optical efficiency. Using the calculated data, a diffraction transition grating is formed in the transition region defined by the waveguide plate using a surface relief process. Surface relief is a high-precision micro-nano fabrication technology that achieves diffraction control of light by etching tiny concave and convex structures on the material surface. This step requires strict control of process parameters to ensure the accuracy and consistency of the diffraction transition grating. In general, this process achieves a high-efficiency, low-cost optical solution through precise beam transmission path planning, high-precision grating fabrication, and fine diffraction transition grating processing. It not only improves light utilization but also optimizes color performance and brightness efficiency, providing core optical components for augmented reality devices and other applications.

[0014] Preferably, in step S1, the waveguide plate's parameters are determined through calculation, and the calculation formula is as follows:

[0015]

[0016] Where W represents the width of the waveguide plate; λ represents the wavelength that can pass through; n eff α represents the effective refractive index; h represents the thickness of the waveguide plate; n represents the refractive index of the waveguide plate; α represents the incident angle; β represents the diffraction angle. The coupling zone, transition zone, and coupling out zone are divided based on the calculation results of the above formula.

[0017] By adopting the above scheme, in step S1, the width of the waveguide plate needs to be calculated first. According to the formula, the width of the waveguide plate is related to the wavelength that can pass through, the effective refractive index, and the thickness of the waveguide plate. This formula is derived based on the wave theory of light; by considering the propagation path of light in the waveguide and the change in refractive index, a suitable waveguide plate width can be obtained. Next, we need to calculate the positions of the coupling-in region, the turning region, and the coupling-out region. According to the formula, the distance between the coupling-in region, the turning region, and the coupling-out region is related to the wavelength that can pass through, the effective refractive index, and the diffraction angle. This formula is derived based on the diffraction theory of light; by considering the propagation path of light in the waveguide and the change in diffraction angle, a suitable position of the coupling-in region, the turning region, and the coupling-out region can be obtained. Through the above calculation formula and process flow, the position and shape of the coupling-in region, the turning region, and the coupling-out region can be accurately determined, thereby achieving efficient beam transmission and control. This process method has the advantages of high efficiency and low cost, and is suitable for various optical applications.

[0018] Preferably, in step S2, the process flow of the arrayed waveguide grating is as follows:

[0019] A1. Spin-coat a layer of photoresist onto the substrate, and expose the photoresist to ultraviolet light through a mask to form the desired pattern;

[0020] A2. Use a developer to treat the exposed photoresist, and use reactive ion beam etching technology to transfer the pattern onto the substrate material;

[0021] A3. Perform necessary coating treatment on the etched substrate, and then perform polishing treatment;

[0022] A4. Detect and test the completed array-coupled grating and array-coupled-out grating.

[0023] By adopting the above scheme, A1 is the foundation of the entire process flow. By precisely controlling the exposure time and light intensity, clear patterns can be formed on the photoresist. These patterns will serve as templates for subsequent etching processes. A2 uses a developer to treat the exposed photoresist, and then uses reactive ion beam etching technology to transfer the patterns onto the substrate material. The developer removes the unexposed photoresist, leaving the exposed patterns. Then, reactive ion beam etching technology is used to transfer these patterns onto the substrate material. This is a high-precision micro-nano fabrication technology that can achieve precise etching of the substrate material. A3 involves performing necessary coating treatments on the etched substrate, followed by polishing. The purpose of the coating treatment is to improve the reflectivity and transmittance of the substrate material, thereby improving optical performance. Polishing is to remove surface irregularities and improve the surface quality of the substrate. A4 is for quality control of the entire process flow. Through various detection methods, such as microscopic observation and spectral analysis, it is ensured that each grating meets the design requirements. Simultaneously, a series of performance tests are required, such as coupling efficiency and transmission loss, to ensure that the grating's performance meets the needs of practical applications. In general, the above process can produce high-quality array-coupled gratings and array-coupled-out gratings. This process has the advantages of high efficiency and low cost.

[0024] Preferably, in step S3, the formula for calculating the grating period of the transition region is as follows:

[0025]

[0026] Where n represents the diffraction order; λ represents the wavelength of the incident light; α represents the incident angle; β represents the diffraction angle; d represents the grating period, and the grating period is the spacing of the grating fringes. The spacing of the grating fringes of the diffraction grating is calculated using the above formula.

[0027] By adopting the above solution,

[0028] Preferably, in step S3, the formula for calculating the width of the light-transmitting portion of the transition zone is as follows:

[0029] a = FF × d;

[0030] Wherein, FF represents the duty cycle; d represents the grating period; and a represents the width of the transmitted portion. By determining FF and d, the width of the transmitted portion of the diffraction grating can be calculated.

[0031] By adopting the above scheme, in step S3, we need to calculate the grating period in the transition region, that is, the spacing of the grating fringes. According to the formula, the grating period is related to the diffraction order, the wavelength of the incident light, and the incident and diffraction angles. The derivation of this formula is based on the theory of light diffraction. By considering the propagation path of light in the grating and the changes in the diffraction angle, a suitable grating period can be obtained. Through the above calculation formula and process flow, the grating fringe spacing in the transition region can be accurately determined. This process method has the advantages of high efficiency and low cost, and is suitable for various optical applications.

[0032] Preferably, in step S3, the formula for calculating the resolution R of the transition region is:

[0033]

[0034] in, This represents the wavelength difference between two adjacent spectral lines; n represents the spectral order; N represents the total number of lines on the diffraction grating. The wavelength is represented, and the minimum resolvable object size of the diffraction transition grating is determined by calculating the resolution R.

[0035] By adopting the above scheme, in step S3, we need to calculate the resolution R of the transition region, that is, the minimum resolvable object size of the diffraction transition grating. According to the formula, we can conclude that the resolution is related to the wavelength difference between two adjacent spectral lines, the spectral order, and the total number of lines in the diffraction transition grating. The derivation of this formula is based on the principles of spectroscopy. By considering the propagation and diffraction phenomena of light in the grating, a suitable resolution can be obtained. Through the above calculation formula and process flow, the minimum resolvable object size of the transition region grating can be accurately determined.

[0036] Preferably, in step S3, the formula for calculating the dispersion rate of the transition region is as follows:

[0037]

[0038] Among them, D i Let dl represent the dispersion rate; dl represent the distance between adjacent spectral lines; and dλ represent the wavelength difference between adjacent spectral lines. The grating constant D is derived from the calculation of the dispersion rate, thereby allowing the calculation of the width of the diffraction grating. The formula for calculating the width of the diffraction grating is as follows:

[0039] W1 = ND;

[0040] Where W1 represents the width of the diffraction transition grating; N represents the total number of lines on the diffraction transition grating; and D represents the length of the minimum repeating period on the diffraction transition grating. The linear density of the diffraction transition grating is obtained through the above calculations. Thus, the diffraction efficiency of the diffraction transition grating is obtained.

[0041] By adopting the above scheme, in step S3, we need to calculate the dispersion rate of the transition region and the width of the diffraction transition grating. First, according to the formula, we can see that the dispersion rate is related to the distance between adjacent spectral lines and the wavelength difference between adjacent spectral lines. The derivation of this formula is based on the principles of spectroscopy. By considering the propagation and diffraction of light in the grating, a suitable dispersion rate can be obtained. When calculating, we first need to determine the distance dl between adjacent spectral lines, which is one of the basic properties of the spectrum. Then, we need to know the wavelength difference dλ between adjacent spectral lines, which is also one of the basic properties of the spectrum. Next, we substitute these parameters into the formula to calculate the dispersion rate.

[0042] Preferably, in step S4, the process flow of the surface relief process of the diffraction transition grating is as follows:

[0043] B1. Motherboard preparation: A positive photoresist layer is uniformly coated at the turning area of ​​the waveguide board, and the thickness of the positive photoresist layer is controlled to be 180mm.

[0044] B2. Exposure and Development: The waveguide plate with a uniform photoresist mask is subjected to contact exposure and development to obtain a waveguide plate with a photoresist mask in the transition area. Then, the transition area is subjected to interference exposure and development to obtain a waveguide plate with a grating mask in the transition area.

[0045] B3. Etching process: Dry etching is performed using trifluoromethane gas to form the diffraction transition grating in the transition region.

[0046] By adopting the above scheme, in the motherboard preparation stage, we uniformly coat the transition area of ​​the waveguide plate with a positive photoresist layer. Positive photoresist is a material that undergoes a chemical reaction under ultraviolet light irradiation, and its thickness needs to be precisely controlled at 180 nanometers. The purpose of this step is to provide a uniform mask layer for the subsequent photolithography process. Next, exposure and development are performed. We perform contact exposure and development on the waveguide plate with the uniform photoresist mask to obtain a waveguide plate with a photoresist mask in the transition area. Then, we perform interference exposure and development on the transition area. This step is crucial because it forms a waveguide plate with a grating mask in the transition area. Interference exposure is a technique that uses the interference phenomenon of two or more coherent beams of light to generate fine patterns, making it very suitable for manufacturing high-precision grating structures. Finally, etching is performed. We use trifluoromethane gas for dry etching, a commonly used micro / nano fabrication technique that can form the desired patterns on the substrate material. At this stage, we form a diffraction transition grating in the transition region. In summary, through the above process, we can accurately fabricate a diffraction transition grating on the waveguide plate. This process has the advantages of high efficiency and low cost, and is suitable for various optical applications.

[0047] In summary, this application includes at least one of the following beneficial technical effects:

[0048] 1. A geometric method is used for light coupling in and out, resulting in a coupling efficiency close to 100%. This means that almost all light entering the system can be effectively utilized, greatly improving the system's luminous efficiency;

[0049] 2. Using diffraction to achieve the turning point is a relatively simple process because the processing of diffraction elements does not require complex lens grinding and polishing processes, resulting in relatively low overall costs.

[0050] 3. Leveraging the advantages of arrays, excellent color performance can be achieved. By precisely controlling the parameters of the diffraction elements, precise control of light of different wavelengths can be achieved, thus presenting a rich variety of colors;

[0051] 4. It has high overall brightness and light efficiency, providing higher brightness output while being less prone to rainbow patterns;

[0052] 5. Lower equipment requirements. Due to its simple production process and suitability for large-scale mass production, it does not require expensive production equipment or complex production line layouts. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the overall three-dimensional structure of a refractive and diffractive hybrid two-dimensional optical waveguide according to this application;

[0054] Figure 2This is a front view schematic diagram of a refractive and diffractive hybrid two-dimensional optical waveguide according to this application;

[0055] Figure 3 This is a flowchart of a method for producing a refractive and diffractive hybrid two-dimensional optical waveguide according to this application;

[0056] Figure 4 This is a flowchart of the waveguide plate processing using the array waveguide grating process and surface relief process described in this application.

[0057] Explanation of reference numerals in the attached figures: 1. Waveguide plate; 2. Arrayed coupling grating; 3. Diffraction deflection grating; 4. Arrayed coupling out grating. Detailed Implementation

[0058] The following is in conjunction with the appendix Figure 1 - Appendix Figure 4 This application will be described in further detail below.

[0059] This application discloses a method for producing a refractive and diffractive hybrid two-dimensional optical waveguide.

[0060] Reference Figure 1 , Figure 2 and Figure 3 A method for producing a refractive and diffractive hybrid two-dimensional optical waveguide includes the following steps:

[0061] S1. Set the beam transmission path and determine the coupling-in region, turning region and coupling-out region on waveguide plate 1;

[0062] S2. An arrayed coupling grating 2 and an arrayed coupling grating 4 are formed in the coupling-in region and coupling-out region defined by the arrayed waveguide grating process in the waveguide plate 1.

[0063] S3. Based on the preset calculation rules of the transition zone, determine the grating period, the width of the light-transmitting part, the grating width, the resolution, and the dispersion rate of the transition zone;

[0064] S4. Using the calculation data from S3, a diffraction transition grating 3 is formed in the transition zone defined by the waveguide plate 1 through a surface relief process.

[0065] Specifically, first, we need to determine the propagation path of the light beam in waveguide 1. This includes defining the coupling-in region, the turning region, and the coupling-out region. The coupling-in region is where the light beam enters waveguide 1, the turning region is the area where the light beam changes direction, and the coupling-out region is where the light beam leaves waveguide 1. The division of these three regions needs to be determined based on the actual application requirements and the characteristics of the light beam. Next, we use an arrayed waveguide grating process to form an arrayed coupling-in grating 2 and an arrayed coupling-out grating 4 in the coupling-in and coupling-out regions of waveguide 1. The function of these gratings is to focus and guide the light beam to a specific direction. The arrayed coupling-in grating 2 is located in the coupling-in region and is used to couple an external light source into waveguide 1; the arrayed coupling-out grating 4 is located in the coupling-out region and is used to extract the light beam from waveguide 1. Then, based on the preset calculation rules for the turning region, we need to determine parameters such as the grating period, the width of the transparent portion, the grating width, the resolution, and the dispersion rate of the turning region. The selection of these parameters will affect the behavior of the beam in the transition region, so precise calculations are required based on specific application requirements. Finally, using the data calculated in step S3, we form a diffraction transition grating 3 in the transition region defined by the waveguide plate 1 through a surface relief process. This grating can change the propagation direction of the beam, thereby achieving beam turning or dispersion.

[0066] Reference Figure 3 In step S1, the parameters of waveguide plate 1 are determined through calculation, and the calculation formula is as follows:

[0067]

[0068] Where W represents the width of waveguide 1; λ represents the wavelength that can pass through; n eff α represents the effective refractive index; h represents the thickness of waveguide plate 1; n represents the refractive index of waveguide plate 1; α represents the incident angle; β represents the diffraction angle. The coupling zone, transition zone and coupling out zone are divided by the calculation results of the above formula.

[0069] Specifically, there are certain mathematical relationships between these parameters. Through these relationships, we can calculate the incident angle α and the diffraction angle β. After determining these parameters, we can divide the beam into the coupling zone, the turning zone, and the coupling zone based on the calculation results. The coupling zone is the position where the beam enters the waveguide plate 1, and its position and size need to be determined according to the incident angle α. The turning zone is the area where the beam changes direction, and its position and size need to be determined according to the diffraction angle β. The coupling zone is the position where the beam leaves the waveguide plate 1, and its position and size also need to be determined according to the diffraction angle β. When dividing the regions, we need to ensure that each region can effectively guide the beam and avoid beam loss during transmission.

[0070] Reference Figure 3 and Figure 4In step S2, the process flow of the arrayed waveguide grating is as follows:

[0071] A1. Spin-coat a layer of photoresist onto the substrate, and expose the photoresist to ultraviolet light through a mask to form the desired pattern;

[0072] A2. Use a developer to treat the exposed photoresist, and use reactive ion beam etching technology to transfer the pattern onto the substrate material;

[0073] A3. Perform necessary coating treatment on the etched substrate, and then perform polishing treatment;

[0074] A4. Detect and test the completed array coupling grating 2 and array coupling output grating 4.

[0075] Specifically, firstly, a layer of photoresist, a photosensitive material that undergoes a chemical change under ultraviolet light, is uniformly spin-coated onto the substrate. Then, a photomask is placed on top of the photoresist; the pattern on the photomask determines the final shape and layout of the grating. Through ultraviolet exposure, the photoresist polymerizes in the unmasked areas, forming a pattern corresponding to the photomask pattern. After exposure, the photoresist needs to be treated with a developer to remove the unexposed areas, leaving the desired pattern. Next, reactive ion beam etching is used to transfer the pattern onto the substrate material. This step involves bombarding the substrate with a high-energy ion beam, etching away the areas not protected by the photoresist to form a precise grating structure on the substrate. After etching, a coating process may be required on the substrate to enhance the grating's performance or prepare it for subsequent processes. The coating can be a metal, dielectric, or other functional material. Afterward, polishing is performed to ensure the flatness and smoothness of the grating surface. Finally, the completed array-coupled grating 2 and array-coupled grating 4 undergo comprehensive inspection and testing. This includes checking whether the size, shape, position, and optical performance of the grating meet the design requirements.

[0076] Reference Figure 3 In step S3, the formula for calculating the grating period in the transition region is as follows:

[0077]

[0078] Where n represents the diffraction order; λ represents the wavelength of the incident light; α represents the incident angle; β represents the diffraction angle; and d represents the grating period, which is the spacing between the grating fringes. The spacing between the grating fringes of the diffraction transition grating 3 is calculated using the above formula.

[0079] Specifically, firstly, the parameters mentioned above are determined based on the system design requirements and actual application environment. These collected parameters are then substituted into the formula to calculate the grating period d. This calculation process requires ensuring that all parameters use consistent units; typically, wavelength is measured in nanometers, and angles in radians or degrees. The calculated grating period d will serve as the basis for designing the transition zone grating. Before finalizing the grating period, the designed grating can be simulated using optical simulation software to verify whether its diffraction effect under different incident conditions meets expectations. This helps to identify potential problems and make adjustments in advance. Ansys Zemax OpticStudio can be used for this simulation. All calculation results and design decisions should be recorded in detail, including the specific value of the grating period, the formula used, and the assumptions, for reference in subsequent production, testing, and quality control stages.

[0080] Reference Figure 3 In step S3, the formula for calculating the width of the light-transmitting portion of the transition zone is as follows:

[0081] a = FF × d;

[0082] Where FF represents the duty cycle; d represents the grating period; and a represents the width of the transmitted portion. By determining FF and d, the width of the transmitted portion of the diffraction transition grating 3 can be calculated.

[0083] Specifically, first, we need to know the overall period of the grating, which determines the spacing of the grating lines. Then, based on the duty cycle, we can determine what percentage of the period is transparent, allowing us to calculate the actual width of the transparent portion. In terms of manufacturing, once we determine the width of the transparent portion, we can use a surface relief process to precisely fabricate this type of diffraction deflection grating 3 on the waveguide plate 1. In this way, we can ensure that the light beam diffracts in the deflection region as expected, thereby achieving effective beam redirection or dispersion.

[0084] Reference Figure 3 In step S3, the formula for calculating the resolution R of the transition region is:

[0085]

[0086] in, This represents the wavelength difference between two adjacent spectral lines; n represents the spectral order; N represents the total number of lines in the diffraction grating 3. The wavelength is represented, and the minimum resolvable object size of the diffraction transition grating 3 is determined by calculating the resolution R.

[0087] Specifically, this calculation is based on the principles of optical diffraction and interference. When a beam of light passes through the diffraction transition grating 3, light of different wavelengths undergoes diffraction to varying degrees, thus forming a spectrum. The resolution R represents the smallest wavelength difference that the spectrometer can distinguish, i.e., the wavelength difference between two adjacent spectral lines. By determining the duty cycle FF and the grating period d, we can calculate the width a of the transparent portion of the diffraction transition grating 3. This helps to further optimize the design of the diffraction transition grating 3 and improve its resolution. In terms of process implementation, once the resolution R is determined, we can design and manufacture the diffraction transition grating 3 based on this parameter.

[0088] Reference Figure 3 In step S3, the formula for calculating the dispersion rate in the transition region is as follows:

[0089]

[0090] Among them, D i d represents the dispersion rate; dl represents the distance between adjacent spectral lines; dλ represents the wavelength difference between adjacent spectral lines. The grating constant D is derived from the calculation of the dispersion rate, and thus the width of the diffraction transition grating 3 can be calculated. The formula for calculating the width of the diffraction transition grating 3 is as follows:

[0091] W1 = ND;

[0092] Where W1 represents the width of the diffraction transition grating 3; N represents the total number of lines on the diffraction transition grating 3; and D represents the length of the minimum repeating period on the diffraction transition grating 3. The linear density of the diffraction transition grating 3 is obtained through the above calculations. Thus, the diffraction efficiency of diffraction transition grating 3 is obtained.

[0093] Specifically, the first step is to calculate the dispersion rate D in the transition region. i Dispersion D iThe dispersion rate is the ratio between the distance between adjacent spectral lines and the wavelength difference between them. Through measurement and calculation, we can obtain the specific value of the dispersion rate. Next, we need to use the dispersion rate to calculate the grating constant D. The grating constant is an important parameter describing the grating structure; it represents the length of the minimum repetition period on the grating. According to the formula for calculating the dispersion rate, we can substitute the known dispersion rate into the formula to obtain the value of the grating constant D. Then, we can calculate the width of the diffraction transition grating 3 based on the grating constant D. The diffraction transition grating 3 is an important component in optical systems, and its width has a significant impact on the system's diffraction efficiency. Based on the diffraction transition grating 3... To calculate the width of the diffraction transition grating 3, we only need to know the total number of lines N and the grating constant D. Then, using the linear density of the diffraction transition grating 3 obtained from the above calculations, we can further derive its diffraction efficiency. Diffraction efficiency is an important indicator of the performance of optical elements, reflecting their ability to diffract incident light. By calculating the linear density of the diffraction transition grating 3, we can obtain its specific diffraction efficiency. In summary, by calculating the dispersion rate, grating constant, width of the diffraction transition grating 3, and diffraction efficiency, we can comprehensively understand and evaluate the performance characteristics of the diffraction transition grating 3.

[0094] Reference Figure 3 and Figure 4 In step S4, the process flow of the surface relief process of the diffraction transition grating 3 is as follows:

[0095] B1. Motherboard preparation: A positive photoresist layer is uniformly coated at the turning area of ​​waveguide 1, and the thickness of the positive photoresist layer is controlled to be 180mm.

[0096] B2. Exposure and Development: The waveguide plate 1 with a uniform photoresist mask is subjected to contact exposure and development to obtain the waveguide plate 1 with a photoresist mask in the transition area. Then, the transition area is subjected to interference exposure and development to obtain the waveguide plate 1 with a grating mask in the transition area.

[0097] B3. Etching process: Dry etching is performed using trifluoromethane gas to form a diffraction transition grating 3 in the transition region.

[0098] Specifically, the waveguide plate 1 is thoroughly cleaned using a mixed solution of acetone, sulfuric acid, and hydrogen peroxide to ensure that the surface is free of impurities. A positive photoresist layer is uniformly coated on the surface of the waveguide plate 1 with a thickness controlled at 180 mm. The target structural area is shielded using a photomask. The waveguide plate 1 with the uniform photoresist mask is subjected to contact exposure and development to obtain the waveguide plate 1 with the photoresist mask in the target structural area. Then, the waveguide plate 1 with the photoresist mask in the target structural area is subjected to interference exposure and development to obtain the waveguide plate 1 with the grating mask in the target structural area. The appropriate etching method is selected according to the material of the waveguide plate 1. It is generally made of quartz glass and is often dry etched using trifluoromethane gas. During the etching process, parameters such as etching speed, depth, and sidewall tilt angle must be strictly controlled.

[0099] The implementation principle of this application embodiment is as follows: The refractive and diffractive hybrid two-dimensional optical waveguide design combines two optical phenomena, refraction and diffraction, to achieve effective control of light waves. This design forms a specific grating structure on the waveguide plate 1, utilizing the interference and diffraction effects of light to achieve the coupling, deflection, and output of the light beam. The entire design process includes steps such as setting the beam transmission path, forming the grating, calculating the deflection region parameters, and implementing the surface relief process. This is based on the width W of the waveguide plate 1, the wavelength λ that can pass through, and the effective refractive index n. effThe waveguide thickness h, refractive index n, incident angle α, and diffraction angle β are used to determine the positions and dimensions of the coupling region, turning region, and coupling region through a series of calculation formulas. These parameters ensure that the beam propagation path within the waveguide 1 meets design requirements and reduces energy loss. Within the coupling region and coupling region, an array of gratings is formed using photolithography. This step involves processes such as substrate spin-coating of photoresist, ultraviolet exposure, development, reactive ion beam etching, coating, and polishing, ultimately yielding the desired grating structure. These gratings are used for beam coupling and output, and their precise geometric parameters... The transmission efficiency of the light beam is crucial. The grating period *d* in the transition region is determined by the diffraction order *n*, the incident wavelength *λ*, the incident angle *α*, and the diffraction angle *β*. The width *a* of the transmitted portion is determined by the duty cycle *FF* and the grating period *d*. The resolution *R* is determined by the wavelength difference between adjacent spectral lines and the total number of lines *N* in the diffraction transition grating 3. The dispersion rate *D* is determined by the distance *dl* between adjacent spectral lines and the wavelength difference. The calculation of these parameters ensures the precise design and high efficiency of the transition grating. A positive photoresist layer is uniformly coated at the transition region, and a photoresist mask is formed through contact exposure and development. Subsequently, interference exposure and development are performed to obtain the waveguide plate 1 with the grating mask. Finally, dry etching is performed using trifluoromethane gas to form the diffraction transition grating 3. Precise control of this process step is crucial for achieving high diffraction efficiency and low loss. The above design, through precise calculation and fine process control, achieves precise setting of the beam transmission path and high-precision fabrication of the grating structure. At the same time, the optimized grating parameters and process steps reduce energy loss of the beam during transmission, improving transmission efficiency.

[0100] The embodiments described herein are preferred embodiments and are not intended to limit the scope of protection of this application. Identical components are indicated by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be included within the scope of protection of this application.

Claims

1. A method for producing a hybrid refractive and diffractive two-dimensional optical waveguide, characterized in that, Includes the following steps: S1. Set the beam transmission path, and determine the coupling-in region, turning region and coupling-out region on the waveguide plate (1). The parameters of the waveguide plate (1) are determined after calculation. The calculation formula is as follows: Where W represents the width of the waveguide plate (1); λ represents the wavelength that can pass through; n eff α represents the effective refractive index; h represents the thickness of the waveguide plate (1); n represents the refractive index of the waveguide plate (1); α represents the incident angle; β represents the diffraction angle. The coupling zone, transition zone and coupling out zone are divided by the calculation results of the above formula. S2. An arrayed coupling grating (2) and an arrayed coupling grating (4) are formed in the coupling-in region and coupling-out region defined by the arrayed waveguide grating process on the waveguide plate (1). S3. Based on the preset calculation rules for the transition region, determine the grating period, the width of the light-transmitting portion, the grating width, the resolution, and the dispersion rate of the transition region. The calculation formula for the grating period of the transition region is as follows: Where n represents the diffraction order; The wavelength of the incident light is represented by α; the incident angle is represented by β; the diffraction angle is represented by β; and the grating period is the spacing of the grating fringes. The spacing of the grating fringes of the diffraction grating (3) is calculated using the above formula. S4. Using the calculation data of S3, a diffraction transition grating (3) is formed in the transition zone defined by the waveguide plate (1) through a surface relief process.

2. The method for producing a refractive and diffractive hybrid two-dimensional optical waveguide according to claim 1, characterized in that, In step S2, the process flow of the arrayed waveguide grating is as follows: A1. Spin-coat a layer of photoresist onto the substrate, and expose the photoresist to ultraviolet light through a mask to form the desired pattern; A2. Use a developer to treat the exposed photoresist, and use reactive ion beam etching technology to transfer the pattern onto the substrate material; A3. Perform necessary coating treatment on the etched substrate, and then perform polishing treatment; A4. The completed array coupling grating (2) and array coupling grating (4) are inspected and tested.

3. The method for producing a refractive-diffractive hybrid two-dimensional optical waveguide according to claim 2, characterized in that, In step S3, the formula for calculating the width of the light-transmitting portion of the transition zone is as follows: a = FF × d; Wherein, FF represents the duty cycle; d represents the grating period; and a represents the width of the light-transmitting portion. By determining FF and d, the width of the light-transmitting portion of the diffraction transition grating (3) can be calculated.

4. The method for producing a refractive and diffractive hybrid two-dimensional optical waveguide according to claim 1, characterized in that, In step S3, the formula for calculating the resolution R of the transition region is: in, The difference in wavelength between two adjacent spectral lines is represented by n; the spectral order is represented by n; and the total number of lines on the diffraction grating (3) is represented by N. The minimum resolvable object size of the diffraction transition grating (3) is determined by calculating the resolution R, which represents the wavelength.

5. The method for producing a refractive-diffractive hybrid two-dimensional optical waveguide according to claim 1, characterized in that, In step S3, the formula for calculating the dispersion rate of the transition region is as follows: Among them, D i dl represents the dispersion rate; dl represents the distance between adjacent spectral lines; dλ represents the wavelength difference between adjacent spectral lines. The grating constant D is derived from the calculation of the dispersion rate, thereby calculating the width of the diffraction transition grating (3). The formula for calculating the width of the diffraction transition grating (3) is as follows: W1 = ND; Where W1 represents the width of the diffraction transition grating (3); N represents the total number of lines on the diffraction transition grating (3); and D represents the length of the minimum repeating period on the diffraction transition grating (3). The linear density of the diffraction transition grating (3) is obtained through the above calculations. Thus, the diffraction efficiency of the diffraction transition grating (3) is obtained.

6. The method for producing a refractive-diffractive hybrid two-dimensional optical waveguide according to claim 1, characterized in that, In step S4, the process flow of the surface relief process of the diffraction deflection grating (3) is as follows: B1. Motherboard preparation: A positive photoresist layer is uniformly coated at the turning area of ​​the waveguide plate (1), and the thickness of the positive photoresist layer is controlled to be 180mm. B2. Exposure and development: The waveguide plate (1) with a uniform photoresist mask is subjected to contact exposure and development to obtain the waveguide plate (1) with a photoresist mask in the transition area. Then, the transition area is subjected to interference exposure and development to obtain the waveguide plate (1) with a grating mask in the transition area. B3. Etching process: Dry etching is performed using trifluoromethane gas to form the diffraction transition grating (3) in the transition region.

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