Production method of refraction and diffraction mixed two-dimensional optical waveguide

Abstract

The invention relates to a refraction and diffraction mixed two-dimensional optical waveguide production method, and relates to the technical field of optical waveguide design, and the method comprises the following steps: S1, setting a light beam transmission path, and determining a coupling-in region, a transition region and a coupling-out region on a waveguide plate; s2, forming an array coupling-in grating and an array coupling-out grating in the coupling-in area and the coupling-out area delimited by the waveguide plate through an array waveguide grating process; s3, based on a preset calculation rule of the transition area, determining a grating period, a light-transmitting part width, a grating width, a resolution ratio and a dispersion rate of the transition area; and S4, forming a diffraction turning grating in a turning region delimited by the waveguide plate by using calculation data in S3 through a surface relief process. Through the mixing of refraction and diffraction, the two-dimensional pupil-expanding optical waveguide is relatively low in overall cost, good in color, high in brightness and light efficiency, simple in process, high in mass production, not easy to generate rainbow lines and free of light leakage on the back surface. And the equipment demand cost is low, the coupling efficiency is close to 100%, and the use effect is better.

Description

Technical Field

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

[0002] Augmented reality (AR) and virtual reality (VR) are technology fields that have received widespread attention in recent years. Their near-eye display systems use a series of optical imaging elements to form distant virtual images from the pixels on the display and project them into the human eye. The difference is that AR glasses require perspective, and must see both the real external world and virtual information, so the imaging system cannot block the line of sight. This requires adding one or a group of optical combiners to integrate virtual information and real scenes through "stacking" to complement and "enhance" each other.

[0003] Optical waveguide technology is a relatively distinctive optical component that was created to meet the needs of AR glasses. In AR glasses, in order to ensure that light is transmitted without loss or leakage, "total reflection" is the key, that is, light moves forward in the waveguide by reflecting back and forth like a snake and does not transmit out. This characteristic of the optical waveguide has great advantages in optimizing the design of the headset and beautifying the appearance. There are two main commonly used two-dimensional pupil expansion optical waveguide solutions, namely array optical waveguide and diffraction optical waveguide.

[0004] However, the study found the following technical problems: the array optical waveguide process is complicated, especially the process of the turning part, which makes it difficult to mass produce and the cost is extremely high during the production process; of the two mainstream schemes of diffraction optical waveguides, the surface relief method has defects such as extremely high master plate cost and service life, light leakage from the back, extremely low light efficiency, rainbow patterns and uneven colors caused by the entry of external light; the volume holographic method has defects such as slightly lower light efficiency than the array, rainbow patterns caused by the entry of external light, uneven colors, and less light leakage from the back.

[0005] In view of the above-mentioned related technologies, a solution is now proposed. Summary of the invention

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

[0007] The present application provides a method for producing a refractive-diffractive hybrid two-dimensional optical waveguide, which adopts the following technical solution: A method for producing a refractive-diffractive hybrid two-dimensional optical waveguide comprises the following steps: S1. Set the beam transmission path and determine the coupling-in area, turning area and coupling-out area on the waveguide plate; S2, forming an arrayed in-coupling grating and an arrayed out-coupling grating in the in-coupling area and the out-coupling area defined by the waveguide plate through an arrayed waveguide grating process; S3, determining the grating period, light-transmitting portion width, grating width, resolution and dispersion rate of the turning zone based on the preset calculation rules of the turning zone; S4. Using the calculated data of S3, a diffraction turning grating is formed in the turning area defined by the waveguide plate through a surface relief process.

[0008] By adopting the above technical solution, the transmission path of the light beam is accurately planned to ensure that the light can efficiently enter from the coupling-in area and output from the coupling-out area after passing through the turning area. The arrayed waveguide grating process forms an array coupling-in grating and an array coupling-out grating in the coupling-in area and the coupling-out area defined by the waveguide plate. This step utilizes advanced lithography technology to carve tiny grating structures on the waveguide plate through high-precision lithography equipment. These grating structures can effectively control the propagation direction and distribution of the light beam and achieve efficient light coupling. Based on the preset calculation rules of the turning area, the grating period, the width of the light-transmitting part, the grating width, the resolution and the dispersion rate of the turning area are determined. This step requires comprehensive consideration of factors such as the wavelength and refractive index of light, and the optimal grating parameters are determined through precise calculation and simulation. These parameters will directly affect the performance of the turning area and the optical efficiency of the overall system. The calculated data is used to form a diffraction turning grating in the turning area defined by the waveguide plate through the surface relief process. The surface relief process is a high-precision micro-nano processing technology that achieves diffraction control of light by carving tiny concave and convex structures on the surface of the material. This step requires strict control of process parameters to ensure the accuracy and consistency of the diffraction turn grating. In general, this process achieves a high-efficiency, low-cost optical solution through precise beam transmission path planning, high-precision grating production and fine diffraction turn grating processing. It not only improves the utilization rate of light, but also optimizes color performance and brightness effects, providing core optical components for augmented reality devices.

[0009] Preferably, in step S1, the waveguide plate is calculated to determine parameters, and the calculation formula is as follows: Where W is the width of the waveguide; λ is the wavelength that can pass through; n eff 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-in zone, turning zone and decoupling zone are divided according to the calculation results of the above formula.

[0010] By adopting the above scheme, in step S1, the width of the waveguide plate needs to be calculated first. According to the formula, we can conclude that 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. The derivation of this formula is based on the wave theory of light. By considering the propagation path of light in the waveguide and the change of the refractive index, the appropriate width of the waveguide plate can be obtained. Next, we need to calculate the position of the coupling zone, the turning zone and the decoupling zone. According to the formula, we can conclude that the distance between the coupling zone, the turning zone and the decoupling zone is related to the wavelength that can pass through, the effective refractive index and the diffraction angle. The derivation of this formula is based on the diffraction theory of light. By considering the propagation path of light in the waveguide and the change of the diffraction angle, the appropriate position of the coupling zone, the turning zone and the decoupling zone can be obtained. Through the above calculation formula and process flow, the position and shape of the coupling zone, the turning zone and the decoupling zone can be accurately determined, thereby realizing efficient beam transmission and control. This process method has the advantages of high efficiency and low cost, and is suitable for various optical applications.

[0011] Preferably, in step S2, the process flow of the arrayed waveguide grating process is: A1. Spin-coat a layer of photoresist on the substrate, and use ultraviolet light to expose the photoresist through a mask to form a desired pattern; A2. Use a developer to process the exposed photoresist and use reactive ion beam etching technology to transfer the pattern to the substrate material; A3, performing necessary coating treatment on the etched substrate, and then performing polishing treatment; A4. Detect and test the completed array coupling-in grating and array coupling-out grating.

[0012] By adopting the above scheme, A1 is the basis 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 the subsequent etching process; A2 uses a developer to process the exposed photoresist and transfers the patterns to the substrate material using reactive ion beam etching technology. The function of the developer is to remove the unexposed part of the photoresist and leave the exposed pattern. Then, these patterns are transferred to the substrate material through reactive ion beam etching technology. This is a high-precision micro-nano processing technology that can achieve accurate etching of the substrate material; A3 is the necessary coating treatment on the etched substrate, and then polishing treatment is performed. The purpose of the coating treatment is to improve the reflectivity and transmittance of the substrate material, thereby improving the optical performance. The polishing treatment is to remove the surface unevenness and improve the surface quality of the substrate; A4 is the quality control of the entire process flow, through various detection methods, such as microscopic observation, spectral analysis, etc., to ensure that each grating meets the design requirements. At the same time, a series of performance tests are also required, such as coupling efficiency, transmission loss, etc., to ensure that the performance of the grating meets the actual application requirements. In general, through the above process flow, high-quality array coupling-in gratings and array coupling-out gratings can be produced. This process method has the advantages of high efficiency and low cost.

[0013] Preferably, in step S3, the calculation formula of the grating period of the transition zone is as follows: Wherein, 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 stripes. The grating stripe spacing of the diffraction turning grating is determined by calculating the above formula.

[0014] By adopting the above scheme, Preferably, in step S3, the calculation formula of the width of the light-transmitting portion of the turning zone is as follows: a=FF×d; Wherein, FF represents the duty cycle; d represents the grating period; a represents the width of the light-transmitting portion. By determining FF and d, the width of the light-transmitting portion of the diffraction turning grating can be calculated.

[0015] By adopting the above scheme, in step S3, we need to calculate the grating period of the turning zone, that is, the spacing of the grating stripes. According to the formula, we can deduce that the grating period is related to the diffraction order, the wavelength of the incident light, and the incident angle and diffraction angle. The derivation of this formula is based on the diffraction theory of light. By considering the propagation path of light in the grating and the change of the diffraction angle, the appropriate grating period can be obtained. Through the above calculation formula and process flow, the grating stripe spacing of the turning zone grating can be accurately determined. This process method has the advantages of high efficiency and low cost, and is suitable for various optical applications.

[0016] Preferably, in step S3, the calculation formula of the resolution R of the turning zone is: in, represents the difference between the wavelengths of two adjacent spectral lines; n represents the spectral order; N represents the total number of lines of the diffraction turning grating; Represents the wavelength, and the minimum resolution object size of the diffraction turning grating is determined by calculating the resolution R.

[0017] By adopting the above scheme, in step S3, we need to calculate the resolution R of the turning zone, that is, the minimum resolution object size of the diffraction turning grating. According to the formula, we can conclude that the resolution is related to the difference in wavelengths between two adjacent spectral lines, the spectral order, and the total number of lines of the diffraction turning grating. The derivation of this formula is based on the principle of spectroscopy. By considering the propagation and diffraction phenomenon of light in the grating, a suitable resolution can be obtained. Through the above calculation formula and process flow, the minimum resolution object size of the turning zone grating can be accurately determined.

[0018] Preferably, in step S3, the calculation formula of the dispersion rate in the turning zone is as follows: Among them, D i represents the dispersion rate; dl represents the distance between adjacent spectral lines; dλ represents the difference in wavelength between adjacent spectral lines. The grating constant D is inferred from the calculation of the dispersion rate, thereby calculating the width of the diffraction turning grating. The calculation formula for the width of the diffraction turning grating is as follows: W1=ND; Wherein, W1 represents the width of the diffraction turning grating; N represents the total number of lines of the diffraction turning grating; D represents the length of the minimum repetition period on the diffraction turning grating. The line density of the diffraction turning grating is obtained by the above calculation: Thereby, the diffraction efficiency of the diffraction turn grating is obtained.

[0019] By adopting the above scheme, in step S3, we need to calculate the dispersion rate of the turning zone and the width of the diffraction turning grating. First, according to the formula, we can get that the dispersion rate is related to the distance between adjacent spectral lines and the difference in wavelengths between adjacent spectral lines. The derivation of this formula is based on the principle of spectroscopy. By considering the propagation and diffraction phenomena of light in the grating, a suitable dispersion rate can be obtained. When calculating, first, it is necessary to determine the distance dl between adjacent spectral lines, which is one of the basic properties of the spectrum. Then, it is necessary to know the difference in wavelengths dλ between adjacent spectral lines, which is also one of the basic properties of the spectrum. Next, these parameters are substituted into the formula for calculation to obtain the dispersion rate.

[0020] Preferably, in step S4, the process flow of the surface relief process of the diffraction turning grating is: B1. Motherboard preparation: a positive photoresist layer is uniformly coated on the turning area of ​​the waveguide plate, and the thickness of the positive photoresist layer is controlled to be 180 mm; B2, exposure and development: performing contact exposure and development processing on the waveguide plate with a uniform photoresist mask to obtain a waveguide plate with a photoresist mask in the turning area, and then performing interference exposure and development on the turning area to obtain a waveguide plate with a grating mask in the turning area; B3. Etching process: using trifluoromethane gas to perform dry etching to form the diffraction turning grating in the turning area.

[0021] By adopting the above scheme, during the motherboard preparation stage, we evenly coat the turning area of ​​the waveguide plate with a positive photoresist layer. Positive photoresist is a material that undergoes a chemical reaction under ultraviolet light, and its thickness needs to be precisely controlled to be 180 nanometers. The purpose of this step is to provide a uniform mask layer for the subsequent photolithography process, and then, exposure and development are performed. We perform contact exposure and development on the waveguide plate with a uniform photoresist mask to obtain a waveguide plate with a photoresist mask in the turning area. Then, we perform interference exposure and development on the turning area, which is a key step because it will form a waveguide plate with a grating mask in the turning area. Interference exposure is a technology that uses the interference phenomenon of two or more coherent light beams to produce fine patterns, which is very suitable for manufacturing high-precision grating structures. Finally, etching is performed. We use trifluoromethane gas for dry etching, which is a commonly used micro-nano processing technology that can form the desired pattern on the substrate material. At this stage, we have formed a diffraction turn grating in the turning area. In general, through the above process, we can accurately make a diffraction turn grating on the waveguide plate. This process method has the advantages of high efficiency and low cost, and is suitable for various optical applications.

[0022] In summary, the present application includes at least one of the following beneficial technical effects: 1. The light is coupled in and out in a geometric manner, which makes the coupling efficiency close to 100%. This means that almost all the light entering the system can be effectively utilized, greatly improving the light efficiency of the system; 2. The diffraction method is used for turning. This process is relatively simple because the processing of diffraction elements does not require complicated lens grinding and polishing processes, and the overall cost is relatively low; 3. Taking advantage of the array, excellent color performance can be achieved. By precisely controlling the parameters of the diffraction element, precise control of light of different wavelengths can be achieved, thus presenting rich colors; 4. The overall brightness and light efficiency are high, which can provide higher brightness output and is not easy to produce rainbow patterns; 5. The equipment requirement cost is low. Since its production process is simple and suitable for large-scale mass production, it does not require expensive production equipment and complex production line layout. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the overall three-dimensional structure of a refractive-diffractive hybrid two-dimensional optical waveguide of the present application; Figure 2 It is a schematic diagram of the front view structure of a refractive-diffractive hybrid two-dimensional optical waveguide of the present application; Figure 3 It is a flow chart of a method for producing a refractive-diffractive hybrid two-dimensional optical waveguide of the present application; Figure 4 It is a flow chart of processing a waveguide plate using an array waveguide grating process and a surface relief process in the present application.

[0024] Explanation of the reference numerals: 1. waveguide plate; 2. array coupling-in grating; 3. diffraction turning grating; 4. array coupling-out grating. DETAILED DESCRIPTION

[0025] The following is combined with Figure 1 - Attachment Figure 4 , further details of this application are given.

[0026] The embodiment of the present application discloses a method for producing a refractive-diffractive hybrid two-dimensional optical waveguide.

[0027] Reference Figure 1 , Figure 2 and Figure 3 , a method for producing a refractive-diffractive hybrid two-dimensional optical waveguide, comprising the following steps: S1, setting the beam transmission path, determining the coupling-in area, the turning area and the coupling-out area on the waveguide plate 1; S2, forming an arrayed in-coupling grating 2 and an arrayed out-coupling grating 4 in the in-coupling area and the out-coupling area defined by the waveguide plate 1 through an arrayed waveguide grating process; S3, based on the preset calculation rules of the turning zone, determining the grating period, the width of the light-transmitting portion, the grating width, the resolution and the dispersion rate of the turning zone; S4. Using the calculated data of S3, a diffraction turning grating 3 is formed in the turning area defined by the waveguide plate 1 through a surface relief process.

[0028] Specifically, first, we need to determine the transmission path of the light beam in the waveguide plate 1. This includes the division of the coupling zone, the turning zone and the decoupling zone. The coupling zone is the position where the light beam enters the waveguide plate 1, the turning zone is the area where the light beam changes direction, and the decoupling zone is the position where the light beam leaves the waveguide plate 1. The division of these three areas needs to be determined according to the actual application requirements and the characteristics of the light beam. Next, we use the array waveguide grating process to form an array coupling grating 2 and an array decoupling grating 4 in the coupling zone and decoupling zone of the waveguide plate 1. The function of these gratings is to focus and guide the light beam to a specific direction. The array coupling grating 2 is located in the coupling zone and is used to couple the external light source into the waveguide plate 1; the array decoupling grating 4 is located in the decoupling zone and is used to export the light beam from the waveguide plate 1. Then, we need to determine the parameters such as the grating period, the width of the light-transmitting part, the grating width, the resolution and the dispersion rate of the decoupling zone based on the preset calculation rules of the decoupling zone. The selection of these parameters will affect the behavior of the light beam in the turning zone, so accurate calculations are required based on specific application requirements. Finally, we use the data calculated in step S3 to form a diffraction turning grating 3 in the turning zone defined by the waveguide plate 1 through a surface relief process. This grating can change the propagation direction of the light beam, thereby achieving the steering or dispersion of the light beam.

[0029] Reference Figure 3 In step S1, the waveguide plate 1 is calculated to determine the parameters, and 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 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, and the coupling-in area, turning area and decoupling area are divided according to the calculation results of the above formula.

[0030] Specifically, there is a certain mathematical relationship between these parameters, through which we can calculate the incident angle α and the diffraction angle β. After determining these parameters, we can divide the coupling zone, turning zone and decoupling zone according to the calculation results. The coupling zone is the position where the light 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 light beam changes direction, and its position and size need to be determined according to the diffraction angle β; the decoupling zone is the position where the light 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 area, we need to ensure that each area can effectively guide the light beam and avoid the loss of the light beam during transmission.

[0031] Reference Figure 3 and Figure 4 In step S2, the process flow of the arrayed waveguide grating process is: A1. Spin-coat a layer of photoresist on the substrate, and use ultraviolet light to expose the photoresist through a mask to form a desired pattern; A2. Use a developer to process the exposed photoresist and use reactive ion beam etching technology to transfer the pattern to the substrate material; A3. Perform necessary coating treatment on the etched substrate, and then perform polishing treatment; A4. Detect and test the completed array coupling-in grating 2 and array coupling-out grating 4.

[0032] Specifically, first, a layer of photoresist is evenly spin-coated on the substrate. This is a photosensitive material that can undergo chemical changes under ultraviolet irradiation. Then, a mask is placed on top of the photoresist. The pattern on the mask determines the shape and layout of the final grating. Through ultraviolet exposure, the photoresist undergoes polymerization reaction in the unshielded part of the mask to form a pattern corresponding to the mask pattern. The exposed photoresist needs to be treated with a developer to remove the photoresist in the unexposed part and leave the required pattern. Next, the pattern is transferred to the substrate material using reactive ion beam etching technology. This step involves bombarding the substrate with a high-energy ion beam. The part not protected by the photoresist will be etched away, thereby forming a precise grating structure on the substrate. After etching, it may be necessary to coat the substrate to enhance the performance of the grating or prepare for subsequent processes. The coating can be metal, dielectric or other functional materials. After that, polishing is performed to ensure the flatness and finish of the grating surface. Finally, the completed array coupling grating 2 and array coupling grating 4 are fully inspected and tested. This includes checking whether the size, shape, position and optical performance of the grating meet the design requirements.

[0033] Reference Figure 3 , in step S3, the calculation formula of the grating period of the turning area is as follows: Wherein, 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 stripes. The grating stripe spacing of the diffraction turning grating 3 is determined by calculation using the above formula.

[0034] Specifically, first, determine the above parameters according to the design requirements of the system and the actual application environment, substitute the above collected parameters into the formula, and calculate the grating period d. This calculation process needs to ensure that the units of all parameters are consistent. Usually the wavelength is in nanometers and the angle is in radians or degrees. The calculated grating period d will serve as the basis for designing the turning zone grating. Before the grating period is finally determined, the designed grating can be simulated by optical simulation software to verify whether its diffraction effect under different incident conditions meets expectations. This helps to discover potential problems in advance and make adjustments. The optical simulation software used can be Ansys Zemax OpticStudio. All calculation results and design decisions are recorded in detail, including the specific value of the grating period, the formula and assumptions based on it, etc., for reference in subsequent production, testing and quality control links.

[0035] Reference Figure 3 In step S3, the calculation formula of the width of the light-transmitting portion of the turning zone is as follows: a=FF×d; Among them, FF represents the duty cycle; d represents the grating period; a represents the width of the light-transmitting portion. By determining FF and d, the width of the light-transmitting portion of the diffraction turning grating 3 can be calculated.

[0036] 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 how much of the period is transparent, so that we can calculate the actual width of the transparent part. In terms of process implementation, once we determine the width of the transparent part, we can use the surface relief process to accurately manufacture the diffraction turning grating 3 of this structure on the waveguide plate 1. In terms of process implementation, once we determine the width of the transparent part, we can use the surface relief process to accurately manufacture the diffraction turning grating 3 of this structure on the waveguide plate 1. In this way, we can ensure that the light beam can be diffracted in the turning area in the expected manner, thereby achieving effective steering or dispersion of the light beam.

[0037] Reference Figure 3 In step S3, the calculation formula of the resolution R of the turning area is: in, represents the difference between the wavelengths of two adjacent spectral lines; n represents the spectral order; N represents the total number of lines of the diffraction turning grating 3; Represents the wavelength, and the minimum resolution object size of the diffraction turning grating 3 is determined by calculating the resolution R.

[0038] Specifically, this calculation is based on the principles of optical diffraction and interference. When the light beam passes through the diffraction turn grating 3, light of different wavelengths will be diffracted to different degrees, thus forming a spectrum. The resolution R represents the minimum wavelength difference that the spectrometer can distinguish, that is, the difference between the wavelengths of two adjacent spectral lines. By determining the duty cycle FF and the grating period d, we can calculate the width a of the light-transmitting part of the diffraction turn grating 3, which helps to further optimize the design of the diffraction turn grating 3 and improve its resolution. In terms of process implementation, once the resolution R is determined, we can design and manufacture the diffraction turn grating 3 according to this parameter.

[0039] Reference Figure 3 In step S3, the calculation formula of the dispersion rate in the turning zone is as follows: Among them, D i represents the dispersion rate; dl represents the distance between adjacent spectral lines; dλ represents the difference in wavelength between adjacent spectral lines. The grating constant D is inferred from the calculation of the dispersion rate, and thus the width of the diffraction turning grating 3 is calculated. The calculation formula for the width of the diffraction turning grating 3 is as follows: W1=ND; Wherein, W1 represents the width of the diffraction turning grating 3; N represents the total number of lines of the diffraction turning grating 3; D represents the length of the minimum repetition period on the diffraction turning grating 3. The line density of the diffraction turning grating 3 is obtained by the above calculation: Thereby, the diffraction efficiency of the diffraction turning grating 3 is obtained.

[0040] Specifically, we first need to calculate the dispersion rate D in the turning zone: i , dispersion rate D iIt refers to the ratio between the distance between adjacent spectral lines and the difference in wavelength between adjacent spectral lines. Through measurement and calculation, we can get 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 to describe the grating structure. It indicates the length of the minimum repetition period on the grating. According to the calculation formula of the dispersion rate, we can substitute the known dispersion rate into the formula to get the value of the grating constant D. Then, we can calculate the width of the diffraction turn grating 3 according to the grating constant D. The diffraction turn grating 3 is an important component used in optical systems. Its width has an important influence on the diffraction efficiency of the system. According to the diffraction turn grating 3 According to the width calculation formula, we only need to know the total number of lines N and the grating constant D of the diffraction turn grating 3 to calculate the width of the diffraction turn grating 3. Finally, through the line density of the diffraction turn grating 3 obtained by the above calculation, we can further derive the diffraction efficiency of the diffraction turn grating 3. The diffraction efficiency is an important indicator to measure the performance of optical components. It reflects the diffraction ability of the optical component to the incident light. By calculating the line density of the diffraction turn grating 3, we can get the specific value of its diffraction efficiency. In summary, by calculating the dispersion rate, grating constant, width of the diffraction turn grating 3 and the diffraction efficiency, we can fully understand and evaluate the performance characteristics of the diffraction turn grating 3.

[0041] Reference Figure 3 and Figure 4 In step S4, the process flow of the surface relief process of the diffraction turning grating 3 is as follows: B1. Motherboard preparation: a positive photoresist layer is evenly coated on the turning area of ​​the waveguide plate 1, and the thickness of the positive photoresist layer is controlled to be 180 mm; B2. Exposure and development: performing contact exposure and development processing on the waveguide plate 1 with a uniform photoresist mask to obtain a waveguide plate 1 with a photoresist mask in the turning area, and then performing interference exposure and development on the turning area to obtain a waveguide plate 1 with a grating mask in the turning area; B3. Etching treatment: using trifluoromethane gas for dry etching to form a diffraction turning grating 3 in the turning area.

[0042] Specifically, the waveguide plate 1 is thoroughly cleaned with 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, a photolithography mask plate is used to shield the target structure area, the waveguide plate 1 with a uniform photoresist mask is subjected to contact exposure and development treatment to obtain a waveguide plate 1 with a photoresist mask in the target structure area, and then the waveguide plate 1 with a photoresist mask in the target structure area is subjected to interference exposure and development to obtain a waveguide plate 1 with a grating mask in the target structure area, and a suitable etching method is selected according to the material of the waveguide plate 1, which is generally made of quartz glass material, and trifluoromethane gas is often used for dry etching, and parameters such as etching speed, depth and side wall inclination angle need to be strictly controlled during the etching process.

[0043] The implementation principle of the embodiment of the present application is as follows: the refraction-diffraction hybrid two-dimensional optical waveguide design combines the two optical phenomena of refraction and diffraction to achieve effective control of light waves. The design forms a specific grating structure on the waveguide plate 1 and utilizes the interference and diffraction effects of light to achieve the purpose of light beam coupling, turning and output. The entire design process includes the steps of setting the light beam transmission path, forming the grating, calculating the turning zone parameters, and implementing the surface relief process. According to the width W of the waveguide plate 1, the wavelength λ that can pass through, and the effective refractive index n eff, the thickness h and refractive index n of the waveguide plate, as well as the incident angle α and the diffraction angle β, the positions and sizes of the coupling-in area, the turning area and the coupling-out area are determined by a series of calculation formulas. These parameters ensure that the transmission path of the light beam in the waveguide plate 1 meets the design requirements and reduces energy loss. In the coupling-in area and the coupling-out area, an array grating is formed by photolithography technology. This step involves substrate spin coating of photoresist, ultraviolet exposure, development treatment, reactive ion beam etching, coating and polishing, and finally the required grating structure is obtained. These gratings are used for coupling and output of light beams, and their precise geometric parameters are It is very important for the transmission efficiency of the light beam. The grating period d of the turning zone is determined by the diffraction order n, the wavelength λ of the incident light, the incident angle α and the diffraction angle β. The width a of the light-transmitting part 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 of the diffraction turning 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 performance of the grating in the turning zone. A positive photoresist layer is evenly coated at the turning zone position, and a photoresist mask is formed by contact exposure and development. Subsequently, interference exposure and development are performed to obtain a waveguide plate 1 with a grating mask. Finally, trifluoromethane gas is used for dry etching to form a diffraction turning grating 3. The precise control of this process step is very important for achieving high diffraction efficiency and low loss. The above design realizes the precise setting of the light beam transmission path and the high-precision production of the grating structure through precise calculation and fine process control. At the same time, the optimized grating parameters and process steps reduce the energy loss of the light beam during transmission and improve the transmission efficiency.

[0044] The embodiments of this specific implementation are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. The same components are marked with the same reference numerals. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for producing a refractive-diffractive hybrid two-dimensional optical waveguide, characterized in that: The following steps are involved: S1, setting a beam transmission path, and determining a coupling-in region, a turning region, and a coupling-out region on a waveguide plate (1); S2, forming an arrayed in-coupling grating (2) and an arrayed out-coupling grating (4) in the in-coupling area and the out-coupling area defined by the waveguide plate (1) by using an arrayed waveguide grating process; S3, determining the grating period, light-transmitting portion width, grating width, resolution and dispersion rate of the turning zone based on the preset calculation rules of the turning zone; S4. Using the calculated data of S3, a diffraction turning grating (3) is formed in the turning area defined by the waveguide plate (1) through a surface relief process.

2. The method for producing a refractive-diffractive hybrid two-dimensional optical waveguide according to claim 1, characterized in that: In step S1, the waveguide plate (1) is subjected to calculation to determine parameters, wherein the calculation formula is as follows: Wherein, W represents the width of the waveguide plate (1); λ represents the wavelength that can pass through; n eff 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, and the coupling-in region, the turning region and the coupling-out region are divided according to the calculation results of the above formula.

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

4. The method for producing a refractive-diffractive hybrid two-dimensional optical waveguide according to claim 3, characterized in that: In step S3, the calculation formula of the grating period of the transition region is as follows: Wherein, 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 stripes. The grating stripe spacing of the diffraction turning grating (3) is determined by calculation using the above formula.

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

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

7. The method for producing a refractive-diffractive hybrid two-dimensional optical waveguide according to claim 1, characterized in that: In step S3, the calculation formula of the dispersion rate in the turning zone is as follows: Among them, D i represents the dispersion rate; dl represents the distance between adjacent spectral lines; dλ represents the difference in wavelength between adjacent spectral lines. The grating constant D is inferred from the calculation of the dispersion rate, thereby calculating the width of the diffraction turning grating (3). The calculation formula for the width of the diffraction turning grating (3) is as follows: W1=ND; Wherein, W1 represents the width of the diffraction turning grating (3); N represents the total number of lines of the diffraction turning grating (3); D represents the length of the minimum repetition period on the diffraction turning grating (3). The line density of the diffraction turning grating (3) is obtained by the above calculation: Thereby, the diffraction efficiency of the diffraction turning grating (3) is obtained.

8. 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 turning grating (3) is as follows: B1. Motherboard preparation: a positive photoresist layer is uniformly coated on the turning area of ​​the waveguide plate (1), wherein the thickness of the positive photoresist layer is controlled to be 180 mm; B2, exposure and development: performing contact exposure and development treatment on the waveguide plate (1) with a uniform photoresist mask to obtain a waveguide plate (1) with a photoresist mask in the turning region, and then performing interference exposure and development on the turning region to obtain a waveguide plate (1) with a grating mask in the turning region; B3. Etching treatment: using trifluoromethane gas to perform dry etching to form the diffraction turning grating (3) in the turning area.

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