CN116540340A - Grating structure and manufacturing method of diffraction optical waveguide - Google Patents

Grating structure and manufacturing method of diffraction optical waveguide Download PDF

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Publication number
CN116540340A
CN116540340A CN202310451215.4A CN202310451215A CN116540340A CN 116540340 A CN116540340 A CN 116540340A CN 202310451215 A CN202310451215 A CN 202310451215A CN 116540340 A CN116540340 A CN 116540340A
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grating
substrate
material layer
grating material
grating structure
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陈和峰
陈志高
楼歆晔
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Shanghai Kunyou Technology Co ltd
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Shanghai Kunyou Technology Co ltd
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/18—Diffraction gratings
    • G02B5/1847—Manufacturing methods
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/18—Diffraction gratings
    • G02B5/1847—Manufacturing methods
    • G02B5/1857—Manufacturing methods using exposure or etching means, e.g. holography, photolithography, exposure to electron or ion beams
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0015—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/0016—Grooves, prisms, gratings, scattering particles or rough surfaces
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0023—Means for improving the coupling-in of light from the light source into the light guide provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
    • G02B6/0026—Wavelength selective element, sheet or layer, e.g. filter or grating
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0065—Manufacturing aspects; Material aspects

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Diffracting Gratings Or Hologram Optical Elements (AREA)

Abstract

The invention provides a method for manufacturing a grating structure, which is used for a pupil expanding structure and/or a coupling-out structure, and comprises the following steps: providing a substrate; localized air-lock etching is performed on different locations of the substrate to form a rugged surface profile on different locations of the first surface of the substrate; depositing a grating material layer on the first surface of the substrate, and carrying out planarization treatment on the top of the grating material layer so as to planarize the top of the grating material layer; the thickness of the grating material layer is unevenly distributed, so that when the grating material layer is etched to form a grating structure, the depth change of the grating structure enables the diffraction efficiency of the grating structure to be gradually increased along the light propagation direction; forming a patterned mask layer on top of the grating material layer; etching the grating material layer to the first surface by taking the patterned mask layer as a mask so as to form a grating structure on the substrate; the patterned mask layer is removed. The scheme provided by the invention can solve the problem of how to manufacture the depth modulation grating structure.

Description

Grating structure and manufacturing method of diffraction optical waveguide
Technical Field
The invention relates to the field of diffraction waveguides, in particular to a grating structure and a manufacturing method of a diffraction optical waveguide.
Background
Augmented reality is a technology of integrating real world and virtual information, a diffraction optical waveguide is one of modes of realizing the technology, at present, the diffraction optical waveguide on the market is generally divided into a volume holographic waveguide and a surface relief grating waveguide, the essence of the diffraction optical waveguide is that incident light is coupled into the waveguide through grating diffraction, and the surface relief grating waveguide has obvious advantages in a plurality of schemes due to extremely high design freedom and mass productivity caused by nano imprinting processing. In addition, in order to make the light output from the diffractive optical waveguide more uniform, different grating parameters are usually set in different areas of pupil expansion and/or coupling out, and the nanoimprint manner can be well realized. However, the diffraction optical waveguide prepared by nano-imprinting generally uses an imprinting glue material as a grating material, and is limited by the refractive index of the imprinting glue material, so that the prepared grating structure and diffraction optical waveguide have difficulty in achieving high diffraction efficiency with different wavelengths and large field angles.
In the conventional diffraction waveguide, in order to make the light beam emitted by the coupling-out grating or the pupil expansion grating more uniform, grating units with different depths are generally arranged, and the manufacturing process of the grating units with different depths is relatively difficult, and in the prior art, the following technical methods are generally adopted:
1. imprinting the imprinting master onto the imprinting gel by utilizing the depth-modulated imprinting master to prepare grating structures with different depths;
2. forming a patterned mask on a substrate, forming a sacrificial layer with the surface fluctuation on the patterned mask, and etching the substrate by taking the patterned mask and the sacrificial layer with the surface fluctuation as masks, thereby forming grating structures with different depths;
3. sequentially forming an etching stop layer and a grating material layer with uneven surface on a substrate, forming a patterned mask layer on the surface of the grating material layer, and etching the grating material layer by taking the patterned mask layer as a mask to form a grating structure.
However, the above prior art has the following drawbacks:
for the above-mentioned process method 1, an imprint rubber material is required to be used as a grating material, and the imprint process is limited by the refractive index of the imprint rubber material (usually, the refractive index is higher and only about 1.9), so that it is difficult to achieve high diffraction efficiency with different wavelengths and large field angles, resulting in an imprintable grating structure.
For the technical means 2 of the process method, because the gray scale lithography mode is adopted, the controllability is low, and the process difficulty of forming the sacrificial layer with ideal non-uniform thickness is high.
For the above-mentioned process method 3, multiple etching processes are required, and there is also a problem of low controllability, the same process parameters have differences in etching results in different processes, and an additional etching stop layer is required, and at the same time, when a mask layer is formed on the surface of the grating material layer and patterning is performed, the patterning process is difficult due to the rugged surface, and the operation is inconvenient.
In addition, for those skilled in the art, in the actual imprinting or etching process, the stability of the structure cannot be ensured by different batches of grating structures prepared by the same imprinting master or multiple etching processes, so that the diffraction effects of the grating structures of different batches are different.
Therefore, the invention provides a grating structure and a manufacturing method of a diffraction optical waveguide based on possible problems in the prior art.
Disclosure of Invention
The invention provides a grating structure and a manufacturing method of a diffraction optical waveguide, which are based on the expected grating depth distribution, the difference requirements among different grating depths and the superiority of localized air-pocket corrosion, and the localized air-pocket corrosion is used for carrying out time-sharing partition operation at different positions of a substrate to form a contour structure with uneven surface, so that the problems that the grating structure modulated by grating parameters is manufactured, and the uniformity of different wavelengths and different angles of view under a large view field can be considered, the grating structure with uniform change of depth is manufactured, the abrupt change of light beams caused by depth fault is avoided, meanwhile, the method can overcome the difference caused by etching parameters of the same process in the etching process of different substrates, ensure the consistency of grating structures of different process batches, realize the repeatability of the process and ensure the stability of the grating and waveguide structure performance.
According to a first aspect of the present invention, there is provided a method of manufacturing a grating structure for a pupil expanding structure and/or a coupling-out structure of a diffractive optical waveguide, comprising:
s11, providing a substrate;
s12, carrying out localized air cluster corrosion treatment of time-sharing partition on the substrate based on expected grating depth distribution and difference requirements among different grating depths, and controlling the size of a beam spot and the moving step length so as to form a rugged surface profile at different positions of the first surface of the substrate;
s13, depositing a grating material layer on the first surface of the substrate, and carrying out planarization treatment on the top of the grating material layer so as to enable the top of the grating material layer to be flat; the thickness of the grating material layer is unevenly distributed, so that when the grating material layer is etched to form the grating structure, the depth of the grating structure changes, and the diffraction efficiency of the grating structure along the light propagation direction is gradually increased;
s14, forming a patterned mask layer on the top of the grating material layer;
s15, etching the grating material layer to the first surface by taking the patterned mask layer as a mask so as to form the grating structure on the substrate;
and S16, removing the patterned mask layer to obtain the grating structure.
The localized air mass corrosion refers to the method that the size of beam spots and the moving step length of a particle beam are controlled by taking the size of the beam spots of the particle beam as a reference, and the regional corrosion is carried out by the chemical action of gas according to the reference.
The substrate refers to Si and SiO 2 High refractive index glass (HRI), resin, etc.; the gas means C 4 F 8 、NF 3 、He、O 2 Ar or a mixture of any of the foregoing.
Optionally, in step S12, the substrate is subjected to localized air-lock etching based on the expected grating depth distribution and the difference requirement between the different grating depths to form a rugged surface profile at different locations on the first surface of the substrate, including:
the substrate is processed by applying a particle beam to different locations of the substrate in localized air mass erosion based on the desired grating depth profile and the difference requirements between the different grating depths, and the processing depths of the different locations of the first surface of the substrate are modulated by modulating the energy and/or residence time of the particle beam corresponding to the particle beam at the different locations of the first surface of the substrate to form a bumpy surface profile at the different locations of the first surface of the substrate.
Optionally, the size of the particle beam is smaller than the size of the pupil expanding structure and/or the coupling-out structure, and the size of the particle beam is larger than the grating period of the grating structure.
Optionally, the processing the substrate by the particle beam acting on different positions of the substrate includes:
controlling the particle beam to move along at least two directions to perform time-sharing partition effect so as to treat areas corresponding to different positions of the pupil expanding structure and/or the coupling-out structure on the first surface of the substrate; the two directions are parallel to a plane in which the top of the layer of grating material is located.
Optionally, the undulating surface profile comprises a surface profile that varies stepwise in at least two directions, and the thickness difference between adjacent steps is no greater than 10%.
Optionally, the substrate further includes a second surface opposite to the first surface, a step surface in the step-like varying surface profile is parallel to the second surface, and the grating material layer is formed on a surface of the step.
Optionally, the grating material layer includes a plurality of grating material layers, and the refractive index of each grating material layer is different.
Optionally, the refractive index of each of the grating material layers increases gradually in a direction away from the substrate.
According to a second aspect of the present invention, there is provided a method of manufacturing a diffractive optical waveguide, comprising:
providing a substrate;
based on the expected grating depth distribution and the difference requirements among different grating depths, carrying out localized air cluster corrosion treatment on different positions of the substrate in a time-sharing partition mode, and controlling the size of beam spots and the moving step length to form a rugged surface profile at different positions at least in a pupil expansion area and/or a coupling-out area of the first surface of the substrate;
depositing a grating material layer on the first surface of the substrate, and carrying out planarization treatment on the top of the grating material layer so as to planarize the top of the grating material layer; the thickness of the grating material layer is unevenly distributed, so that when the grating material layer is etched to form a grating structure in the pupil expansion area and/or the coupling-out area, the depth change of the grating structure enables the diffraction efficiency of the grating structure to be gradually increased along the light propagation direction;
forming a patterned mask layer on top of the grating material layer;
etching the grating material layer to the first surface by taking the patterned mask layer as a mask so as to form the grating structure on the substrate;
and removing the patterned mask layer.
Optionally, the shape of the mydriatic region is a closed shape surrounded by a curve and/or a straight line, and the shape of the coupling-out region is a closed shape surrounded by a curve and/or a straight line.
The localized air mass corrosion refers to the method that the size of beam spots and the moving step length of a particle beam are controlled by taking the size of the beam spots of the particle beam as a reference, and the regional corrosion is carried out by the chemical action of gas according to the reference.
The invention provides a manufacturing method of a grating structure, which uses a semiconductor localized air mass etching process, takes the beam spot size of a particle beam as a reference, controls the beam spot size and the moving step length, carries out partition etching by the chemical action of gas, controls specific parameters of the rugged surface profile formed by different areas of the first surface of a substrate and the thickness of a grating material layer based on the expected grating depth distribution and the difference value between different grating depths, so that the rugged surface profile of the substrate is firstly formed by localized air mass etching at different positions of the first surface of the substrate, then forms a grating material layer with flat top on the first surface, and etches the grating material layer to the first surface of the substrate by using a patterned mask layer to form a grating structure on the first surface of the substrate; because the thickness of the substrate is unevenly distributed, after the grating material layer is etched to the first surface of the substrate, the depth of the finally formed grating structure is unevenly distributed, so that specific parameters of the surface profile of the first surface of the substrate forming the undulation and the thickness of the grating material layer can be controlled according to the expected distribution of the grating depth and the difference value between different grating depths, and the depth change of the finally etched grating structure can gradually increase the diffraction efficiency of the grating structure along the light propagation direction so as to achieve the purpose of modulating uniformity. Therefore, the technical scheme provided by the invention creatively provides a novel process method for manufacturing the depth-modulated grating structure, utilizes localized air-cluster corrosion to treat the substrate to enable the substrate to form a surface profile with undulating and uneven, solves the problem of how to manufacture the depth-modulated grating structure, and achieves the purpose of modulation uniformity.
Furthermore, the rough surface profile formed on the first surface of the substrate is processed by the particle beam action in localized air cluster corrosion, and furthermore, the processing process is high in controllability, and besides the processing substrate material, the processing grating material is not limited by the imprinting glue material, so that a foundation is provided for diversified selection of the grating material, and high diffraction efficiency with different wavelengths and large field angles can be considered.
The localized air-cluster corrosion can realize the separate processing of time-sharing and area-dividing, has strong controllability, has substantial difference between the process principle and the process and the conventional etching process, can realize that the substrate is different from the conventional etching grating material, the conventional etching process is difficult to etch the substrate, the localized air-cluster corrosion adopted in the method can process the substrate, the method is different from the conventional etching process, the depth of each area of the substrate is adjustable at any time due to the great difference between the substrate and the processing process of the grating, the different gases are selected based on the substrate, the substantial difference exists between the used process (process route, parameter and the like) and the conventional process by controlling the beam spot size and the moving step length, the controllable degree of the processing process of the substrate is high, the method has the advantages that the degree of freedom is high, the energy of localized air mass corrosion is kept constant in the treatment process under a certain step length, the beam spot size of a particle beam is used as a reference, the substrate treatment time of different areas is controlled based on the grating depth requirement, and reproducible uneven different substrates can be obtained.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that other drawings can be obtained according to these drawings without inventive faculty for a person skilled in the art.
FIG. 1 is a flow chart of a method for fabricating a grating structure according to an embodiment of the present invention;
FIGS. 2-6 are schematic views of a device structure at various stages of a process according to a method of fabricating a grating structure according to an embodiment of the present invention;
reference numerals illustrate:
101-a substrate;
102-a layer of grating material;
103-patterning the mask layer;
104-grating structure.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The terms "first," "second," "third," "fourth" and the like in the description and in the claims and in the above drawings, if any, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
In view of this, the inventor of the present application skillfully uses a semiconductor localized air-cluster etching process, uses the beam spot size of a particle beam as a reference, controls the beam spot size and the moving step length, performs partition etching based on the chemical action of the gas, and controls specific parameters of the rugged surface profile formed on the first surface of the substrate and the thickness of the grating material layer based on the expected grating depth distribution and the difference between different grating depths, so that the rugged surface profile of the substrate is formed, and a grating structure with depth modulation can be formed by forming a grating material layer with flat top on the rugged surface of the substrate and forming a grating material layer with a patterned mask layer on the grating material layer surface, and then performing etching once.
The localized air-cluster corrosion can realize separate processing in time-sharing and area-dividing mode, the process principle and the process are substantially different from those of the conventional etching process, the energy of the localized air-cluster corrosion is kept constant in a certain step length in the processing process, the substrate processing time of different areas is controlled based on the grating depth requirement, and reproducible uneven substrates can be obtained.
Compared with the prior art, the technical scheme provided by the application has the advantages that under the condition that the etching selection ratio between the substrate and the grating material layer is reasonably selected, the process is simple, the etching times can be reduced on the premise of guaranteeing the grating structure, the difficulty of mask patterning can be reduced in the planarization treatment of the top of the grating material layer, the operation is convenient, the efficiency is improved, and unexpected technical effects are achieved.
Because the process has high process controllability, can realize time-sharing partition treatment, and is not limited by the imprinting glue material any more for the grating material except the substrate material treatment, so that the selection of the grating material can be diversified; for example, a high refractive index material may be deposited for use as a layer of grating material.
The technical scheme of the invention is described in detail below by specific examples. The following embodiments may be combined with each other, and some embodiments may not be repeated for the same or similar concepts or processes.
According to an embodiment of the present invention, there is provided a method for manufacturing a grating structure, a flowchart of the method for manufacturing a grating structure is shown in fig. 1, the grating structure is used for a pupil expanding structure and/or a coupling-out structure of a diffractive optical waveguide, the method includes:
s11: providing a substrate 101;
s12: based on the expected grating depth distribution and the difference requirements among different grating depths, carrying out localized air-cluster corrosion treatment on different positions of the substrate 101 in a time-sharing partition mode, and controlling the size of the beam spots and the moving step length to form a rugged surface profile at different positions of the first surface of the substrate 101, as shown in fig. 2;
s13: depositing a grating material layer 102 on a first surface of a substrate 101, and performing planarization treatment on the top of the grating material layer 102 to planarize the top of the grating material layer 102, as shown in fig. 3; because the first surface of the substrate 101 has the uneven surface profile at different positions, the thickness of the grating material layer 102 is unevenly distributed, so that the specific parameters of the uneven surface profile at different positions of the first surface of the substrate and the thickness of the grating material layer can be designed to enable the depth of the grating structure 104 to change and the interface to be in an uneven profile shape when the grating material layer 102 is etched to form the grating structure 104, so that the diffraction efficiency of the grating structure 104 along the light propagation direction is gradually increased;
s14: forming a patterned mask layer 103 on top of the layer of grating material 102, as shown in fig. 4;
s15: etching the grating material layer 102 to the first surface with the patterned mask layer 103 as a mask to form a grating structure 104 on the substrate 101, as shown in fig. 5;
s16: the patterned mask layer 103 is removed as shown in fig. 6.
The localized air mass etching in step S12 refers to the step of controlling the beam spot size and the movement step length based on the beam spot size of the particle beam, and performing the zone etching based on the reference by the chemical action of the gas. The substrate refers to Si and SiO 2 High refractive index glass (HRI), resin, etc.; the gas means C 4 F 8 、NF 3 、He、O 2 Ar or any of the foregoing mixed gases, and the like; the beam spot size may refer to, among other things, the initial size of the device to generate the air mass. The method for manufacturing the grating structure 104 comprises performing localized air-cluster etching treatment on different positions of the first surface of the substrate 101 to form a rugged surface profile, forming a grating material with flat top on the first surfaceA layer 102, and forming a patterned mask layer 103 on top of the grating material layer 102, etching the grating material layer 102 to the first surface of the substrate 101 with the patterned mask layer 103 as a mask to form a grating structure 104 on the first surface of the substrate 101; because the first surface of the substrate 101 is a rough surface profile, the thickness of the substrate 101 is unevenly distributed, and of course, the thickness of the grating material layer 102 deposited on the first surface and having a flat top is also unevenly distributed, and after the grating material layer 102 is etched to the first surface of the substrate 101, the depth of the finally formed grating structure 104 is also unevenly distributed, so that the depth variation of the grating structure 104 causes the diffraction efficiency of the grating structure 104 to be gradually increased along the direction of light propagation so as to achieve the purpose of uniformity modulation; the preparation of reproducible uneven substrates is realized through localized air-cluster corrosion treatment, so that the etching process times can be effectively reduced, and the production efficiency can be improved.
Therefore, the technical scheme provided by the invention creatively provides a novel process method for manufacturing the depth-modulated grating structure, and the novel process method is based on the substrate with the rugged surface profile, so that a novel solution is provided for solving the problem of how to manufacture the depth-modulated grating structure.
In one embodiment, in step S12, localized air-cluster etching is performed on different locations of the substrate 101 based on the expected grating depth distribution and the difference requirement between the different grating depths to form a rugged surface profile on different locations of the first surface of the substrate 101, including:
the treatment depth for different locations of the first surface of the substrate 101 is modulated by treating the different locations of the first surface of the substrate 101 with a particle beam and modulating the energy and/or residence time of the particle beam at the corresponding different locations of the first surface of the substrate 101 to form a contoured surface profile at the different locations of the first surface of the substrate 101.
Wherein localized air mass etching refers to the step of controlling the beam spot size and the moving step length based on the beam spot size of the particle beam, and performing zone etching based on the reference by chemical action of gas.
Specifically, according to diffraction efficiency requirements of the grating, calculating and simulating the distribution condition of each depth in the grating structure area and the height difference of each grating unit, setting the height value of each grating unit based on the design standard that the step thickness difference of adjacent different depths is not more than 10%, further obtaining the processing height of the substrate, obtaining different processing depths based on the thickness of the substrate, and forming the rugged profile at different positions of the first surface of the substrate. The method specifically comprises the following steps:
at the depth of the shallowest grating depth min Calculating the rest depths and the depth as reference min And record the difference between the grating position and depth (position S&Delta) correspondence;
then controlling the localized air mass corrosion treatment process according to the corresponding relation; the method specifically comprises the following steps: the amount of particles and/or the residence time at the location S is controlled to obtain the respective depth delta, thereby forming a relief surface profile in the grating structure region of the first surface.
Wherein the thickness of the shallowest part of the deposited grating material layer is depth min The thickness is the distance from the initial position of the first surface of the substrate to the top of the grating material layer.
In one embodiment, the size of the electron beam is smaller than the size of the pupil expanding structure and/or the coupling-out structure, and the size of the electron beam is larger than the grating period of the grating structure 104.
In one embodiment, processing the substrate 101 by electron beams acting on different locations of the substrate 101 includes:
controlling the particle beam to move along at least two directions for time-sharing partition effect so as to treat the corresponding areas of the pupil expanding structure and/or the coupling-out structure at different positions of the first surface of the substrate 101; both directions are parallel to the plane in which the top of the layer of grating material 102 lies.
In one embodiment, the undulating surface profile comprises a surface profile that varies stepwise in at least two directions, and the thickness of adjacent steps differs by no more than 10%.
In one embodiment, the substrate 101 further includes a second surface opposite the first surface, the step surface in the step-like varying surface profile being parallel to the second surface, and the layer of grating material 102 is formed on the surface of the step. It will be appreciated that the first surface of the substrate 101 comprises a plurality of successive steps and that the undulating surface profile is an overall topography formed by the plurality of successive steps, only such an undulating overall topography being illustrated in the drawings.
In one embodiment, the grating material layer 102 includes several grating material layers, each having a different refractive index.
In one embodiment, the refractive index of each grating material layer increases gradually in a direction away from the substrate 101.
Next, according to an embodiment of the present invention, there is also provided a method for manufacturing a diffractive optical waveguide, including:
providing a substrate 101;
based on the expected grating depth distribution and the difference requirements among different grating depths, carrying out localized air-cluster corrosion treatment on different positions of the substrate 101 in a time-sharing partition mode, and controlling the size of the beam spots and the moving step length so as to form a rugged surface profile at different positions of the first surface of the substrate 101;
depositing a grating material layer 102 on a first surface of a substrate 101, and performing planarization treatment on the top of the grating material layer 102 to planarize the top of the grating material layer 102; the thickness of the grating material layer 102 is unevenly distributed, so that when the grating material layer 102 is etched to form the grating structure 104 in the pupil expansion area and/or the coupling-out area, the depth of the grating structure 104 changes, so that the diffraction efficiency of the grating structure 104 along the light propagation direction is gradually increased;
forming a patterned mask layer 103 on top of the grating material layer 102;
etching the grating material layer 102 to the first surface with the patterned mask layer 103 as a mask to form a grating structure 104 on the substrate 101;
the patterned mask layer 103 is removed. In an embodiment, the shape of the mydriatic region is a closed shape enclosed by a curve and/or a straight line, and the shape of the coupling-out region is a closed shape enclosed by a curve and/or a straight line.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims (10)

1. A method of manufacturing a grating structure for a pupil expanding structure and/or a coupling-out structure of a diffractive optical waveguide, comprising:
s11, providing a substrate;
s12, carrying out localized air cluster corrosion treatment of time-sharing partition on the substrate based on expected grating depth distribution and difference requirements among different grating depths, and controlling the size of a beam spot and the moving step length so as to form a rugged surface profile at different positions of the first surface of the substrate;
s13, depositing a grating material layer on the first surface of the substrate, and carrying out planarization treatment on the top of the grating material layer so as to enable the top of the grating material layer to be flat; the thickness of the grating material layer is unevenly distributed, so that when the grating material layer is etched to form the grating structure, the depth of the grating structure changes, and the diffraction efficiency of the grating structure along the light propagation direction is gradually increased;
s14, forming a patterned mask layer on the top of the grating material layer;
s15, etching the grating material layer to the first surface by taking the patterned mask layer as a mask so as to form the grating structure on the substrate;
and S16, removing the patterned mask layer.
2. The method of fabricating a grating structure according to claim 1, wherein the step S12 specifically includes:
the method comprises the steps of processing a substrate by a particle beam in a localized air mass at different positions of the substrate based on an expected grating depth distribution and a difference requirement between different grating depths, and modulating the processing depths of the different positions of the first surface of the substrate by modulating energy and/or residence time of the particle beam corresponding to the particle beam at the different positions of the first surface of the substrate so as to form a rugged surface profile at the different positions of the first surface of the substrate.
3. The method of manufacturing a grating structure according to claim 2, wherein the size of the particle beam is smaller than the size of the pupil expanding structure and/or the coupling-out structure, and the size of the particle beam is larger than the grating period of the grating structure.
4. A method of manufacturing a grating structure according to claim 3, wherein the processing of the substrate by localized beam of particles in the air mass acting on different locations of the substrate comprises:
controlling the particle beam to move along at least two directions to perform time-sharing partition effect so as to treat areas corresponding to different positions of the pupil expanding structure and/or the coupling-out structure on the first surface of the substrate; the two directions are parallel to a plane in which the top of the layer of grating material is located.
5. A method of manufacturing a grating structure according to claim 1, wherein the undulating surface profile comprises a surface profile that varies stepwise in at least two directions, and wherein the thickness difference between adjacent steps is not more than 10%.
6. The method of claim 5, wherein the substrate further comprises a second surface opposite the first surface, a step surface in the step-like varying surface profile is parallel to the second surface, and the layer of grating material is formed on a surface of the step.
7. The method of claim 1, wherein the grating material layer comprises a plurality of grating material layers, and the refractive index of each grating material layer is different.
8. The method of claim 7, wherein the refractive index of each of the layers of grating material increases gradually in a direction away from the substrate.
9. A method of making a diffractive optical waveguide, comprising:
providing a substrate;
based on the expected grating depth distribution and the difference requirements among different grating depths, carrying out localized air cluster corrosion treatment on different positions of the substrate in a time-sharing partition mode, and controlling the size of beam spots and the moving step length to form a rugged surface profile at different positions at least in a pupil expansion area and/or a coupling-out area of the first surface of the substrate;
depositing a grating material layer on the first surface of the substrate, and carrying out planarization treatment on the top of the grating material layer so as to planarize the top of the grating material layer; the thickness of the grating material layer is unevenly distributed, so that when the grating material layer is etched to form a grating structure in the pupil expansion area and/or the coupling-out area, the depth change of the grating structure enables the diffraction efficiency of the grating structure to be gradually increased along the light propagation direction;
forming a patterned mask layer on top of the grating material layer;
etching the grating material layer to the first surface by taking the patterned mask layer as a mask so as to form the grating structure on the substrate;
and removing the patterned mask layer to obtain the diffraction optical waveguide.
10. The method of claim 9, wherein the shape of the pupil expansion region is a closed shape surrounded by a curve and/or a straight line, and the shape of the coupling-out region is a closed shape surrounded by a curve and/or a straight line.
CN202310451215.4A 2023-04-24 2023-04-24 Grating structure and manufacturing method of diffraction optical waveguide Pending CN116540340A (en)

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