WO2024125102A1

WO2024125102A1 - Two-dimensional grating structure, pupil expansion structure, out-coupling structure, and diffractive optical waveguide

Info

Publication number: WO2024125102A1
Application number: PCT/CN2023/127091
Authority: WO
Inventors: 张雅琴; 楼歆晔
Original assignee: 上海鲲游科技有限公司
Priority date: 2022-12-16
Filing date: 2023-10-27
Publication date: 2024-06-20

Abstract

A two-dimensional grating structure and a diffractive optical waveguide (200). The two-dimensional grating structure is used for a pupil expansion structure (202) and/or an out-coupling structure (203) of the diffractive optical waveguide, and comprises: a plurality of grating units periodically arranged in at least two directions, wherein the plurality of grating units periodically arranged in at least two directions are configured such that the propagation path of a light beam in the diffractive optical waveguide is only affected by a periodic structure formed by the plurality of grating units in one of the directions. The diffractive optical waveguide (200) comprises: a waveguide substrate (204) and an in-coupling structure (201), and the out-coupling structure (203) that are provided on the surface of or inside the waveguide substrate (204), or the in-coupling structure (201), the pupil expansion structure (202), and the out-coupling structure (203) that are provided on the surface of or inside the waveguide substrate (204). The degree of freedom of modulating the diffraction efficiency by modulating the duty cycle is optimized by increasing the periodic dimension of a grating structure, and the influence of added periodic structures in other dimensions on an original light beam propagation path can also be avoided.

Description

二维光栅结构、扩瞳结构、耦出结构以及衍射光波导Two-dimensional grating structure, pupil expansion structure, outcoupling structure and diffractive optical waveguide

技术领域Technical Field

本发明涉及光波导领域，尤其涉及一种二维光栅结构、扩瞳结构、耦出结构以及衍射光波导。The present invention relates to the field of optical waveguides, and in particular to a two-dimensional grating structure, a pupil expansion structure, an outcoupling structure and a diffraction optical waveguide.

背景技术Background technique

增强现实(AR)是一种将真实世界和虚拟信息相融合的技术，AR显示***通常包括微型投影仪和光学显示屏，将微型显示器提供的虚拟内容通过光学显示屏投射到人眼中，用户同时透过光学显示屏看到真实世界。Augmented reality (AR) is a technology that integrates the real world and virtual information. The AR display system usually includes a micro projector and an optical display screen. The virtual content provided by the micro display is projected into the human eye through the optical display screen, and the user sees the real world through the optical display screen at the same time.

光波导是光学显示屏的一种实现路径，目前市面上光波导通常被分为几何阵列波导和衍射光波导，衍射光波导又分为体全息波导和表面浮雕光栅波导，其中表面浮雕光栅波导以其极高的设计自由度在众多方案中具有明显的优势。均匀性是评价衍射光波导性能的关键指标之一，波导设计中通常通过对光栅参数(比如光栅深度或者光栅占空比等)调制优化均匀性。Optical waveguides are a way to realize optical display screens. Currently, optical waveguides on the market are usually divided into geometric array waveguides and diffraction waveguides. Diffraction waveguides are further divided into volume holographic waveguides and surface relief grating waveguides. Among them, surface relief grating waveguides have obvious advantages in many solutions due to their extremely high design freedom. Uniformity is one of the key indicators for evaluating the performance of diffraction waveguides. In waveguide design, uniformity is usually optimized by modulating grating parameters (such as grating depth or grating duty cycle).

目前表面浮雕光栅波导最常用的架构为一维耦入光栅、一维扩瞳光栅以及一维耦出光栅组合的架构。在这种架构下，通过调制光栅深度调制优化均匀性方式理论上具有较好的效果，但制作工艺较为复杂；通过调制光栅占空比调制优化均匀性方式在相同深度下调制占空比有一定的调制能力，但要实现较大的调制范围，通常需要较为极限的线宽，工艺制作难度。At present, the most commonly used architecture of surface relief grating waveguide is the combination of one-dimensional coupling-in grating, one-dimensional pupil expansion grating and one-dimensional coupling-out grating. In this architecture, the method of optimizing uniformity by modulating the grating depth modulation has a good effect in theory, but the manufacturing process is relatively complicated; the method of optimizing uniformity by modulating the grating duty cycle modulation has a certain modulation capability at the same depth, but to achieve a larger modulation range, a relatively extreme line width is usually required, and the manufacturing process is difficult.

因此，本领域技术人员希望设计一种光栅结构来优化前述架构，进而能够在调制衍射效率的自由度上有所提高，同时还能降低工艺制作难度。Therefore, those skilled in the art hope to design a grating structure to optimize the aforementioned architecture, thereby improving the degree of freedom in modulating the diffraction efficiency while reducing the difficulty of process manufacturing.

发明内容Summary of the invention

本发明提供一种二维光栅结构、扩瞳结构、耦出结构以及衍射光波导，以解决在通过调制占空比来优化均匀性时自由度受限以及工艺制作难度高的问题。The present invention provides a two-dimensional grating structure, a pupil expansion structure, a coupling-out structure and a diffraction optical waveguide to solve the problems of limited freedom and high difficulty in process manufacturing when optimizing uniformity by modulating the duty cycle.

根据本发明的第一方面，提供了一种二维光栅结构，用于衍射光波导的扩瞳结构和/或耦出结构，所述二维光栅结构包括：According to a first aspect of the present invention, a two-dimensional grating structure is provided, which is used for a pupil expansion structure and/or an outcoupling structure of a diffractive optical waveguide, and the two-dimensional grating structure comprises:

至少在两个方向上周期性排布的多个光栅单元，其中，在所述至少两个方向上周期性排布的所述多个光栅单元被配置为：使得光束在所述衍射光波导中的传播路径仅被所述多个光栅单元在其中一个方向上形成的周期性结构影响。A plurality of grating units are periodically arranged in at least two directions, wherein the plurality of grating units periodically arranged in the at least two directions are configured so that a propagation path of the light beam in the diffraction optical waveguide is only affected by the periodic structure formed by the plurality of grating units in one direction.

可选的，所述其中一个方向为目标方向，所述至少两个方向中除所述目标方向外的方向为其他方向，所述多个光栅单元在所述其它方向上形成的周期性结构被配置为：所述其它方向上形成的周期性结构的周期适配于所述光束的波长以及所述衍射光波导的波导基底的折射率，以使得所述光束在所述衍射光波导中的传播路径不被所述其它方向上形成的周期性结构影响。Optionally, one of the directions is a target direction, and the directions other than the target direction among the at least two directions are other directions, and the periodic structures formed by the multiple grating units in the other directions are configured as follows: the period of the periodic structures formed in the other directions is adapted to the wavelength of the light beam and the refractive index of the waveguide substrate of the diffractive optical waveguide, so that the light beam The propagation path in the diffractive optical waveguide is not affected by the periodic structure formed in the other directions.

可选的，所述多个光栅单元在所述其他方向中的第i个方向上形成的周期性结构的周期被配置为可选范围内的最大值，所述可选范围表征了所述光束在所述衍射光波导中的传播路径仅被所述多个光栅单元在所述目标方向上形成的周期性结构影响时，所述多个光栅单元在所述第i个方向上形成的周期性结构的周期的取值。Optionally, the period of the periodic structure formed by the multiple grating units in the i-th direction among the other directions is configured as a maximum value within an optional range, and the optional range represents the value of the period of the periodic structure formed by the multiple grating units in the i-th direction when the propagation path of the light beam in the diffraction optical waveguide is only affected by the periodic structure formed by the multiple grating units in the target direction.

可选的，所述多个光栅单元在其它方向上形成的周期性结构还被配置为：使得光束在所述衍射光波导中的衍射效率被所述多个光栅单元在所述目标方向和所述其他方向上形成的周期性结构共同影响。Optionally, the periodic structures formed by the multiple grating units in other directions are further configured to: enable the diffraction efficiency of the light beam in the diffraction optical waveguide to be jointly affected by the periodic structures formed by the multiple grating units in the target direction and the other directions.

可选的，所述二维光栅结构的不同位置的影响所述二维光栅结构的衍射效率的光栅参数不同，以调节所述光束在所述二维光栅结构作用下扩瞳和/或耦出的均匀性。Optionally, different positions of the two-dimensional grating structure have different grating parameters that affect the diffraction efficiency of the two-dimensional grating structure, so as to adjust the uniformity of pupil expansion and/or outcoupling of the light beam under the action of the two-dimensional grating structure.

可选的，所述二维光栅结构被配置为：通过配置所述二维光栅结构的不同区域的光栅占空比，以使得在所述衍射光波导中，沿光束传播的方向，所述二维光栅结构的衍射效率逐渐增大，以调节光束在所述二维光栅结构作用下扩瞳或者耦出的均匀性。Optionally, the two-dimensional grating structure is configured as follows: by configuring the grating duty ratio of different regions of the two-dimensional grating structure, so that in the diffraction waveguide, along the direction of light beam propagation, the diffraction efficiency of the two-dimensional grating structure gradually increases, so as to adjust the uniformity of pupil expansion or outcoupling of the light beam under the action of the two-dimensional grating structure.

根据本发明的第二方面，提供了一种扩瞳结构，包括本发明第一方面任一项所述的光栅结构。According to a second aspect of the present invention, there is provided a pupil expansion structure, comprising the grating structure as described in any one of the first aspects of the present invention.

可选的，所述扩瞳结构还包括一维光栅结构，且所述扩瞳结构中沿着光束传播的方向转折效率依次增大。Optionally, the pupil expansion structure further includes a one-dimensional grating structure, and the turning efficiency in the pupil expansion structure increases successively along the direction of light beam propagation.

根据本发明的第三方面，提供了一种耦出结构，包括本发明第一方面所述的光栅结构。According to a third aspect of the present invention, there is provided a coupling-out structure, comprising the grating structure described in the first aspect of the present invention.

可选的，所述耦出结构还包括一维光栅结构，且所述耦出结构中沿着光束传播的方向耦出效率依次增大。Optionally, the outcoupling structure further includes a one-dimensional grating structure, and the outcoupling efficiency in the outcoupling structure increases successively along the direction of light beam propagation.

根据本发明的第四方面，提供了一种衍射光波导，包括：According to a fourth aspect of the present invention, there is provided a diffractive optical waveguide, comprising:

波导基底；waveguide substrate;

设置于所述波导基底表面或内部的耦入结构和耦出结构，或者，设置于所述波导基底表面或者内部的耦入结构、扩瞳结构和耦出结构；所述耦入结构用于将图像光束耦入所述波导基底并在所述波导基底内传输，所述扩瞳结构用于将图像光束扩展传输至所述耦出结构，所述耦出结构用于将所述波导基底内传输的图像光束从所述波导基底中衍射耦出；A coupling-in structure and a coupling-out structure are arranged on the surface or inside of the waveguide substrate, or a coupling-in structure, a pupil expansion structure and a coupling-out structure are arranged on the surface or inside of the waveguide substrate; the coupling-in structure is used to couple the image light beam into the waveguide substrate and transmit it in the waveguide substrate, the pupil expansion structure is used to expand the image light beam and transmit it to the coupling-out structure, and the coupling-out structure is used to diffract and couple the image light beam transmitted in the waveguide substrate out of the waveguide substrate;

所述扩瞳结构和/或所述耦出结构至少包括一二维光栅结构，其中所述二维光栅结构包括：至少在两个方向上周期性排布的多个光栅单元，其中，在所述至少两个方向上周期性排布的所述多个光栅单元被配置为：使得图像光束在所述衍射光波导中的传播路径仅被所述多个光栅单元在其中一个方向上形成的周期性结构影响。The pupil expansion structure and/or the outcoupling structure includes at least a two-dimensional grating structure, wherein the two-dimensional grating structure includes: a plurality of grating units arranged periodically in at least two directions, wherein the plurality of grating units arranged periodically in the at least two directions are configured so that a propagation path of the image light beam in the diffraction optical waveguide is only affected by the periodic structure formed by the plurality of grating units in one direction.

可选的，所述多个光栅单元在其它方向上形成的周期性结构被配置为：其它方向上形成的周期性结构的周期适配于光束的波长以及所述波导基底的折射率，以使得光束在所述衍射光波导中的传播路径不被其它方向上形成的周期性结构影响；其中，所述其中一个方向为目标方向，所述其他方向表征了所述至少两个方向中除所述目标方向外的方向。Optionally, the periodic structures formed by the plurality of grating units in other directions are configured as follows: the period of the periodic structures formed in other directions is adapted to the wavelength of the light beam and the refractive index of the waveguide substrate, so that the propagation path of the light beam in the diffraction light waveguide is not affected by the periodic structures formed in other directions. Periodic structural influence; wherein, one of the directions is a target direction, and the other directions represent directions of the at least two directions except the target direction.

可选的，所述衍射光波导包括耦入结构、扩瞳结构和耦出结构，所述扩瞳结构和/或所述耦出结构包括所述二维光栅结构，在所述扩瞳结构中的目标方向为第一目标方向，在所述耦出结构中的目标方向为第二目标方向，所述第一目标方向和所述第二目标方向表征不同的方向。Optionally, the diffraction optical waveguide includes a coupling-in structure, a pupil expansion structure and a coupling-out structure, the pupil expansion structure and/or the coupling-out structure include the two-dimensional grating structure, the target direction in the pupil expansion structure is a first target direction, and the target direction in the coupling-out structure is a second target direction, and the first target direction and the second target direction represent different directions.

可选的，所述多个光栅单元在其它方向中的第i个方向上形成的周期性结构的周期被配置为符合以下公式：
Optionally, the period of the periodic structure formed by the plurality of grating units in the i-th direction in other directions is configured to comply with the following formula:

其中，(K_x0，K_y0)为光束被所述多个光栅单元在第i个方向上形成的周期性结构作用前的K矢量坐标，m为衍射级次，n为所述波导基底的折射率，λ为光束的波长，d_i为所述多个光栅单元在第i个方向上形成的周期性结构的周期，θ是所述多个光栅单元在第i个方向上形成的周期性结构的光栅矢量与矢量坐标系中x轴的夹角，(K_x0+m*(2π/d_i)cosθ，K_y0+m*(2π/d_i)sinθ)为光束被所述多个光栅单元在第i个方向上形成的周期性结构作用后的K矢量坐标。Wherein, ( _Kx0 , _Ky0 ) is the K vector coordinate of the light beam before being acted upon by the periodic structure formed by the multiple grating units in the i-direction, m is the diffraction order, n is the refractive index of the waveguide substrate, λ is the wavelength of the light beam, d _i is the period of the periodic structure formed by the multiple grating units in the i-direction, θ is the angle between the grating vector of the periodic structure formed by the multiple grating units in the i-direction and the x-axis in the vector coordinate system, and ( _Kx0 +m*(2π/d _i )cosθ, _Ky0 +m*(2π/d _i )sinθ) is the K vector coordinate of the light beam after being acted upon by the periodic structure formed by the multiple grating units in the i-direction.

可选的，所述多个光栅单元在第i个方向上形成的周期性结构的周期被配置为可选范围内的最大值，所述可选范围表征了光束在所述衍射光波导中的传播路径仅被所述多个光栅单元在其中一个方向上形成的周期性结构影响时，所述多个光栅单元在第i个方向上形成的周期性结构的周期的取值。Optionally, the period of the periodic structure formed by the multiple grating units in the i-th direction is configured as a maximum value within an optional range, and the optional range represents the value of the period of the periodic structure formed by the multiple grating units in the i-th direction when the propagation path of the light beam in the diffraction optical waveguide is only affected by the periodic structure formed by the multiple grating units in one direction.

可选的，所述多个光栅单元在其它方向上形成的周期性结构还被配置为：使得光束在所述衍射光波导中的衍射效率被所述多个光栅单元在其他方向上形成的周期性结构共同影响。Optionally, the periodic structures formed by the multiple grating units in other directions are further configured to: enable the diffraction efficiency of the light beam in the diffraction optical waveguide to be jointly affected by the periodic structures formed by the multiple grating units in other directions.

可选的，所述二维光栅结构的不同位置的影响所述二维光栅结构的衍射效率的光栅参数不同，以调节经过所述二维光栅结构作用后的光束的均匀性。Optionally, grating parameters affecting the diffraction efficiency of the two-dimensional grating structure are different at different positions of the two-dimensional grating structure, so as to adjust the uniformity of the light beam after being acted upon by the two-dimensional grating structure.

可选的，所述二维光栅结构的不同位置的光栅占空比不同，以调节经过所述二维光栅结构作用后的光束的均匀性。Optionally, the grating duty cycles at different positions of the two-dimensional grating structure are different, so as to adjust the uniformity of the light beam after being acted upon by the two-dimensional grating structure.

可选的，所述二维光栅结构被配置为：通过配置所述二维光栅结构的不同区域的光栅占空比，以使得在所述衍射光波导中，沿光束传播的方向，所述二维光栅结构的衍射效率逐渐增大，以调节经过所述二维光栅结构作用后的光束的均匀性。Optionally, the two-dimensional grating structure is configured as follows: by configuring the grating duty ratio of different regions of the two-dimensional grating structure, so that in the diffraction optical waveguide, along the direction of light beam propagation, the diffraction efficiency of the two-dimensional grating structure gradually increases, so as to adjust the uniformity of the light beam after passing through the two-dimensional grating structure.

可选的，所述衍射光波导包括耦入结构、扩瞳结构和耦出结构；其中，所述扩瞳结构包括二维光栅结构，所述扩瞳结构中的二维光栅结构的不同区域的光栅占空比被调制，以使得在所述衍射光波导中，沿所述图像光束传播的方向，所述扩瞳结构的转折效率逐渐增大，和/或，所述耦出结构包括二维光栅结构，所述耦出结构中的二维光栅结构的不同区域的光栅占空比，以使得在所述衍射光波导中，沿所述图像光束传播的方向，所述耦出结构的耦出效率逐渐增大。Optionally, the diffraction optical waveguide includes a coupling-in structure, a pupil expansion structure and a coupling-out structure; wherein the pupil expansion structure includes a two-dimensional grating structure, and the grating duty ratio of different regions of the two-dimensional grating structure in the pupil expansion structure is modulated so that in the diffraction optical waveguide, along the propagation direction of the image light beam, the turning efficiency of the pupil expansion structure gradually increases, and/or, the coupling-out structure includes a two-dimensional grating structure, and the grating duty ratio of different regions of the two-dimensional grating structure in the coupling-out structure is modulated so that in the diffraction optical waveguide, along the propagation direction of the image light beam, the coupling-out efficiency of the coupling-out structure gradually increases.

可选的，所述扩瞳结构包括二维光栅结构和一维光栅结构，所述扩瞳结构中二维光栅结构的不同区域的光栅占空比以及一维光栅结构的光栅占空比被调制，以使得在所述衍射光波导中，沿所述图像光束传播的方向，所述扩瞳结构的转折效率逐渐增大。Optionally, the pupil expansion structure includes a two-dimensional grating structure and a one-dimensional grating structure. The grating duty ratios of different regions of the two-dimensional grating structure and the grating duty ratio of the one-dimensional grating structure in the structure are modulated so that in the diffraction optical waveguide, along the propagation direction of the image light beam, the turning efficiency of the pupil expansion structure gradually increases.

可选的，所述耦出结构包括二维光栅结构和一维光栅结构，所述耦出结构中二维光栅结构的不同区域的光栅占空比以及一维光栅结构的光栅占空比被调制，以使得在所述衍射光波导中，沿所述图像光束传播的方向，所述耦出结构的耦出效率逐渐增大。Optionally, the out-coupling structure includes a two-dimensional grating structure and a one-dimensional grating structure, and the grating duty ratio of different regions of the two-dimensional grating structure and the grating duty ratio of the one-dimensional grating structure in the out-coupling structure are modulated so that in the diffraction optical waveguide, along the propagation direction of the image light beam, the out-coupling efficiency of the out-coupling structure gradually increases.

可选的，所述扩瞳结构的光栅深度与所述耦出结构的光栅深度一致。Optionally, the grating depth of the pupil expansion structure is consistent with the grating depth of the outcoupling structure.

可选的，所述衍射光波导包括耦入结构和耦出结构，所述耦出结构分为第一耦出结构、第二耦出结构和第三耦出结构，所述第二耦出结构位于所述第一耦出结构和所述第三耦出结构之间，所述第一耦出结构和所述第三耦出结构包括所述二维光栅结构。Optionally, the diffraction optical waveguide includes a coupling-in structure and a coupling-out structure, the coupling-out structure is divided into a first coupling-out structure, a second coupling-out structure and a third coupling-out structure, the second coupling-out structure is located between the first coupling-out structure and the third coupling-out structure, and the first coupling-out structure and the third coupling-out structure include the two-dimensional grating structure.

可选的，所述第一耦出结构和所述第三耦出结构还包括一维光栅结构，所述第一耦出结构和所述第三耦出结构中所述二维光栅结构的不同区域的光栅占空比以及所述一维光栅结构的光栅占空比被调制，以使得在所述衍射光波导中，沿所述图像光束传播的方向，所述第一耦出结构和所述第三耦出结构的衍射效率逐渐增大。Optionally, the first out-coupling structure and the third out-coupling structure also include a one-dimensional grating structure, and the grating duty ratios of different regions of the two-dimensional grating structure in the first out-coupling structure and the third out-coupling structure and the grating duty ratio of the one-dimensional grating structure are modulated so that in the diffraction optical waveguide, along the propagation direction of the image light beam, the diffraction efficiency of the first out-coupling structure and the third out-coupling structure gradually increases.

可选的，在所述耦出结构中，所述多个光栅单元在其中一个方向上形成的周期性结构与所述多个光栅单元在其它方向上形成的周期性结构的矢量方向形成的角度的取值为90°。Optionally, in the out-coupling structure, an angle formed by a periodic structure formed by the multiple grating units in one direction and a vector direction of a periodic structure formed by the multiple grating units in another direction is 90°.

可选的，所述耦出结构还包括一维光栅结构，且所述耦出结构中沿着光束传播的方向衍射效率依次增大。Optionally, the out-coupling structure further includes a one-dimensional grating structure, and the diffraction efficiency in the out-coupling structure increases successively along the direction of light beam propagation.

可选的，在所述扩瞳光栅中，所述多个光栅单元在其中一个方向上形成的周期性结构与所述多个光栅单元在其它方向上形成的周期性结构的矢量方向之间形成的角度的取值为45°。Optionally, in the pupil expansion grating, an angle formed by a periodic structure formed by the multiple grating units in one direction and a vector direction of a periodic structure formed by the multiple grating units in other directions is 45°.

可选的，所述扩瞳结构还包括一维光栅结构，且所述扩瞳结构中沿着光束传播的方向衍射效率依次增大。Optionally, the pupil expansion structure further includes a one-dimensional grating structure, and the diffraction efficiency in the pupil expansion structure increases successively along the direction of light beam propagation.

根据本发明的第五方面，提供了一种AR设备，包括本发明第四方面的任一项所述的衍射光波导。According to a fifth aspect of the present invention, there is provided an AR device, comprising the diffractive optical waveguide according to any one of the fourth aspect of the present invention.

本发明提供的一种包括多个光栅单元的二维光栅结构，这些光栅单元在至少两个方向上周期性排布，并被配置为：用于衍射光波导的扩瞳结构和/或耦出结构时，使得光束在衍射光波导中的传播路径仅被这些光栅单元在其中一个方向上形成的周期性结构影响，以用于控制光束在波导基底内的传播路径；而其他方向形成的周期性结构不影响光束在二维光栅结构中的传播方向。可见，本发明提供的二维光栅结构用于衍射光波导的扩瞳结构和/或耦出结构时，相较于现有的一维光栅结构用于衍射光波导的扩瞳结构和/或耦出结构的场景，既可以通过配置使得光束在衍射光波导中的传播路径不受影响，而且还能通过光栅单元的排布来极大提高通过调制占空比来优化均匀性自由度，另外，通过光栅占空比优化自由度的提升还能减小工艺难度和工艺成本。The present invention provides a two-dimensional grating structure including a plurality of grating units, wherein these grating units are periodically arranged in at least two directions and are configured as follows: when used for the pupil expansion structure and/or out-coupling structure of a diffraction optical waveguide, the propagation path of the light beam in the diffraction optical waveguide is only affected by the periodic structure formed by these grating units in one direction, so as to control the propagation path of the light beam in the waveguide substrate; while the periodic structures formed in other directions do not affect the propagation direction of the light beam in the two-dimensional grating structure. It can be seen that when the two-dimensional grating structure provided by the present invention is used for the pupil expansion structure and/or out-coupling structure of a diffraction optical waveguide, compared with the scenario in which the existing one-dimensional grating structure is used for the pupil expansion structure and/or out-coupling structure of a diffraction optical waveguide, the propagation path of the light beam in the diffraction optical waveguide can be not only configured to be unaffected, but also the degree of freedom for optimizing uniformity by modulating the duty cycle can be greatly improved through the arrangement of the grating units. In addition, the improvement of the degree of freedom in optimizing the grating duty cycle can also reduce the process difficulty and cost.

进一步地，本发明提供的一种衍射光波导，其扩瞳结构和/或耦出结构中至少包括一二维光栅结构；其中，二维光栅结构在至少两个方向上周期性排布的多个光栅单元被配置为：使得光束在衍射光波导中的传播路径仅被多个光栅单元在其中一个方向上形成的周期性结构影响，以用于控制光束在波导基底内的传播路径；而其他方向形成的周期性结构不影响光束在二维光栅中的传播方向。这使得本发明提供的衍射光波导的扩瞳结构和/或耦出结构通过增加周期性结构的维度来极大提高通过调制占空比优化均匀性的自由度，而且不会因为周期性结构维度的增加引入新的光束传播路径而加大优化均匀性的复杂度，另外，通过光栅占空比优化自由度的提升还能减小工艺难度和工艺成本。Furthermore, the present invention provides a diffraction optical waveguide, wherein the pupil expansion structure and/or coupling-out structure of the diffraction optical waveguide at least includes a two-dimensional grating structure; wherein the two-dimensional grating structure has a plurality of grating units periodically arranged in at least two directions and configured such that the propagation path of the light beam in the diffraction optical waveguide is only affected by the periodic structure formed by the plurality of grating units in one direction, so as to control the propagation path of the light beam in the waveguide substrate; and the periodic structures formed in other directions do not affect the propagation direction of the light beam in the two-dimensional grating. This allows the pupil expansion structure and/or coupling-out structure of the diffraction optical waveguide provided by the present invention to greatly improve the degree of freedom of optimizing uniformity by modulating the duty cycle by increasing the dimension of the periodic structure, and does not increase the complexity of optimizing uniformity by introducing a new light beam propagation path due to the increase in the dimension of the periodic structure. In addition, the improvement of the degree of freedom of optimizing the grating duty cycle can also reduce the process difficulty and process cost.

附图说明BRIEF DESCRIPTION OF THE DRAWINGS

为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

图1是由一维光栅构成的衍射光波导架构与光栅布置示意图；FIG1 is a schematic diagram of a diffraction optical waveguide structure and grating arrangement consisting of a one-dimensional grating;

图2是一维光栅结构的衍射效率随占空比变化的曲线示意图；FIG2 is a schematic diagram of a curve showing the diffraction efficiency of a one-dimensional grating structure as a function of duty cycle;

图3是一维光栅结构及二维光栅结构的占空比示意图；FIG3 is a schematic diagram of the duty cycle of a one-dimensional grating structure and a two-dimensional grating structure;

图4是本发明一具体实施例中二维光栅结构的衍射效率随占空比变化的曲线示意图；FIG4 is a schematic diagram of a curve showing the diffraction efficiency of a two-dimensional grating structure as a function of duty cycle in a specific embodiment of the present invention;

图5是本发明一实施例中提供的二维光栅结构中主光栅和辅助光栅的示意图；5 is a schematic diagram of a main grating and an auxiliary grating in a two-dimensional grating structure provided in one embodiment of the present invention;

图6是光束在衍射光波导中传播的K域示意图；FIG6 is a schematic diagram of the K domain of a light beam propagating in a diffractive optical waveguide;

图7是本发明一实施例中提供的衍射光波导的示意图；FIG7 is a schematic diagram of a diffractive optical waveguide provided in one embodiment of the present invention;

图8是本发明一具体实施例中衍射光波导的示意图；FIG8 is a schematic diagram of a diffractive optical waveguide in a specific embodiment of the present invention;

图9是图像光束在图8所示的衍射光波导中传输的传播的K域图；FIG9 is a K-domain diagram of the propagation of an image beam transmitted in the diffractive optical waveguide shown in FIG8 ;

图10是本发明另一具体实施例中衍射光波导的示意图；FIG10 is a schematic diagram of a diffractive optical waveguide in another specific embodiment of the present invention;

图11是图像光束在图10所示的衍射光波导中传输的传播的K域图。FIG. 11 is a K-domain diagram of the propagation of an image beam transmitted in the diffractive optical waveguide shown in FIG. 10 .

具体实施方式Detailed ways

下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行The technical solutions in the embodiments of the present invention will be described below in conjunction with the accompanying drawings in the embodiments of the present invention.

清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。Clearly and completely described, it is obvious that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

本发明的说明书和权利要求书及上述附图中的术语“第一”、“第二”、“第三”、“第四”等(如果存在)是用于区别类似的对象，而不必用于描述特定的顺序或先后次序。应该理解这样使用的数据在适当情况下可以互换，以便这里描述的本发明的实施例能够以除了在这里图示或描述的那些以外的顺序实施。此外，术语“包括”和“具有”以及他们的任何变形，意图在于覆盖不排他的包含，例如，包含了一系列步骤或单元的过程、方法、***、产品或设备不必限于清楚地列出的那些步骤或单元，而是可包括没有清楚地列出的或对于这些过程、方法、产品或设备固有的其它步骤或单元。The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present invention and the above drawings are used to distinguish similar objects, but not necessarily to describe a specific order or sequence. It should be understood that the terms used in this way can be used as appropriate. Interchangeable, so that the embodiments of the invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

可以理解，均匀性是评价衍射光波导性能的关键指标之一，其包括FOV均匀性和eyebox均匀性。常用的一种优化衍射光波导均匀性的方式是：对衍射光波导中扩瞳光栅和/或耦出光栅的衍射效率进行调制；具体包括：将扩瞳光栅和/或耦出光栅的衍射效率调制为：随着光束传播距离的增加而增大，虽然光束每次遇到扩瞳光栅和/或耦出光栅时会有能量损失，然而由于衍射效率会随着光束的传播而增大，因而，光束沿着衍射光波导内传播方向在不同位置仍然能保持均匀。常用的调制光栅衍射效率的方式为调制光栅的参数，比如光栅深度或者光栅占空比等。It can be understood that uniformity is one of the key indicators for evaluating the performance of diffraction waveguides, which includes FOV uniformity and eyebox uniformity. A commonly used method for optimizing the uniformity of diffraction waveguides is to modulate the diffraction efficiency of the pupil expansion grating and/or the outcoupling grating in the diffraction waveguide; specifically, the diffraction efficiency of the pupil expansion grating and/or the outcoupling grating is modulated to increase with the increase of the propagation distance of the light beam. Although the light beam will lose energy each time it encounters the pupil expansion grating and/or the outcoupling grating, the diffraction efficiency will increase with the propagation of the light beam. Therefore, the light beam can still remain uniform at different positions along the propagation direction in the diffraction waveguide. A commonly used method for modulating the diffraction efficiency of the grating is to modulate the parameters of the grating, such as the grating depth or the grating duty cycle.

其中，在通过调制光栅占空比调制衍射效率以优化均匀性时，沿着光线传播路径将扩瞳光栅和/或耦出光栅设为不同占空比，在相同光栅深度下调制占空比有一定的调制能力。然而对于如图1所示的一维光栅架构的衍射光波导100，包括耦入结构101、扩瞳结构102、耦出结构103以及波导基底104，其中，耦入结构101、扩瞳结构102、耦出结构103均实现为一维光栅。结合图2，可以看到在其他参数不变仅调制占空比的情况下，一维光栅在占空比FF＝50％左右时能达到衍射效率上限，此占空比也是工艺较易实现的；如若需要衍射效率下限达到较低值如0.5％左右，则需要将占空比设为15％或90％这种非常极限的数值，此占空比在工艺实现上难度较大。参考图3(a)，一维光栅的占空比FF为光栅单元宽度W占光栅周期T的占比。Among them, when the diffraction efficiency is modulated by modulating the grating duty cycle to optimize the uniformity, the pupil expansion grating and/or the coupling-out grating are set to different duty cycles along the light propagation path, and the duty cycle modulation has a certain modulation capability at the same grating depth. However, for the diffraction optical waveguide 100 of the one-dimensional grating architecture as shown in FIG1, it includes a coupling-in structure 101, a pupil expansion structure 102, a coupling-out structure 103 and a waveguide substrate 104, wherein the coupling-in structure 101, the pupil expansion structure 102, and the coupling-out structure 103 are all implemented as a one-dimensional grating. Combined with FIG2, it can be seen that when other parameters remain unchanged and only the duty cycle is modulated, the one-dimensional grating can reach the upper limit of the diffraction efficiency when the duty cycle FF=50%, and this duty cycle is also easier to achieve in the process; if the lower limit of the diffraction efficiency needs to reach a lower value such as about 0.5%, the duty cycle needs to be set to a very extreme value such as 15% or 90%, and this duty cycle is difficult to achieve in the process. Referring to FIG. 3( a ), the duty cycle FF of a one-dimensional grating is the ratio of the grating unit width W to the grating period T.

为解决该问题，本申请提出一种二维光栅结构，由于二维光栅结构具有至少两个方向上的光栅占空比，相较于只有一个占空比的一维光栅结构，在通过占空比调制优化均匀性上具有更大的解空间，而从更大的解空间中更容易找到在工艺较易实现的结构来降低工艺难度的问题。To solve this problem, the present application proposes a two-dimensional grating structure. Since the two-dimensional grating structure has a grating duty cycle in at least two directions, compared to a one-dimensional grating structure with only one duty cycle, it has a larger solution space for optimizing uniformity through duty cycle modulation. From the larger solution space, it is easier to find a structure that is easier to implement in the process to reduce the difficulty of the process.

示例性的，参考图4，该图以二维正交光栅为例，示出了二维光栅结构的衍射效率与占空比的关系示意图，图4中横坐标为X方向占空比(FF_x)，纵坐标为1级衍射效率，不同的曲线分别对应不同的Y方向占空比(FF_y)。比如，黑色实线代表Y方向占空比固定为80％时，1级衍射效率随X方向占空比变化的曲线。从该图中可以看出如若需要衍射效率下限达到较低值如0.5％左右，有多个解，且工艺都较易实现，比如：FF_x＝50％，FF_y＝60％。参考图3(B)，二维正交光栅的X方向占空比(FF_x)为光栅单元X方向宽度Wx占X方向光栅周期Tx的占比，Y方向占空比(FF_y)为光栅单元Y方向宽度Wy占Y方向光栅周期Ty的占比。Exemplarily, refer to FIG. 4, which takes a two-dimensional orthogonal grating as an example, and shows a schematic diagram of the relationship between the diffraction efficiency and the duty cycle of a two-dimensional grating structure. In FIG. 4, the horizontal axis is the X-direction duty cycle (FF_x), and the vertical axis is the first-order diffraction efficiency. Different curves correspond to different Y-direction duty cycles (FF_y). For example, the black solid line represents the curve of the first-order diffraction efficiency changing with the X-direction duty cycle when the Y-direction duty cycle is fixed at 80%. It can be seen from the figure that if the lower limit of the diffraction efficiency needs to reach a lower value such as about 0.5%, there are multiple solutions, and the process is relatively easy to implement, such as: FF_x = 50%, FF_y = 60%. Referring to FIG. 3 (B), the X-direction duty cycle (FF_x) of the two-dimensional orthogonal grating is the proportion of the X-direction width Wx of the grating unit to the X-direction grating period Tx, and the Y-direction duty cycle (FF_y) is the proportion of the Y-direction width Wy of the grating unit to the Y-direction grating period Ty.

有鉴于此，本发明提供一种二维光栅结构，用于衍射光波导的扩瞳结构和/或耦出结构，二维光栅结构包括：至少在两个方向上周期性排布的多个光栅单元，其中，在至少两个方向上周期性排布的多个光栅单元被配置为：使得光束在衍射光波导中的传播路径仅被多个光栅单元在其中一个方向上形成的周期性结构影响。也就是说，这种新型的二维光栅结构虽然在结构上是二维的，但仅存在一个方向上的衍射级次。In view of this, the present invention provides a two-dimensional grating structure for pupil expansion of a diffractive optical waveguide. The two-dimensional grating structure comprises: a plurality of grating units arranged periodically in at least two directions, wherein the plurality of grating units arranged periodically in at least two directions are configured so that the propagation path of the light beam in the diffraction light waveguide is only affected by the periodic structure formed by the plurality of grating units in one direction. In other words, although this novel two-dimensional grating structure is two-dimensional in structure, it only has diffraction orders in one direction.

为了方便描述，二维光栅结构包括至少在两个方向上周期性排布的多个光栅单元，定义这至少两个方向中影响光束传播路径的周期性结构的方向为目标方向，除该目标方向外的方向为其他方向。可以理解，如图1所示的衍射光波导架构中选用二维光栅用作扩瞳光栅和/或耦出光栅之后，相较于采用一维光栅(周期性结构的方向为目标方向)用作扩瞳光栅和/或耦出光栅而言，可能会对衍射光波导中原有的光束传播路径产生影响，进而可能增大衍射光波导均匀性的优化复杂度。因此，本申请提出通过对光栅周期进行优化，将二维光栅的其中一个方向的光栅周期配置为：该光栅周期下的光栅结构能够在K域上起作用，以用于控制光束在波导基底内的传播路径，同时其他方向上的光栅周期被配置，使得该光栅周期下的光栅结构在K域上不起作用，即：不会影响原有的光束传播路径。For the convenience of description, the two-dimensional grating structure includes a plurality of grating units arranged periodically in at least two directions, and the direction of the periodic structure affecting the light beam propagation path in the at least two directions is defined as the target direction, and the directions other than the target direction are other directions. It can be understood that after the two-dimensional grating is selected as the pupil expansion grating and/or the outcoupling grating in the diffraction light waveguide architecture shown in FIG1, compared with the use of a one-dimensional grating (the direction of the periodic structure is the target direction) as the pupil expansion grating and/or the outcoupling grating, it may affect the original light beam propagation path in the diffraction light waveguide, thereby increasing the optimization complexity of the uniformity of the diffraction light waveguide. Therefore, the present application proposes to optimize the grating period, and configure the grating period of one direction of the two-dimensional grating as follows: the grating structure under the grating period can function in the K domain to control the propagation path of the light beam in the waveguide substrate, and the grating period in other directions is configured so that the grating structure under the grating period does not function in the K domain, that is, it will not affect the original light beam propagation path.

可见，本发明提供的技术方案，可以在选用二维光栅优化占空比选择自由度的同时，使得二维光栅其中一个方向上的光栅周期结构对衍射光波导中的光束传播路径不产生影响，而不加大均匀性调节的复杂度。It can be seen that the technical solution provided by the present invention can optimize the duty cycle selection freedom by selecting a two-dimensional grating, while ensuring that the grating periodic structure in one direction of the two-dimensional grating has no effect on the light beam propagation path in the diffraction waveguide without increasing the complexity of uniformity adjustment.

下面以具体地实施例对本发明的技术方案进行详细说明。The technical solution of the present invention is described in detail below with specific embodiments.

根据本发明的一实施例，提供了一种二维光栅结构，用于衍射光波导的扩瞳结构和/或耦出结构，二维光栅结构包括：至少在两个方向上周期性排布的多个光栅单元，其中，在至少两个方向上周期性排布的多个光栅单元被配置为：使得光束在衍射光波导中的传播路径仅被多个光栅单元在其中一个方向上形成的周期性结构影响。According to one embodiment of the present invention, a two-dimensional grating structure is provided for a pupil expansion structure and/or a coupling-out structure of a diffraction optical waveguide, wherein the two-dimensional grating structure comprises: a plurality of grating units arranged periodically in at least two directions, wherein the plurality of grating units arranged periodically in at least two directions are configured such that a propagation path of a light beam in the diffraction optical waveguide is only affected by a periodic structure formed by the plurality of grating units in one direction.

其中，光栅单元的形状可以为圆形、椭圆形、矩形或多边形；当然也可以是其他实现形式，任何可以实现本申请技术效果的光栅单元形状的实现形式均在本发明的保护范围内，本申请并不以此为限。此外，二维光栅结构不同位置的光栅单元的形状也可以相同或者不同。The shape of the grating unit can be circular, elliptical, rectangular or polygonal; of course, it can also be other implementation forms. Any implementation form of the grating unit shape that can achieve the technical effect of the present application is within the protection scope of the present invention, and the present application is not limited thereto. In addition, the shapes of the grating units at different positions of the two-dimensional grating structure can also be the same or different.

一种实施例中，其中一个方向为目标方向，至少两个方向中除目标方向外的方向为其他方向，多个光栅单元在目标方向上形成的周期性结构被配置为：目标方向上形成的周期性结构的周期适配于光束的波长以及衍射光波导的波导基底的折射率，以使得光束在衍射光波导中的传播路径被目标方向上形成的周期性结构影响；多个光栅单元在其它方向上形成的周期性结构被配置为：其它方向上形成的周期性结构的周期适配于光束的波长以及衍射光波导的波导基底的折射率，以使得光束在衍射光波导中的传播路径不被其它方向上形成的周期性结构影响。In one embodiment, one direction is a target direction, and directions other than the target direction in at least two directions are other directions, and the periodic structure formed by the multiple grating units in the target direction is configured as follows: the period of the periodic structure formed in the target direction is adapted to the wavelength of the light beam and the refractive index of the waveguide substrate of the diffraction optical waveguide, so that the propagation path of the light beam in the diffraction optical waveguide is affected by the periodic structure formed in the target direction; and the periodic structure formed by the multiple grating units in other directions is configured as follows: the period of the periodic structure formed in other directions is adapted to the wavelength of the light beam and the refractive index of the waveguide substrate of the diffraction optical waveguide, so that the propagation path of the light beam in the diffraction optical waveguide is not affected by the periodic structure formed in other directions.

其中，任一光栅单元均在上述至少在两个方向的任一方向上周期性排布。也就是任一光栅单元具有至少两种周期性。 Wherein, any grating unit is periodically arranged in any direction of at least two directions, that is, any grating unit has at least two periodicities.

下面具体介绍对多个光栅单元在其它方向上形成的周期性结构具体配置要求：为了说明方便引入主光栅和辅助光栅的概念，主光栅指的是：二维光栅结构中的沿目标方向周期性排列的光栅结构。辅助光栅结构指的是：二维光栅结构中的沿其他方向周期性排列的光栅结构。其中，主光栅只有一个，辅助光栅可以有多个。参考图5，二维光栅结构包括主光栅G1和辅助光栅G2。The following specifically introduces the specific configuration requirements for the periodic structure formed by multiple grating units in other directions: For the convenience of explanation, the concepts of main grating and auxiliary grating are introduced. The main grating refers to: a grating structure that is periodically arranged along the target direction in a two-dimensional grating structure. The auxiliary grating structure refers to: a grating structure that is periodically arranged along other directions in a two-dimensional grating structure. Among them, there is only one main grating, and there can be multiple auxiliary gratings. Referring to Figure 5, the two-dimensional grating structure includes a main grating G1 and an auxiliary grating G2.

如图6所示，K域图中，假设光束初始耦入波导的K矢量坐标为(K_x0，K_y0)；光栅的光栅周期为d，光栅的光栅矢量与X轴夹角为θ，则经光栅衍射后K矢量坐标为 As shown in FIG6 , in the K domain diagram, assuming that the K vector coordinates of the light beam initially coupled into the waveguide are (K _x0 , _Ky0 ); the grating period of the grating is d, and the angle between the grating vector of the grating and the X-axis is θ, then the K vector coordinates after the grating diffraction are

其中，m为衍射级次，优选地，m＝±1。Wherein, m is the diffraction order, preferably, m=±1.

在二维光栅结构用于衍射光波导的扩瞳结构时，光束经扩瞳结构的主光栅(即二维光栅结构的主光栅)衍射后，K矢量坐标须满足以下关系：
When a two-dimensional grating structure is used for a pupil expansion structure of a diffractive optical waveguide, after the light beam is diffracted by the main grating of the pupil expansion structure (i.e., the main grating of the two-dimensional grating structure), the K vector coordinate must satisfy the following relationship:

光束经扩瞳结构的任一辅助光栅衍射(即二维光栅结构的任一辅助光栅)后，K矢量坐标须满足以下关系：
After the light beam is diffracted by any auxiliary grating of the pupil expansion structure (i.e., any auxiliary grating of the two-dimensional grating structure), the K vector coordinate must satisfy the following relationship:

其中，n为波导基底的折射率，λ为光束波长，d_i为第i个辅助光栅的周期。Where n is the refractive index of the waveguide substrate, λ is the wavelength of the light beam, and d _i is the period of the i-th auxiliary grating.

需要说明的是，K域图中内圈代表波导基底的全反射条件，外圈代表波导基底材料所可以达到得最大K值，通常，耦入结构将光束的K值平移到环形区域，即使得光束满足在波导基底内全反射传播的条件而耦入波导基底；扩展结构将部分光束的K值在环形区域内平移，即使得光束得到扩展，若向多个方向扩展即有多个光束传播路径；耦出结构将部分光束的K值从环形区域平移到内圈区域，即使得光束耦出到人眼。It should be noted that the inner circle in the K-domain diagram represents the total reflection condition of the waveguide substrate, and the outer circle represents the maximum K value that the waveguide substrate material can achieve. Usually, the coupling-in structure translates the K value of the light beam to the annular area, so that the light beam satisfies the condition of total reflection propagation in the waveguide substrate and is coupled into the waveguide substrate; the expansion structure translates the K value of part of the light beam in the annular area, so that the light beam is expanded. If it is expanded in multiple directions, there are multiple light beam propagation paths; the coupling-out structure translates the K value of part of the light beam from the annular area to the inner circle area, so that the light beam is coupled out to the human eye.

在本申请中，由于扩瞳结构的主光栅是用来控制光束传播路径的光栅，扩瞳结构的辅助光栅不影响光束传播路径，那么经扩瞳结构的主光栅作用后得到的K矢量坐标需位于K域图中环形区域内，即满足公式(1)，经扩瞳结构的辅助光栅作用后得到的K矢量坐标需位于K域图中外圈外，即满足公式(2)，这样，经扩瞳结构的主光栅衍射后的光束能保持在波导中继续全反射传输，经扩瞳结构的辅助光栅衍射后的光束才不会产生另外的光束传播路径，也不会耦出波导基底产生漏光。继续参考图6(a)，光束经扩瞳结构的主光栅K_epe1作用后矢量坐标位于K域图中环形区域内，继续在波导基底内传输，经扩瞳结构的主光栅K_epe2作用后矢量坐标位于K域图中外圈外，不再存在。In the present application, since the main grating of the pupil expansion structure is a grating used to control the propagation path of the light beam, and the auxiliary grating of the pupil expansion structure does not affect the propagation path of the light beam, the K vector coordinates obtained after the main grating of the pupil expansion structure acts on it must be located in the annular area in the K domain diagram, that is, satisfying formula (1), and the K vector coordinates obtained after the auxiliary grating of the pupil expansion structure acts on it must be located outside the outer circle in the K domain diagram, that is, satisfying formula (2). In this way, the light beam diffracted by the main grating of the pupil expansion structure can remain in the waveguide and continue to be transmitted by total reflection, and the light beam diffracted by the auxiliary grating of the pupil expansion structure will not generate another light beam propagation path, nor will it be coupled out of the waveguide substrate to generate light leakage. Continuing to refer to Figure 6 (a), after the main grating _Kepe1 of the pupil expansion structure acts on the light beam, the vector coordinates are located in the annular area in the K domain diagram, and continue to be transmitted in the waveguide substrate. After the main grating _Kepe2 of the pupil expansion structure acts on it, the vector coordinates are located outside the outer circle in the K domain diagram and no longer exist.

在二维光栅结构用于衍射光波导的耦出结构时，光束经耦出结构的主光栅(即二维光栅结构的主光栅)衍射后，K矢量坐标须满足以下关系：
When a two-dimensional grating structure is used for the outcoupling structure of a diffractive optical waveguide, after the light beam is diffracted by the main grating of the outcoupling structure (i.e., the main grating of the two-dimensional grating structure), the K vector coordinate must satisfy the following relationship:

光束经耦出结构的任一辅助光栅(即二维光栅结构的任一辅助光栅)衍射后，K矢量坐标也须满足上述式(2)。After the light beam is diffracted by any auxiliary grating of the outcoupling structure (ie, any auxiliary grating of the two-dimensional grating structure), the K vector coordinate must also satisfy the above formula (2).

在本申请中，由于耦出结构的主光栅是用来控制光束传播路径以及光束耦出的光栅，耦出结构的辅助光栅不影响光束传播路径也无需导致光耦出，那么经耦出结构的主光栅作用后得到的K矢量坐标需位于K域图中内圈内，即满足公式(3)，经耦出结构的辅助光栅作用后得到的K矢量坐标需位于K域图中外圈外，即满足公式(2)，这样经耦出结构的主光栅衍射后产生光束耦出，经耦出结构的辅助光栅衍射后的部分光束也不会产生另外的光束传播路径，也不会耦出波导基底。继续参考图6(b)，光束经耦出结构的主光栅K_out1作用后矢量坐标位于K域图中内圈内，耦出波导基底，经扩瞳结构的主光栅K_out2作用后矢量坐标位于K域图中外圈外，不再存在。In the present application, since the main grating of the outcoupling structure is a grating used to control the beam propagation path and the outcoupling of the beam, the auxiliary grating of the outcoupling structure does not affect the beam propagation path and does not need to cause light outcoupling, then the K vector coordinates obtained after the main grating of the outcoupling structure acts on it must be located in the inner circle of the K domain diagram, that is, satisfying formula (3), and the K vector coordinates obtained after the auxiliary grating of the outcoupling structure acts on it must be located outside the outer circle of the K domain diagram, that is, satisfying formula (2), so that after the main grating of the outcoupling structure diffracts, the outcoupling of the beam is generated, and the partial beam diffracted by the auxiliary grating of the outcoupling structure will not generate another beam propagation path, nor will it be coupled out of the waveguide substrate. Continuing to refer to Figure 6 (b), after the main grating K _out1 of the outcoupling structure acts on the beam, the vector coordinates are located in the inner circle of the K domain diagram, and the waveguide substrate is coupled out, and after the main grating K _out2 of the pupil expansion structure acts on it, the vector coordinates are located outside the outer circle of the K domain diagram and no longer exist.

为了方便工艺制作，优选地，多个光栅单元在第i个方向上形成的周期性结构的周期被配置为可选范围内的最大值，可选范围表征了光束在衍射光波导中的传播路径仅被多个光栅单元在其中一个方向上形成的周期性结构影响时，多个光栅单元在第i个方向上形成的周期性结构的周期的取值。In order to facilitate the process manufacturing, preferably, the period of the periodic structure formed by the multiple grating units in the i-th direction is configured as a maximum value within an optional range, and the optional range represents the value of the period of the periodic structure formed by the multiple grating units in the i-th direction when the propagation path of the light beam in the diffraction optical waveguide is only affected by the periodic structure formed by the multiple grating units in one direction.

一种具体的举例中，多个光栅单元在其中一个方向上形成的周期性结构与其他方向形成的周期性结构之间的夹角为45°；另一种具体的举例中，多个光栅单元在其中一个方向上形成的周期性结构与其他方向形成的周期性结构之间的夹角为60°；当然也可以是其他实现形式，任何可以实现本申请技术效果的主光栅与辅助光栅之间的夹角的实现形式均在本发明的保护范围内，本申请并不以此为限。In a specific example, the angle between the periodic structure formed by the multiple grating units in one direction and the periodic structure formed in other directions is 45°; in another specific example, the angle between the periodic structure formed by the multiple grating units in one direction and the periodic structure formed in other directions is 60°; of course, other implementation forms are also possible. Any implementation form of the angle between the main grating and the auxiliary grating that can achieve the technical effect of the present application is within the protection scope of the present invention, and the present application is not limited to this.

以上，是对于衍射光波导中，扩瞳结构和/或耦出结构中的一维光栅结构替换为二维光栅结构后仍保持原有光束传播路径不变的实现方式的说明。The above is an explanation of an implementation method for maintaining the original light beam propagation path unchanged after the one-dimensional grating structure in the pupil expansion structure and/or the outcoupling structure in the diffractive light waveguide is replaced with a two-dimensional grating structure.

一种实施例中，多个光栅单元在其它方向上形成的周期性结构还被配置为：使得光束在衍射光波导中的衍射效率被多个光栅单元在其他方向上形成的周期性结构共同影响。也就是说，对于衍射光波导中扩瞳结构和/或耦出结构中的一维光栅结构替换为二维光栅结构后，光栅衍射效率发生了变化。In one embodiment, the periodic structures formed by the multiple grating units in other directions are further configured so that the diffraction efficiency of the light beam in the diffraction waveguide is jointly affected by the periodic structures formed by the multiple grating units in other directions. That is, after the one-dimensional grating structure in the pupil expansion structure and/or the outcoupling structure in the diffraction waveguide is replaced with a two-dimensional grating structure, the grating diffraction efficiency changes.

一种实施例中，二维光栅结构的不同位置的光栅占空比不同，以调节光束在二维光栅结构作用下扩瞳或者耦出的均匀性。In one embodiment, the grating duty cycles at different positions of the two-dimensional grating structure are different to adjust the uniformity of pupil expansion or outcoupling of the light beam under the action of the two-dimensional grating structure.

一种实施方式中，二维光栅结构被配置为：通过配置二维光栅结构的不同区域的光栅占空比，以使得在衍射光波导中，沿光束传播的方向，二维光栅结构的衍射效率逐渐增大，以调节光束在二维光栅结构作用下扩瞳或者耦出的均匀性。In one embodiment, the two-dimensional grating structure is configured as follows: by configuring the grating duty ratio of different regions of the two-dimensional grating structure, the diffraction efficiency of the two-dimensional grating structure gradually increases along the direction of light beam propagation in the diffraction waveguide, so as to adjust the uniformity of pupil expansion or outcoupling of the light beam under the action of the two-dimensional grating structure.

一种实施例中，还可以同时调制二维光栅结构的光栅深度，以使得在衍射光波导中，沿光束传播的方向，二维光栅结构的衍射效率逐渐增大。In one embodiment, the grating depth of the two-dimensional grating structure may also be modulated simultaneously, so that in the diffraction optical waveguide, along the direction of light beam propagation, the diffraction efficiency of the two-dimensional grating structure gradually increases.

一种实施方式中，二维光栅结构被配置为：通过配置二维光栅结构的不同区域的光栅占空比，以使得在衍射光波导中，沿光束传播的方向，二维光栅结构的衍射效率逐渐增大。此时，可以看作将二维光栅结构划分为多个区域，每个区域内光栅占空比一致。在此基础上，还可以进一步调制二维光栅结构的光栅深度，使得每个区域内沿光束传播的方向衍射效率逐渐增大，同时整个二维光栅结构内沿光束传播的方向衍射效率也是逐渐增大。In one embodiment, the two-dimensional grating structure is configured as follows: by configuring the grating duty ratios of different regions of the two-dimensional grating structure, the two-dimensional light is The diffraction efficiency of the grating structure gradually increases. At this point, it can be regarded as dividing the two-dimensional grating structure into multiple regions, and the grating duty cycle in each region is consistent. On this basis, the grating depth of the two-dimensional grating structure can be further modulated so that the diffraction efficiency in each region along the direction of light beam propagation gradually increases, and at the same time, the diffraction efficiency in the entire two-dimensional grating structure along the direction of light beam propagation also gradually increases.

其他实施方式中，二维光栅结构的衍射效率也可以呈现其他变化趋势，只要可以调节光束在二维光栅结构作用下扩瞳或者耦出的均匀性的衍射效率变化趋势的实现形式，均在本发明的保护范围内，本发明并不以此为限。In other embodiments, the diffraction efficiency of the two-dimensional grating structure may also show other change trends. As long as the implementation form of the diffraction efficiency change trend can adjust the uniformity of pupil expansion or coupling of the light beam under the action of the two-dimensional grating structure, it is within the protection scope of the present invention, and the present invention is not limited to this.

另一方面，本发明还提供了一种扩瞳结构，包括本发明前述实施例的二维光栅结构。On the other hand, the present invention further provides a pupil expansion structure, comprising the two-dimensional grating structure of the aforementioned embodiment of the present invention.

示例性的，多个光栅单元在其中一个方向上形成的周期性结构与多个光栅单元在其它方向上形成的周期性结构之间形成的夹角的取值为45°。也即主光栅与辅助光栅的夹角为45°。当然也可以是其他角度，比如60°。这里的60°、45°仅是示意性说明，本发明对该夹角取值不作限定，该角度的取值范围为大于0°且小于180°。Exemplarily, the angle formed by the periodic structure formed by the multiple grating units in one direction and the periodic structure formed by the multiple grating units in other directions is 45°. That is, the angle between the main grating and the auxiliary grating is 45°. Of course, it can also be other angles, such as 60°. The 60° and 45° here are only schematic illustrations, and the present invention does not limit the value of the angle, and the value range of the angle is greater than 0° and less than 180°.

一种实施例中，扩瞳结构中沿着光束传播的方向衍射效率依次增大。In one embodiment, the diffraction efficiency in the pupil expansion structure increases successively along the direction of light beam propagation.

具体地，沿着光束传播的方向，调制二维光栅结构的占空比，使得扩瞳结构中沿着光束传播的方向衍射效率依次增大，以优化扩瞳均匀性。Specifically, along the direction of light beam propagation, the duty cycle of the two-dimensional grating structure is modulated so that the diffraction efficiency in the pupil expansion structure along the direction of light beam propagation increases successively to optimize pupil expansion uniformity.

在另外的实施例中，沿着光束传播的方向还可以同时调制二维光栅结构的光栅深度，使得扩瞳结构中沿着光束传播的方向衍射效率逐渐增大。In another embodiment, the grating depth of the two-dimensional grating structure can also be modulated simultaneously along the direction of light beam propagation, so that the diffraction efficiency of the pupil expansion structure along the direction of light beam propagation gradually increases.

一种实施例中，扩瞳结构还包括一维光栅结构，且扩瞳结构中沿着光束传播的方向转折效率依次增大。In one embodiment, the pupil expansion structure further includes a one-dimensional grating structure, and the turning efficiency in the pupil expansion structure increases successively along the direction of light beam propagation.

需要说明的是，继续参考图3与图4，可以看出，一维光栅结构相较于二维光栅结构能得到更高的衍射效率，而且一维光栅结构获得高衍射效率时的占空比也是工艺上容易实现的结构，可见，一维光栅结构在调制占空比实现高衍射效率时有优势，二维光栅结构在调制占空比实现较低衍射效率时有优势。这样，扩瞳结构中需要高衍射效率的位置还可以采用一维光栅结构。参考图7，衍射光波导200包括耦入结构201、扩瞳结构202、耦出结构203和波导基底204，其中，扩瞳结构202的不同区域为占空比不同的二维光栅结构10或一维光栅结构20，光束传播较近的区域不需要高的衍射效率，可选用二维光栅结构10，光束传播较远的区域需要相对较高的衍射效率，可选用一维光栅结构20。需要说明的是，图7中对于扩瞳结构的分区设置仅为示意，还可以有更多的不同占空比的二维光栅结构或者一维光栅结构。It should be noted that, referring to FIG. 3 and FIG. 4 , it can be seen that the one-dimensional grating structure can obtain a higher diffraction efficiency than the two-dimensional grating structure, and the duty cycle of the one-dimensional grating structure when obtaining high diffraction efficiency is also a structure that is easy to implement in terms of technology. It can be seen that the one-dimensional grating structure has an advantage when the duty cycle is modulated to achieve high diffraction efficiency, and the two-dimensional grating structure has an advantage when the duty cycle is modulated to achieve lower diffraction efficiency. In this way, the position where high diffraction efficiency is required in the pupil expansion structure can also adopt a one-dimensional grating structure. Referring to FIG. 7 , the diffraction optical waveguide 200 includes a coupling-in structure 201, a pupil expansion structure 202, a coupling-out structure 203 and a waveguide substrate 204, wherein different regions of the pupil expansion structure 202 are two-dimensional grating structures 10 or one-dimensional grating structures 20 with different duty cycles, and the region where the light beam propagates closer does not require high diffraction efficiency, and the two-dimensional grating structure 10 can be selected, and the region where the light beam propagates farther requires relatively high diffraction efficiency, and the one-dimensional grating structure 20 can be selected. It should be noted that the partition arrangement of the pupil expansion structure in FIG. 7 is only for illustration, and there may be more two-dimensional grating structures or one-dimensional grating structures with different duty cycles.

当然，在其他的实施例中，扩瞳结构中二维光栅结构与一维光栅结构也可交替排布。可以理解，在设计扩瞳结构中具体的光栅结构时，是以转折效率为标的进行设计的，设计使得扩瞳结构中沿着光束传播的方向转折效率依次增大，从而提高光束扩展均匀性。那么对于扩瞳结构中的任意位置或区域，针对该区域所需要的转折效率，能达到该转折效率且工艺上占空比较易实现的光栅结构(不论二维光栅结构或者一维光栅结构)都可以成为解。Of course, in other embodiments, the two-dimensional grating structure and the one-dimensional grating structure in the pupil expansion structure may also be arranged alternately. It can be understood that when designing the specific grating structure in the pupil expansion structure, the design is based on the turning efficiency, and the design makes the turning efficiency in the pupil expansion structure along the direction of light beam propagation increase successively, thereby improving the uniformity of light beam expansion. Then, for any position or area in the pupil expansion structure, for the turning efficiency required for the area, a grating structure (whether a two-dimensional grating structure or a one-dimensional grating structure) that can achieve the turning efficiency and is easier to realize in terms of process can be a solution.

再一方面，本发明还提供了一种耦出结构，包括本发明前述实施例的二维光栅结构。On the other hand, the present invention also provides a coupling-out structure, comprising the two aforementioned embodiments of the present invention. dimensional grating structure.

示例性地，多个光栅单元在其中一个方向上形成的周期性结构与多个光栅单元在其它方向上形成的周期性结构之间形成的角度的取值为90°。即主光栅与辅助光栅的夹角为90°。当然，也可以是其他角度，比如60°。这里的60°或者90°仅是示意性说明，本发明对该夹角取值不作限定，该角度的取值范围为大于0°且小于180°。Exemplarily, the angle formed by the periodic structure formed by the multiple grating units in one direction and the periodic structure formed by the multiple grating units in other directions is 90°. That is, the angle between the main grating and the auxiliary grating is 90°. Of course, it can also be other angles, such as 60°. The 60° or 90° here is only a schematic illustration, and the present invention does not limit the value of the angle, and the value range of the angle is greater than 0° and less than 180°.

一种实施例中，耦出结构中沿着光束传播的方向衍射效率依次增大。In one embodiment, the diffraction efficiency in the out-coupling structure increases successively along the direction of light beam propagation.

具体地，沿着光束传播的方向，调制二维光栅结构的占空比，使得耦出结构中沿着光束传播的方向衍射效率依次增大，以优化扩瞳及耦出均匀性。Specifically, along the direction of light beam propagation, the duty cycle of the two-dimensional grating structure is modulated so that the diffraction efficiency in the outcoupling structure along the direction of light beam propagation increases successively, so as to optimize pupil expansion and outcoupling uniformity.

在另外的实施例中，沿着光束传播的方向还可以同时调制二维光栅结构的光栅深度，使得耦出结构中沿着光束传播的方向衍射效率逐渐增大。In another embodiment, the grating depth of the two-dimensional grating structure can also be modulated simultaneously along the direction of light beam propagation, so that the diffraction efficiency of the outcoupling structure along the direction of light beam propagation gradually increases.

一种实施例中，耦出结构还包括一维光栅结构，且耦出结构中沿着光束传播的方向衍射效率依次增大。In one embodiment, the out-coupling structure further includes a one-dimensional grating structure, and the diffraction efficiency in the out-coupling structure increases successively along the direction of light beam propagation.

与扩瞳结构类似，耦出结构中需要高衍射效率的位置也可以采用一维光栅结构。继续参考图7，耦出结构203的不同区域为占空比不同的二维光栅结构10或一维光栅结构20，光束传播较近的区域不需要高的衍射效率，可选用二维光栅结构10，光束传播较远的区域需要相对较高的衍射效率，可选用一维光栅结构20。需要说明的是，图7中对于耦出结构的分区设置仅为示意，还可以有更多的不同占空比的二维光栅结构或者一维光栅结构。Similar to the pupil expansion structure, a one-dimensional grating structure can also be used in the position where high diffraction efficiency is required in the out-coupling structure. Continuing to refer to FIG7, different regions of the out-coupling structure 203 are two-dimensional grating structures 10 or one-dimensional grating structures 20 with different duty cycles. The region where the light beam propagates closer does not require high diffraction efficiency, and the two-dimensional grating structure 10 can be selected. The region where the light beam propagates farther requires relatively high diffraction efficiency, and the one-dimensional grating structure 20 can be selected. It should be noted that the partition setting of the out-coupling structure in FIG7 is only for illustration, and there can be more two-dimensional grating structures or one-dimensional grating structures with different duty cycles.

当然，在其他的实施例中，耦出结构中二维光栅结构与一维光栅结构也可交替排布。可以理解，在设计耦出结构中具体的光栅结构时，是以耦出效率为标的进行设计的，设计使得耦出结构中沿着光束传播的方向耦出效率依次增大，从而提高光束扩展均匀性。那么对于耦出结构中的任意位置或区域，针对该区域所需要的耦出效率，能达到该耦出效率且工艺上占空比较易实现的光栅结构(不论二维光栅结构或者一维光栅结构)都可以成为解。Of course, in other embodiments, the two-dimensional grating structure and the one-dimensional grating structure in the outcoupling structure may also be arranged alternately. It can be understood that when designing a specific grating structure in the outcoupling structure, the outcoupling efficiency is taken as the target for design, and the outcoupling efficiency along the direction of light beam propagation in the outcoupling structure is designed to increase successively, thereby improving the uniformity of light beam expansion. Then, for any position or region in the outcoupling structure, for the outcoupling efficiency required for the region, a grating structure (whether a two-dimensional grating structure or a one-dimensional grating structure) that can achieve the outcoupling efficiency and is relatively easy to realize in terms of process can be a solution.

还一方面，本发明还提供了一种衍射光波导200，包括波导基底204、耦入结构201、扩瞳结构202以及耦出结构203，扩瞳结构202和/或耦出结构203包括本发明前述实施例的二维光栅结构10。On the other hand, the present invention also provides a diffraction optical waveguide 200, including a waveguide substrate 204, a coupling-in structure 201, a pupil expansion structure 202 and a coupling-out structure 203, wherein the pupil expansion structure 202 and/or the coupling-out structure 203 include the two-dimensional grating structure 10 of the aforementioned embodiment of the present invention.

进一步地，扩瞳结构202和/或耦出结构203还包括一维光栅结构20。Furthermore, the pupil expansion structure 202 and/or the outcoupling structure 203 further includes a one-dimensional grating structure 20 .

一种实施例中，扩瞳结构和耦出结构的光栅结构深度相同。In one embodiment, the grating structures of the pupil expansion structure and the outcoupling structure have the same depth.

一种实施例中，扩瞳结构和/或耦出结构中光栅结构的光栅深度一致；可实施地，扩瞳结构中光栅结构的光栅深度一致；可实施地，耦出结构中光栅结构的光栅深度一致；可实施地，扩瞳结构中光栅结构的光栅深度一致，且耦出结构中光栅结构的光栅深度一致，但两者光栅深度不同。In one embodiment, the grating depth of the grating structure in the pupil expansion structure and/or the out-coupling structure is consistent; optionally, the grating depth of the grating structure in the pupil expansion structure is consistent; optionally, the grating depth of the grating structure in the out-coupling structure is consistent; optionally, the grating depth of the grating structure in the pupil expansion structure is consistent, and the grating depth of the grating structure in the out-coupling structure is consistent, but the grating depths of the two are different.

一种实施例中，扩瞳结构和/或耦出结构中光栅结构的光栅深度沿着光束传播的方向变化。In one embodiment, the grating depth of the grating structure in the pupil expansion structure and/or the outcoupling structure varies along the propagation direction of the light beam.

此外，衍射光波导最常用的另一种架构与光栅布局，包括沿图像光束传播方向上依次布局的耦入结构和耦出结构。此时衍射光波导不再包括单独的扩瞳结构，耦出结构采用常规的二维光栅同时实现二维扩瞳与耦出，这里常规的二维光栅能衍射产生多个方向的光束传播路径。针对该种架构，为了提高均匀性与效率，通常会对耦出结构进行分区后布置一维光栅，比如，在耦出结构的两侧区域采用常规一维光栅，在耦出结构的中间区域采用常规二维光栅。这种情形下也会存在前述的优化自由度受限，工艺难度高的问题。In addition, another commonly used architecture and grating layout of diffractive waveguides includes a coupling-in structure and a coupling-out structure arranged in sequence along the propagation direction of the image beam. In this case, the diffractive waveguide no longer includes a separate pupil expansion structure, and the coupling-out structure uses a conventional two-dimensional grating to simultaneously achieve two-dimensional pupil expansion and coupling-out. A regular two-dimensional grating can diffract to produce beam propagation paths in multiple directions. For this type of architecture, in order to improve uniformity and efficiency, the outcoupling structure is usually partitioned and a one-dimensional grating is arranged. For example, a regular one-dimensional grating is used on both sides of the outcoupling structure, and a regular two-dimensional grating is used in the middle area of the outcoupling structure. In this case, the aforementioned optimization freedom is limited and the process is difficult.

还一方面，本发明还提供了一种衍射光波导，包括波导基底、耦入结构以及耦出结构，其中，耦出结构分为第一耦出结构、第二耦出结构和第三耦出结构，第二耦出结构位于第一耦出结构和第三耦出结构之间，第一耦出结构和第三耦出结构包括二维光栅结构10。On the other hand, the present invention also provides a diffraction optical waveguide, including a waveguide substrate, a coupling-in structure and a coupling-out structure, wherein the coupling-out structure is divided into a first coupling-out structure, a second coupling-out structure and a third coupling-out structure, the second coupling-out structure is located between the first coupling-out structure and the third coupling-out structure, and the first coupling-out structure and the third coupling-out structure include a two-dimensional grating structure 10.

可实施地，第一耦出结构和第三耦出结构还包括一维光栅结构，第一耦出结构和第三耦出结构中二维光栅结构的不同区域的光栅占空比以及一维光栅结构的光栅占空比被调制，以使得在衍射光波导中，沿图像光束传播的方向，第一耦出结构和第三耦出结构的衍射效率逐渐增大。In practice, the first out-coupling structure and the third out-coupling structure also include a one-dimensional grating structure, and the grating duty ratios of different regions of the two-dimensional grating structure in the first out-coupling structure and the third out-coupling structure and the grating duty ratio of the one-dimensional grating structure are modulated so that in the diffraction optical waveguide, along the direction of propagation of the image light beam, the diffraction efficiency of the first out-coupling structure and the third out-coupling structure gradually increases.

其中，基于不同光栅结构在调制占空比实现不同衍射效率时的各自优势，与前述实施例中关于光栅结构类型的设置类似，第一耦出结构和第三耦出结构中需要高衍射效率的位置可以采用一维光栅结构，第一耦出结构和第三耦出结构中需要较低衍射效率的位置可以本发明提供的新型的二维光栅结构。Among them, based on the respective advantages of different grating structures in achieving different diffraction efficiencies when modulating the duty cycle, similar to the setting of the grating structure type in the aforementioned embodiment, the positions in the first out-coupling structure and the third out-coupling structure that require high diffraction efficiency can adopt a one-dimensional grating structure, and the positions in the first out-coupling structure and the third out-coupling structure that require lower diffraction efficiency can use the new two-dimensional grating structure provided by the present invention.

这样，在设置常规一维光栅结构的区域部分或全部替换为本发明前述实施例中提供的二维光栅结构10，光束在衍射光波导中的传播路径仅被其在其中一个方向上形成的周期性结构影响，而其他方向形成的周期性结构不影响光束在二维光栅中的传播方向，这样便不会改变原来的光束传播路径。这使得衍射光波导的耦出结构可以通过增加周期性结构的维度来极大提高通过调制占空比优化均匀性的自由度，而且不会因为周期性结构维度的增加引入新的光束传播路径而加大优化均匀性的复杂度，通过光栅占空比优化自由度的提升还能减小工艺难度和工艺成本。In this way, when the area where the conventional one-dimensional grating structure is set is partially or completely replaced with the two-dimensional grating structure 10 provided in the above-mentioned embodiment of the present invention, the propagation path of the light beam in the diffraction optical waveguide is only affected by the periodic structure formed in one direction, while the periodic structure formed in other directions does not affect the propagation direction of the light beam in the two-dimensional grating, so that the original light beam propagation path will not be changed. This allows the outcoupling structure of the diffraction optical waveguide to greatly improve the degree of freedom of optimizing uniformity by modulating the duty cycle by increasing the dimension of the periodic structure, and will not increase the complexity of optimizing uniformity by introducing a new light beam propagation path due to the increase in the dimension of the periodic structure. The improvement of the degree of freedom of optimizing the grating duty cycle can also reduce the process difficulty and process cost.

可实施地，耦出结构中光栅结构的光栅深度一致。Practically, the grating depths of the grating structures in the outcoupling structure are consistent.

可实施地，耦出结构中光栅结构的光栅深度沿着光束传播的方向变化。In practice, the grating depth of the grating structure in the outcoupling structure varies along the propagation direction of the light beam.

当然，在本发明提供的新型的二维光栅结构以及一维光栅结构共同用于衍射光波导的扩瞳结构和/或耦出结构时，对于不同位置关于设置二维光栅结构还是一维光栅结构的选取，还可以取决于该位置所需求的衍射效率被二维光栅结构或一维光栅结构实现时，该二维光栅结构或一维光栅结构的占空比在制备工艺实现上的难易程度，并不一定局限于需要较高衍射效率的位置采用一维光栅结构，需要较低衍射效率的位置则采用二维光栅结构。Of course, when the novel two-dimensional grating structure and one-dimensional grating structure provided by the present invention are used together for the pupil expansion structure and/or out-coupling structure of the diffraction optical waveguide, the choice of setting the two-dimensional grating structure or the one-dimensional grating structure at different positions may also depend on the difficulty of realizing the duty cycle of the two-dimensional grating structure or the one-dimensional grating structure in the preparation process when the diffraction efficiency required at the position is achieved by the two-dimensional grating structure or the one-dimensional grating structure. It is not necessarily limited to using the one-dimensional grating structure at the position requiring higher diffraction efficiency and using the two-dimensional grating structure at the position requiring lower diffraction efficiency.

请参考图7-11，根据本发明的一实施例，提供了一种衍射光波导，以下提到的二维光栅结构同前述二维光栅结构代表的含义并无区别，因而，前述提供的二维光栅结构的实施例均适用于后述二维光栅结构，该衍射光波导包括：波导基底；设置于波导基底表面或内部的耦入结构、扩瞳结构和耦出结构；耦入结构用于将图像光束耦入波导基底并在波导基底内传输，扩瞳结构用于将图像光束扩展传输至耦出结构，耦出结构用于将波导基底内传输的图像光束从波导基底中衍射耦出；扩瞳结构和/或耦出结构至少包括一二维光栅结构，其中二维光栅结构包括：至少在两个方向上周期性排布的多个光栅单元，其中，在至少两个方向上周期性排布的多个光栅单元被配置，使得图像光束在衍射光波导中的传播路径仅被多个光栅单元在其中一个方向上形成的周期性结构影响。Please refer to Figures 7-11. According to an embodiment of the present invention, a diffraction optical waveguide is provided. The two-dimensional grating structure mentioned below has no difference in meaning from the aforementioned two-dimensional grating structure. Therefore, the embodiments of the two-dimensional grating structure provided above are all applicable to the two-dimensional grating structure described below. The diffraction optical waveguide includes: a waveguide substrate; a coupling-in structure, a pupil expansion structure and a coupling-out structure arranged on the surface or inside of the waveguide substrate; the coupling-in structure is used to couple the image light beam into the waveguide substrate and transmit it in the waveguide substrate, the pupil expansion structure is used to expand the image light beam and transmit it to the coupling-out structure, and the coupling-out structure is used to diffract and couple the image light beam transmitted in the waveguide substrate out from the waveguide substrate; the pupil expansion structure and/or the coupling-out structure at least include a two-dimensional grating Structure, wherein the two-dimensional grating structure includes: a plurality of grating units arranged periodically in at least two directions, wherein the plurality of grating units arranged periodically in at least two directions are configured so that the propagation path of the image light beam in the diffraction light waveguide is only affected by the periodic structure formed by the plurality of grating units in one direction.

其中，一种实施方式中，在衍射光波导中，二维光栅结构形成于扩瞳结构中；另一种实施方式中，在衍射光波导中，二维光栅结构形成于耦出结构中；其他实施方式中，在衍射光波导中，二维光栅结构形成于扩瞳结构和耦出结构中。In one embodiment, in a diffraction optical waveguide, a two-dimensional grating structure is formed in a pupil expansion structure; in another embodiment, in a diffraction optical waveguide, a two-dimensional grating structure is formed in a coupling-out structure; in other embodiments, in a diffraction optical waveguide, a two-dimensional grating structure is formed in both a pupil expansion structure and a coupling-out structure.

可实施地，扩瞳结构和耦出结构包括目标方向不同的二维光栅结构，也就是在扩瞳结构中的目标方向为第一目标方向，在耦出结构中的目标方向为第二目标方向，第一目标方向和第二目标方向表征不同的方向。其中，扩瞳结构中第一目标方向与其他方向的夹角，与耦出结构中第二目标方向与其他方向的夹角可以相同也可以不同，该角度范围均为大于0°且小于180°。In practice, the pupil expansion structure and the coupling-out structure include two-dimensional grating structures with different target directions, that is, the target direction in the pupil expansion structure is a first target direction, and the target direction in the coupling-out structure is a second target direction, and the first target direction and the second target direction represent different directions. Among them, the angle between the first target direction and the other direction in the pupil expansion structure and the angle between the second target direction and the other direction in the coupling-out structure can be the same or different, and the angle range is greater than 0° and less than 180°.

示例性的，参考图8，该图示出的衍射光波导包括设置于波导基底表面的耦入结构510、扩瞳结构520和耦出结构530，扩瞳结构520包括二维光栅结构，该二维光栅结构至少包括主光栅521和辅助光栅522，其中主光栅521和辅助光栅522的夹角为90°，耦出结构530包括二维光栅结构，该二维光栅结构至少包括主光栅531和辅助光栅532，其中主光栅531和辅助光栅532为90°。参考图10，该图示出的衍射光波导包括设置于波导基底表面的耦入结构710、扩瞳结构720和耦出结构730，扩瞳结构720包括二维光栅结构，该二维光栅结构至少包括主光栅721和辅助光栅722，其中主光栅721和辅助光栅722的夹角为45°，耦出结构730包括二维光栅结构，该二维光栅结构至少包括主光栅731和辅助光栅732，其中主光栅731和辅助光栅732为60°。需要说明的是图8和10中的角度值仅为夹角取值的示意，不造成限定。Exemplarily, referring to Figure 8, the diffraction optical waveguide shown in the figure includes a coupling-in structure 510, a pupil expansion structure 520 and a coupling-out structure 530 arranged on the surface of the waveguide substrate, the pupil expansion structure 520 includes a two-dimensional grating structure, and the two-dimensional grating structure at least includes a main grating 521 and an auxiliary grating 522, wherein the angle between the main grating 521 and the auxiliary grating 522 is 90°, and the coupling-out structure 530 includes a two-dimensional grating structure, and the two-dimensional grating structure at least includes a main grating 531 and an auxiliary grating 532, wherein the angle between the main grating 531 and the auxiliary grating 532 is 90°. Referring to Fig. 10, the diffraction optical waveguide shown in the figure includes a coupling-in structure 710, a pupil expansion structure 720 and a coupling-out structure 730 arranged on the surface of the waveguide substrate, the pupil expansion structure 720 includes a two-dimensional grating structure, the two-dimensional grating structure includes at least a main grating 721 and an auxiliary grating 722, wherein the angle between the main grating 721 and the auxiliary grating 722 is 45°, and the coupling-out structure 730 includes a two-dimensional grating structure, the two-dimensional grating structure includes at least a main grating 731 and an auxiliary grating 732, wherein the angle between the main grating 731 and the auxiliary grating 732 is 60°. It should be noted that the angle values in Figs. 8 and 10 are only for illustration of the angle values and do not constitute a limitation.

为了实现主光栅能够在K域上起作用，以用于控制光束在波导基底内的传播路径，同时辅助光栅在K域上不起作用，不影响光束在波导基底内的传播路径，进一步地，可实施地，多个光栅单元在其它方向上形成的周期性结构被配置为：其它方向上形成的周期性结构的周期适配于光束的波长以及衍射光波导的波导基底的折射率，以使得光束在衍射光波导中的传播路径不被其它方向上形成的周期性结构影响；其中，其中一个方向为目标方向，其他方向表征了至少两个方向中除目标方向外的方向。In order to enable the main grating to function in the K domain to control the propagation path of the light beam in the waveguide substrate, while the auxiliary grating does not function in the K domain and does not affect the propagation path of the light beam in the waveguide substrate, further, it is feasible to configure the periodic structure formed by the multiple grating units in other directions as follows: the period of the periodic structure formed in other directions is adapted to the wavelength of the light beam and the refractive index of the waveguide substrate of the diffraction light waveguide, so that the propagation path of the light beam in the diffraction light waveguide is not affected by the periodic structure formed in other directions; wherein one of the directions is a target direction, and the other directions represent directions other than the target direction in at least two directions.

可实施的，多个光栅单元在其它方向中的第i个方向上形成的周期性结构的周期被配置为符合以下公式：
In practice, the period of the periodic structure formed by the plurality of grating units in the i-th direction in other directions is configured to comply with the following formula:

其中，(K_x0，K_y0)为光束被多个光栅单元在第i个方向上形成的周期性结构作用前的K矢量坐标，m为衍射级次，n为波导基底的折射率，λ为光束的波长，d_i为多个光栅单元在第i个方向上形成的周期性结构的周期，θ是多个光栅单元在第i个方向上形成的周期性结构的光栅矢量与矢量坐标系中x轴的夹角， (K_x0+m*(2π/d_i)cosθ，K_y0+m*(2π/d_i)sinθ)为光束被多个光栅单元在第i个方向上形成的周期性结构作用后的K矢量坐标。Wherein, (K _x0 , _Ky0 ) is the K vector coordinate of the light beam before being acted upon by the periodic structure formed by the multiple grating units in the i-th direction, m is the diffraction order, n is the refractive index of the waveguide substrate, λ is the wavelength of the light beam, d _i is the period of the periodic structure formed by the multiple grating units in the i-th direction, θ is the angle between the grating vector of the periodic structure formed by the multiple grating units in the i-th direction and the x-axis in the vector coordinate system, (K _x0 +m*(2π/d _i )cosθ, _Ky0 +m*(2π/d _i )sinθ) are K vector coordinates of the light beam after being acted upon by the periodic structure formed by the multiple grating units in the i-th direction.

一种实施例中，多个光栅单元在第i个方向上形成的周期性结构的周期被配置为可选范围内的最大值，可选范围表征了光束在衍射光波导中的传播路径仅被多个光栅单元在其中一个方向上形成的周期性结构影响时，多个光栅单元在第i个方向上形成的周期性结构的周期的取值。In one embodiment, the period of the periodic structure formed by the multiple grating units in the i-th direction is configured as a maximum value within an optional range, and the optional range represents the value of the period of the periodic structure formed by the multiple grating units in the i-th direction when the propagation path of the light beam in the diffraction optical waveguide is only affected by the periodic structure formed by the multiple grating units in one direction.

示例性的，如图9所示，该图示出了图像光束在图8所示的衍射光波导中传输的K域图。对于光束传播的K域图，光束波矢的矢量坐标位于内圈(半径为n₀*2π/λ，n₀为空气折射率)内时，表征光束在波导基底以外的空气中传播，光波波矢的矢量坐标位于圆环内时，表征光束在波导内全反射传输，光波波矢的矢量坐标位于外圈(半径为n*2π/λ)外时，表征光束不存在。再参考图9，图像光束经耦入结构510作用(光栅矢量Kin5)，矢量坐标平移至圆环内，耦入波导基底内全反射传输，传输至扩瞳结构520后，经扩瞳结构520中主光栅521(光栅矢量Kepe51)作用，矢量坐标平移后仍位于圆环内，继续在波导基底内全反射并偏转传播至耦出结构530；经扩瞳结构520中辅助光栅522(光栅矢量Kepe52)作用，矢量坐标平移至外圈之外，光束不存在。传输至耦出结构530后，经耦出结构530中主光栅531(光栅矢量Kout51)作用，矢量坐标平移至内圈内，耦出波导基底；经耦出结构530中辅助光栅532(光栅矢量Kout52)作用，矢量坐标平移至外圈之外，光束不存在。Exemplarily, as shown in Fig. 9, the figure shows the K-domain diagram of the image beam propagating in the diffraction optical waveguide shown in Fig. 8. For the K-domain diagram of beam propagation, when the vector coordinates of the beam wave vector are located in the inner circle (radius is _n0 *2π/λ, _n0 is the refractive index of air), it indicates that the beam propagates in the air outside the waveguide substrate, when the vector coordinates of the light wave vector are located in the ring, it indicates that the beam is totally reflected and transmitted in the waveguide, and when the vector coordinates of the light wave vector are located outside the outer circle (radius is n*2π/λ), it indicates that the beam does not exist. Referring to FIG. 9 again, the image light beam is acted upon by the coupling-in structure 510 (grating vector Kin5), and the vector coordinates are translated into the ring, coupled into the waveguide substrate for total reflection transmission, and after being transmitted to the pupil expansion structure 520, the vector coordinates are still located in the ring after being translated by the main grating 521 (grating vector Kepe51) in the pupil expansion structure 520, and continue to be totally reflected in the waveguide substrate and deflected and propagated to the coupling-out structure 530; after being acted upon by the auxiliary grating 522 (grating vector Kepe52) in the pupil expansion structure 520, the vector coordinates are translated to the outside of the outer circle, and the light beam does not exist. After being transmitted to the coupling-out structure 530, the vector coordinates are translated into the inner circle by the main grating 531 (grating vector Kout51) in the coupling-out structure 530, and coupled out of the waveguide substrate; after being acted upon by the auxiliary grating 532 (grating vector Kout52) in the coupling-out structure 530, the vector coordinates are translated to the outside of the outer circle, and the light beam does not exist.

参考图11，该图示出了图像光束在图10所示的衍射光波导中传输的K域图.参考图11，图像光束经耦入结构710作用(光栅矢量Kin7)，矢量坐标平移至圆环内，耦入波导基底内全反射传输，传输至扩瞳结构720后，经扩瞳结构720中主光栅721(光栅矢量Kepe71)作用，矢量坐标平移后仍位于圆环内，继续在波导基底内全反射并偏转传播至耦出结构730；经扩瞳结构720中辅助光栅722(光栅矢量Kepe72)作用，矢量坐标平移至外圈之外，光束不存在。传输至耦出结构730后，经耦出结构730中主光栅731(光栅矢量Kout71)作用，矢量坐标平移至内圈内，耦出波导基底；经耦出结构730中辅助光栅732(光栅矢量Kout72)作用，矢量坐标平移至外圈之外，光束不存在。Refer to Figure 11, which shows the K-domain diagram of the image light beam transmitted in the diffraction optical waveguide shown in Figure 10. Referring to Figure 11, the image light beam is acted upon by the coupling structure 710 (grating vector Kin7), and the vector coordinates are translated into the ring, coupled into the waveguide substrate for total reflection transmission, and after being transmitted to the pupil expansion structure 720, the vector coordinates are still located in the ring after being translated by the main grating 721 (grating vector Kepe71) in the pupil expansion structure 720, and continue to be totally reflected in the waveguide substrate and deflected and propagated to the coupling-out structure 730; after being acted upon by the auxiliary grating 722 (grating vector Kepe72) in the pupil expansion structure 720, the vector coordinates are translated outside the outer circle, and the light beam does not exist. After being transmitted to the out-coupling structure 730, the vector coordinates are translated to the inner circle by the main grating 731 (grating vector Kout71) in the out-coupling structure 730, and the waveguide base is coupled out; and the vector coordinates are translated to the outside of the outer circle by the auxiliary grating 732 (grating vector Kout72) in the out-coupling structure 730, and the light beam does not exist.

由此可见，辅助光栅的周期应当被设置为满足在辅助光栅作用后，光束波矢的矢量坐标平移至外圈外，也即满足式(1)所示的关系。It can be seen that the period of the auxiliary grating should be set to satisfy that after the auxiliary grating acts, the vector coordinates of the beam wave vector are translated to the outside of the outer circle, that is, to satisfy the relationship shown in formula (1).

示例性的，本发明提供的衍射光波导中扩瞳结构包括二维光栅结构，且扩瞳结构中的二维光栅结构的不同区域的光栅占空比被调制，以使得在衍射光波导中，沿图像光束传播的方向，扩瞳结构的转折效率逐渐增大。Exemplarily, the pupil expansion structure in the diffraction optical waveguide provided by the present invention includes a two-dimensional grating structure, and the grating duty cycle of different regions of the two-dimensional grating structure in the pupil expansion structure is modulated so that in the diffraction optical waveguide, along the direction of propagation of the image light beam, the turning efficiency of the pupil expansion structure gradually increases.

示例性的，本发明提供的衍射光波导中扩瞳结构包括二维光栅结构和一维光栅结构，且扩瞳结构中的二维光栅结构的不同区域的光栅占空比以及一维光栅结构的光栅占空比被调制，以使得在衍射光波导中，沿图像光束传播的方向，扩瞳结构的转折效率逐渐增大。 Exemplarily, the pupil expansion structure in the diffraction optical waveguide provided by the present invention includes a two-dimensional grating structure and a one-dimensional grating structure, and the grating duty ratio of different regions of the two-dimensional grating structure in the pupil expansion structure and the grating duty ratio of the one-dimensional grating structure are modulated so that in the diffraction optical waveguide, along the direction of propagation of the image light beam, the turning efficiency of the pupil expansion structure gradually increases.

示例性的，本发明提供的衍射光波导中耦出结构包括二维光栅结构，且耦出结构中的二维光栅结构的不同区域的光栅占空比被调制，以使得在衍射光波导中，沿图像光束传播的方向，耦出结构的耦出效率逐渐增大。Exemplarily, the out-coupling structure in the diffraction optical waveguide provided by the present invention includes a two-dimensional grating structure, and the grating duty cycle of different regions of the two-dimensional grating structure in the out-coupling structure is modulated so that in the diffraction optical waveguide, along the direction of propagation of the image light beam, the out-coupling efficiency of the out-coupling structure gradually increases.

示例性的，本发明提供的衍射光波导中耦出结构包括二维光栅结构和一维光栅结构，且耦出结构中的二维光栅结构的不同区域的光栅占空比以及一维光栅结构的光栅占空比被调制，以使得在衍射光波导中，沿图像光束传播的方向，耦出结构的耦出效率逐渐增大。Exemplarily, the out-coupling structure in the diffraction optical waveguide provided by the present invention includes a two-dimensional grating structure and a one-dimensional grating structure, and the grating duty ratio of different regions of the two-dimensional grating structure and the grating duty ratio of the one-dimensional grating structure in the out-coupling structure are modulated so that in the diffraction optical waveguide, along the direction of propagation of the image light beam, the out-coupling efficiency of the out-coupling structure gradually increases.

如图7所示，衍射光波导200包括耦入结构201、扩瞳结构202、耦出结构203和波导基底204，其中，扩瞳结构202的不同区域为占空比不同的二维光栅结构10或一维光栅结构20，光束传播较近的区域不需要高的衍射效率，可选用二维光栅结构10，光束传播较远的区域需要相对较高的衍射效率，可选用一维光栅结构20，同理，耦出结构203的光栅布局也类似。As shown in FIG7 , the diffraction optical waveguide 200 includes a coupling-in structure 201, a pupil expansion structure 202, a coupling-out structure 203 and a waveguide substrate 204, wherein different regions of the pupil expansion structure 202 are two-dimensional grating structures 10 or one-dimensional grating structures 20 with different duty cycles. Regions where the light beam propagates closer do not require high diffraction efficiency, and the two-dimensional grating structure 10 can be used. Regions where the light beam propagates farther require relatively high diffraction efficiency, and the one-dimensional grating structure 20 can be used. Similarly, the grating layout of the coupling-out structure 203 is similar.

需要说明的是，图7中对于扩瞳结构、耦出结构的分区设置仅为示意，还可以有更多的不同占空比的二维光栅结构或者一维光栅结构，二维光栅结构与一维光结构也可交替排布。可以理解，在设计扩瞳结构(耦出结构)中具体的光栅结构时，是以转折效率(耦出效率)为标的进行设计的，设计使得扩瞳结构(耦出结构)中沿着光束传播的方向转折效率(耦出效率)逐渐增大，从而提高光束扩展均匀性(耦出均匀性)。那么对于扩瞳结构(耦出结构)中的任意位置或区域，针对该区域所需要的转折效率(耦出效率)，能达到该转折效率且工艺上占空比较易实现的光栅结构(不论二维光栅结构或者一维光栅结构)都可以成为解。It should be noted that the partition arrangement of the pupil expansion structure and the coupling-out structure in FIG. 7 is only for illustration, and there may be more two-dimensional grating structures or one-dimensional grating structures with different duty ratios, and the two-dimensional grating structure and the one-dimensional optical structure may also be arranged alternately. It can be understood that when designing the specific grating structure in the pupil expansion structure (coupling-out structure), the design is based on the turning efficiency (coupling-out efficiency), and the design makes the turning efficiency (coupling-out efficiency) in the pupil expansion structure (coupling-out structure) along the direction of light beam propagation gradually increase, thereby improving the light beam expansion uniformity (coupling-out uniformity). Then, for any position or area in the pupil expansion structure (coupling-out structure), for the turning efficiency (coupling-out efficiency) required for the area, a grating structure (whether a two-dimensional grating structure or a one-dimensional grating structure) that can achieve the turning efficiency and whose duty ratio is easier to realize in the process can be a solution.

此外，衍射光波导常用的另一种架构与光栅布局，包括沿图像光束传播方向上依次布局的耦入结构和耦出结构。此时衍射光波导不再包括单独的扩瞳结构，耦出结构采用常规的二维光栅同时实现二维扩瞳与耦出，这里常规的二维光栅能衍射产生多个方向的光束传播路径。针对该种架构，为了提高均匀性与效率，通常会对耦出结构进行分区并夹杂布置一维光栅，比如，在耦出结构的两侧区域采用常规一维光栅，在耦出结构的中间区域采用常规二维光栅。这种情形下也会存在前述优化自由度受限，工艺难度大的问题。In addition, another commonly used architecture and grating layout of diffraction waveguides includes a coupling-in structure and a coupling-out structure arranged in sequence along the propagation direction of the image light beam. In this case, the diffraction waveguide no longer includes a separate pupil expansion structure, and the coupling-out structure uses a conventional two-dimensional grating to simultaneously achieve two-dimensional pupil expansion and coupling-out. Here, the conventional two-dimensional grating can diffract to produce beam propagation paths in multiple directions. For this type of architecture, in order to improve uniformity and efficiency, the coupling-out structure is usually partitioned and interspersed with one-dimensional gratings. For example, conventional one-dimensional gratings are used in the two side areas of the coupling-out structure, and conventional two-dimensional gratings are used in the middle area of the coupling-out structure. In this case, there will also be the aforementioned problems of limited optimization freedom and high process difficulty.

根据本发明的另一实施例，提供了一种衍射光波导，包括：波导基底；设置于波导基底表面或内部的耦入结构和耦出结构；耦入结构用于将图像光束耦入波导基底并在波导基底内传输，耦出结构用于将波导基底内传输的图像光束从波导基底中衍射耦出；耦出结构至少包括一二维光栅结构，其中二维光栅结构包括：至少在两个方向上周期性排布的多个光栅单元，其中，在至少两个方向上周期性排布的多个光栅单元被配置，使得图像光束在衍射光波导中的传播路径仅被多个光栅单元在其中一个方向上形成的周期性结构影响。According to another embodiment of the present invention, a diffraction optical waveguide is provided, comprising: a waveguide substrate; a coupling-in structure and a coupling-out structure arranged on the surface or inside of the waveguide substrate; the coupling-in structure is used to couple an image light beam into the waveguide substrate and transmit it within the waveguide substrate, and the coupling-out structure is used to diffract and couple the image light beam transmitted within the waveguide substrate out of the waveguide substrate; the coupling-out structure comprises at least a two-dimensional grating structure, wherein the two-dimensional grating structure comprises: a plurality of grating units arranged periodically in at least two directions, wherein the plurality of grating units arranged periodically in at least two directions are configured so that a propagation path of the image light beam in the diffraction optical waveguide is only affected by a periodic structure formed by the plurality of grating units in one direction.

一种实施方式中，耦出结构分为第一耦出结构、第二耦出结构和第三耦出结构，第二耦出结构位于第一耦出结构和第三耦出结构之间，第一耦出结构和第三耦出结构包括二维光栅结构，该二维光栅结构仅存在一个方向的衍射级次，即衍射产生一个方向的光束传播路径。第二耦出结构包括常规二维光栅结构，该二维光栅结构存在多个方向的衍射级次，即能衍射产生多个方向的光束传播路径。In one embodiment, the coupling structure is divided into a first coupling structure, a second coupling structure and a third coupling structure, the second coupling structure is located between the first coupling structure and the third coupling structure, the first coupling structure and the third coupling structure include a two-dimensional grating structure, and the two-dimensional grating structure has only one square. The second outcoupling structure comprises a conventional two-dimensional grating structure, which has diffraction orders in multiple directions, that is, it can diffract to generate beam propagation paths in multiple directions.

进一步地，第一耦出结构和第三耦出结构还包括一维光栅结构，第一耦出结构和第三耦出结构中二维光栅结构的不同区域的光栅占空比以及一维光栅结构的光栅占空比被调制，以使得在衍射光波导中，沿图像光束传播的方向，第一耦出结构的衍射效率逐渐增大、第三耦出结构的衍射效率逐渐增大。Furthermore, the first out-coupling structure and the third out-coupling structure also include a one-dimensional grating structure, and the grating duty ratios of different regions of the two-dimensional grating structure in the first out-coupling structure and the third out-coupling structure and the grating duty ratio of the one-dimensional grating structure are modulated so that in the diffraction optical waveguide, along the propagation direction of the image light beam, the diffraction efficiency of the first out-coupling structure gradually increases and the diffraction efficiency of the third out-coupling structure gradually increases.

这样，在设置常规一维光栅结构的区域部分或全部替换为本发明前述实施例中提供的二维光栅结构，光束在衍射光波导中的传播路径仅被其在其中一个方向上形成的周期性结构影响，而其他方向形成的周期性结构不影响光束在二维光栅中的传播方向，这样便不会改变原来的光束传播路径。这使得衍射光波导的耦出结构可以通过增加周期性结构的维度来极大提高通过调制占空比优化均匀性的自由度，而且不会因为周期性结构维度的增加引入新的光束传播路径而加大优化均匀性的复杂度，通过光栅占空比优化自由度的提升还能减小工艺难度和工艺成本。In this way, when the area where the conventional one-dimensional grating structure is set is partially or completely replaced with the two-dimensional grating structure provided in the above-mentioned embodiment of the present invention, the propagation path of the light beam in the diffraction optical waveguide is only affected by the periodic structure formed in one direction, while the periodic structure formed in other directions does not affect the propagation direction of the light beam in the two-dimensional grating, so that the original light beam propagation path will not be changed. This allows the outcoupling structure of the diffraction optical waveguide to greatly improve the degree of freedom of optimizing uniformity by modulating the duty cycle by increasing the dimension of the periodic structure, and will not increase the complexity of optimizing uniformity by introducing a new light beam propagation path due to the increase in the dimension of the periodic structure. The improvement of the degree of freedom of optimizing the grating duty cycle can also reduce the process difficulty and process cost.

根据本发明的一实施例，还提供了一种AR设备，包括本发明前述实施例任一项所述的衍射光波导。According to an embodiment of the present invention, there is further provided an AR device, comprising the diffractive optical waveguide as described in any one of the aforementioned embodiments of the present invention.

最后应说明的是：以上各实施例仅用以说明本发明的技术方案，而非对其限制；尽管参照前述各实施例对本发明进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本发明各实施例技术方案的范围。 Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

一种二维光栅结构，用于衍射光波导的扩瞳结构和/或耦出结构，其特征在于，所述二维光栅结构包括：至少在两个方向上周期性排布的多个光栅单元，其中，在所述至少两个方向上周期性排布的所述多个光栅单元被配置为：使得光束在所述衍射光波导中的传播路径仅被所述多个光栅单元在其中一个方向上形成的周期性结构影响。A two-dimensional grating structure, used for a pupil expansion structure and/or outcoupling structure of a diffraction optical waveguide, characterized in that the two-dimensional grating structure comprises: a plurality of grating units arranged periodically in at least two directions, wherein the plurality of grating units arranged periodically in the at least two directions are configured so that the propagation path of the light beam in the diffraction optical waveguide is only affected by the periodic structure formed by the plurality of grating units in one direction.
根据权利要求1所述的二维光栅结构，其特征在于，所述其中一个方向为目标方向，所述至少两个方向中除所述目标方向外的方向为其他方向，所述多个光栅单元在所述其它方向上形成的周期性结构被配置为：所述其它方向上形成的周期性结构的周期适配于所述光束的波长以及所述衍射光波导的波导基底的折射率，以使得所述光束在所述衍射光波导中的传播路径不被所述其它方向上形成的周期性结构影响。The two-dimensional grating structure according to claim 1 is characterized in that one of the directions is a target direction, and the directions other than the target direction among the at least two directions are other directions, and the periodic structures formed by the multiple grating units in the other directions are configured as follows: the period of the periodic structure formed in the other directions is adapted to the wavelength of the light beam and the refractive index of the waveguide substrate of the diffractive optical waveguide, so that the propagation path of the light beam in the diffractive optical waveguide is not affected by the periodic structure formed in the other directions.
根据权利要求2所述的二维光栅结构，其特征在于，所述多个光栅单元在所述其他方向中的第i个方向上形成的周期性结构的周期被配置为可选范围内的最大值，所述可选范围表征了所述光束在所述衍射光波导中的传播路径仅被所述多个光栅单元在所述目标方向上形成的周期性结构影响时，所述多个光栅单元在所述第i个方向上形成的周期性结构的周期的取值。The two-dimensional grating structure according to claim 2 is characterized in that the period of the periodic structure formed by the multiple grating units in the i-th direction among the other directions is configured as a maximum value within an optional range, and the optional range represents the value of the period of the periodic structure formed by the multiple grating units in the i-th direction when the propagation path of the light beam in the diffraction optical waveguide is only affected by the periodic structure formed by the multiple grating units in the target direction.
根据权利要求2所述的二维光栅结构，其特征在于，所述多个光栅单元在其它方向上形成的周期性结构还被配置为：使得光束在所述衍射光波导中的衍射效率被所述多个光栅单元在所述目标方向和所述其他方向上形成的周期性结构共同影响。The two-dimensional grating structure according to claim 2 is characterized in that the periodic structure formed by the multiple grating units in other directions is further configured so that the diffraction efficiency of the light beam in the diffraction optical waveguide is jointly affected by the periodic structure formed by the multiple grating units in the target direction and the other directions.
根据权利要求1所述的二维光栅结构，其特征在于，所述二维光栅结构的不同位置的影响所述二维光栅结构的衍射效率的光栅参数不同，以调节所述光束在所述二维光栅结构作用下扩瞳和/或耦出的均匀性。The two-dimensional grating structure according to claim 1 is characterized in that grating parameters affecting the diffraction efficiency of the two-dimensional grating structure are different at different positions of the two-dimensional grating structure, so as to adjust the uniformity of pupil expansion and/or outcoupling of the light beam under the action of the two-dimensional grating structure.
根据权利要求5所述的二维光栅结构，其特征在于，所述二维光栅结构被配置为：通过配置所述二维光栅结构的不同区域的光栅占空比，以使得在所述衍射光波导中，沿光束传播的方向，所述二维光栅结构的衍射效率逐渐增大，以调节光束在所述二维光栅结构作用下扩瞳或者耦出的均匀性。The two-dimensional grating structure according to claim 5 is characterized in that the two-dimensional grating structure is configured as follows: by configuring the grating duty ratio of different regions of the two-dimensional grating structure, the diffraction efficiency of the two-dimensional grating structure gradually increases along the direction of light beam propagation in the diffraction waveguide, so as to adjust the uniformity of pupil expansion or outcoupling of the light beam under the action of the two-dimensional grating structure.
一种扩瞳结构，包括权利要求1-6任一项所述的光栅结构。A pupil expansion structure, comprising the grating structure according to any one of claims 1 to 6.
根据权利要求7所述的扩瞳结构，其特征在于，所述扩瞳结构还包括一维光栅结构，且所述扩瞳结构中沿着光束传播的方向转折效率依次增大。The pupil expansion structure according to claim 7 is characterized in that the pupil expansion structure also includes a one-dimensional grating structure, and the turning efficiency in the pupil expansion structure increases successively along the direction of light beam propagation.
一种耦出结构，包括权利要求1-6任一项所述的光栅结构。A coupling-out structure comprises the grating structure according to any one of claims 1 to 6.
根据权利要求9所述的耦出结构，其特征在于，所述耦出结构还包括一维光栅结构，且所述耦出结构中沿着光束传播的方向耦出效率依次增大。The out-coupling structure according to claim 9 is characterized in that the out-coupling structure also includes a one-dimensional grating structure, and the out-coupling efficiency in the out-coupling structure increases successively along the direction of light beam propagation.
一种衍射光波导，其特征在于，包括：A diffractive optical waveguide, characterized by comprising:

波导基底；waveguide substrate;

设置于所述波导基底表面或内部的耦入结构和耦出结构，或者，设置于所述波导基底表面或内部的耦入结构、扩瞳结构和耦出结构；所述耦入结构用于将图像光束耦入所述波导基底并在所述波导基底内传输，所述扩瞳结构用于将所述图像光束扩展传输至所述耦出结构，所述耦出结构用于将所述波导基底内传输的所述图像光束从所述波导基底中衍射耦出；A coupling structure and an outcoupling structure are arranged on the surface or inside of the waveguide substrate, or a coupling structure, a pupil expansion structure and an outcoupling structure are arranged on the surface or inside of the waveguide substrate; the coupling structure The image light beam is coupled into the waveguide substrate and transmitted in the waveguide substrate, the pupil expansion structure is used to expand the image light beam and transmit it to the outcoupling structure, and the outcoupling structure is used to diffract and couple the image light beam transmitted in the waveguide substrate out of the waveguide substrate;

所述扩瞳结构和/或所述耦出结构至少包括一二维光栅结构，其中所述二维光栅结构包括：至少在两个方向上周期性排布的多个光栅单元，其中，在所述至少两个方向上周期性排布的所述多个光栅单元被配置为：使得所述图像光束在所述衍射光波导中的传播路径仅被所述多个光栅单元在其中一个方向上形成的周期性结构影响。The pupil expansion structure and/or the outcoupling structure includes at least a two-dimensional grating structure, wherein the two-dimensional grating structure includes: a plurality of grating units arranged periodically in at least two directions, wherein the plurality of grating units arranged periodically in the at least two directions are configured so that a propagation path of the image light beam in the diffraction optical waveguide is only affected by the periodic structure formed by the plurality of grating units in one direction.
根据权利要求11所述的衍射光波导，其特征在于，所述多个光栅单元在其它方向上形成的周期性结构被配置为：在其它方向上形成的周期性结构的周期适配于所述图像光束的波长以及所述波导基底的折射率，以使得所述图像光束在所述衍射光波导中的传播路径不被所述其它方向上形成的周期性结构影响；其中，所述其中一个方向为目标方向，所述其他方向表征了所述至少两个方向中除所述目标方向外的方向。The diffractive optical waveguide according to claim 11 is characterized in that the periodic structures formed by the plurality of grating units in other directions are configured as follows: the period of the periodic structures formed in other directions is adapted to the wavelength of the image light beam and the refractive index of the waveguide substrate, so that the propagation path of the image light beam in the diffractive optical waveguide is not affected by the periodic structures formed in other directions; wherein one of the directions is a target direction, and the other directions represent directions other than the target direction in the at least two directions.
根据权利要求12所述的衍射光波导，其特征在于，所述衍射光波导包括耦入结构、扩瞳结构和耦出结构，所述扩瞳结构和/或所述耦出结构包括所述二维光栅结构，在所述扩瞳结构中的目标方向为第一目标方向，在所述耦出结构中的目标方向为第二目标方向，所述第一目标方向和所述第二目标方向表征不同的方向。The diffractive optical waveguide according to claim 12 is characterized in that the diffractive optical waveguide includes a coupling-in structure, a pupil expansion structure and a coupling-out structure, the pupil expansion structure and/or the coupling-out structure include the two-dimensional grating structure, the target direction in the pupil expansion structure is a first target direction, the target direction in the coupling-out structure is a second target direction, and the first target direction and the second target direction represent different directions.
根据权利要求12所述的衍射光波导，其特征在于，所述多个光栅单元在其它方向中的第i个方向上形成的周期性结构的周期被配置为符合以下公式：
The diffractive optical waveguide according to claim 12, characterized in that the period of the periodic structure formed by the plurality of grating units in the i-th direction in the other directions is configured to conform to the following formula:

其中，(K_x0，K_y0)为所述图像光束被所述多个光栅单元在第i个方向上形成的周期性结构作用前的K矢量坐标，m为衍射级次，n为所述波导基底的折射率，λ为光束的波长，d_i为所述多个光栅单元在第i个方向上形成的周期性结构的周期，θ是所述多个光栅单元在第i个方向上形成的周期性结构的光栅矢量与矢量坐标系中x轴的夹角，(K_x0+m*(2π/d_i)cosθ，K_y0+m*(2π/d_i)sinθ)为所述图像光束被所述多个光栅单元在第i个方向上形成的周期性结构作用后的K矢量坐标。Wherein, ( _Kx0 , _Ky0 ) is the K vector coordinate of the image light beam before being acted upon by the periodic structure formed by the multiple grating units in the i-direction, m is the diffraction order, n is the refractive index of the waveguide substrate, λ is the wavelength of the light beam, d _i is the period of the periodic structure formed by the multiple grating units in the i-direction, θ is the angle between the grating vector of the periodic structure formed by the multiple grating units in the i-direction and the x-axis in the vector coordinate system, and ( _Kx0 +m*(2π/d _i )cosθ, _Ky0 +m*(2π/d _i )sinθ) is the K vector coordinate of the image light beam after being acted upon by the periodic structure formed by the multiple grating units in the i-direction.
根据权利要求14所述的衍射光波导，其特征在于，所述多个光栅单元在第i个方向上形成的周期性结构的周期被配置为可选范围内的最大值，所述可选范围表征了所述图像光束在所述衍射光波导中的传播路径仅被所述多个光栅单元在其中一个方向上形成的周期性结构影响时，所述多个光栅单元在第i个方向上形成的周期性结构的周期的取值。The diffractive optical waveguide according to claim 14 is characterized in that the period of the periodic structure formed by the multiple grating units in the i-th direction is configured as a maximum value within an optional range, and the optional range represents the value of the period of the periodic structure formed by the multiple grating units in the i-th direction when the propagation path of the image light beam in the diffractive optical waveguide is only affected by the periodic structure formed by the multiple grating units in one direction.
根据权利要求11所述的衍射光波导，其特征在于，所述二维光栅结构被配置为：通过配置所述二维光栅结构的不同区域的光栅占空比，以使得在所述衍射光波导中，沿光束传播的方向，所述二维光栅结构的衍射效率逐渐增大，以调节经过所述二维光栅结构作用后的光束的均匀性。The diffraction optical waveguide according to claim 11, characterized in that the two-dimensional grating structure is configured as follows: by configuring the grating duty ratios of different regions of the two-dimensional grating structure, the diffraction efficiency of the two-dimensional grating structure gradually increases along the direction of light beam propagation in the diffraction optical waveguide. The value is gradually increased to adjust the uniformity of the light beam after being acted upon by the two-dimensional grating structure.
根据权利要求16所述的衍射光波导，其特征在于，所述衍射光波导包括耦入结构、扩瞳结构和耦出结构；The diffractive optical waveguide according to claim 16, characterized in that the diffractive optical waveguide comprises an incoupling structure, a pupil expansion structure and an outcoupling structure;

其中，所述扩瞳结构包括二维光栅结构，所述扩瞳结构中的二维光栅结构的不同区域的光栅占空比被调制，以使得在所述衍射光波导中，沿所述图像光束传播的方向，所述扩瞳结构的转折效率逐渐增大，和/或，The pupil expansion structure includes a two-dimensional grating structure, and the grating duty ratios of different regions of the two-dimensional grating structure in the pupil expansion structure are modulated so that in the diffraction optical waveguide, along the propagation direction of the image light beam, the turning efficiency of the pupil expansion structure gradually increases, and/or,

所述耦出结构包括二维光栅结构，所述耦出结构中的二维光栅结构的不同区域的光栅占空比，以使得在所述衍射光波导中，沿所述图像光束传播的方向，所述耦出结构的耦出效率逐渐增大。The outcoupling structure comprises a two-dimensional grating structure, and the grating duty ratios of different regions of the two-dimensional grating structure in the outcoupling structure are such that the outcoupling efficiency of the outcoupling structure gradually increases along the propagation direction of the image light beam in the diffraction optical waveguide.
根据权利要求17所述的衍射光波导，其特征在于，所述扩瞳结构包括二维光栅结构和一维光栅结构，所述扩瞳结构中二维光栅结构的不同区域的光栅占空比以及一维光栅结构的光栅占空比被调制，以使得在所述衍射光波导中，沿所述图像光束传播的方向，所述扩瞳结构的转折效率逐渐增大。The diffraction optical waveguide according to claim 17 is characterized in that the pupil expansion structure includes a two-dimensional grating structure and a one-dimensional grating structure, and the grating duty ratio of different regions of the two-dimensional grating structure and the grating duty ratio of the one-dimensional grating structure in the pupil expansion structure are modulated so that in the diffraction optical waveguide, along the propagation direction of the image light beam, the turning efficiency of the pupil expansion structure gradually increases.
根据权利要求17所述的衍射光波导，其特征在于，所述耦出结构包括二维光栅结构和一维光栅结构，所述耦出结构中二维光栅结构的不同区域的光栅占空比以及一维光栅结构的光栅占空比被调制，以使得在所述衍射光波导中，沿所述图像光束传播的方向，所述耦出结构的耦出效率逐渐增大。The diffraction optical waveguide according to claim 17 is characterized in that the out-coupling structure includes a two-dimensional grating structure and a one-dimensional grating structure, and the grating duty ratio of different regions of the two-dimensional grating structure and the grating duty ratio of the one-dimensional grating structure in the out-coupling structure are modulated so that in the diffraction optical waveguide, along the propagation direction of the image light beam, the out-coupling efficiency of the out-coupling structure gradually increases.
根据权利要求11所述的衍射光波导，其特征在于，所述扩瞳结构的光栅深度与所述耦出结构的光栅深度一致。The diffractive optical waveguide according to claim 11, characterized in that the grating depth of the pupil expansion structure is consistent with the grating depth of the outcoupling structure.
根据权利要求11所述的衍射光波导，其特征在于，所述衍射光波导包括耦入结构和耦出结构，所述耦出结构分为第一耦出结构、第二耦出结构和第三耦出结构，所述第二耦出结构位于所述第一耦出结构和所述第三耦出结构之间，所述第一耦出结构和所述第三耦出结构包括所述二维光栅结构。The diffractive optical waveguide according to claim 11 is characterized in that the diffractive optical waveguide includes a coupling-in structure and a coupling-out structure, the coupling-out structure is divided into a first coupling-out structure, a second coupling-out structure and a third coupling-out structure, the second coupling-out structure is located between the first coupling-out structure and the third coupling-out structure, and the first coupling-out structure and the third coupling-out structure include the two-dimensional grating structure.
根据权利要求21所述的衍射光波导，其特征在于，所述第一耦出结构和所述第三耦出结构还包括一维光栅结构，所述第一耦出结构和所述第三耦出结构中所述二维光栅结构的不同区域的光栅占空比以及所述一维光栅结构的光栅占空比被调制，以使得在所述衍射光波导中，沿所述图像光束传播的方向，所述第一耦出结构和所述第三耦出结构的衍射效率逐渐增大。 The diffraction optical waveguide according to claim 21 is characterized in that the first out-coupling structure and the third out-coupling structure also include a one-dimensional grating structure, and the grating duty ratios of different regions of the two-dimensional grating structure in the first out-coupling structure and the third out-coupling structure and the grating duty ratio of the one-dimensional grating structure are modulated so that in the diffraction optical waveguide, along the propagation direction of the image light beam, the diffraction efficiency of the first out-coupling structure and the third out-coupling structure gradually increases.