CN220064417U - Grating structure, pupil expanding structure, coupling-out structure, and diffraction optical waveguide - Google Patents
Grating structure, pupil expanding structure, coupling-out structure, and diffraction optical waveguide Download PDFInfo
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- CN220064417U CN220064417U CN202320950940.1U CN202320950940U CN220064417U CN 220064417 U CN220064417 U CN 220064417U CN 202320950940 U CN202320950940 U CN 202320950940U CN 220064417 U CN220064417 U CN 220064417U
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- 230000003287 optical effect Effects 0.000 title claims abstract description 8
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- 239000000463 material Substances 0.000 claims description 28
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- 230000002911 mydriatic effect Effects 0.000 claims 2
- 238000000034 method Methods 0.000 description 27
- 238000005530 etching Methods 0.000 description 20
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- Diffracting Gratings Or Hologram Optical Elements (AREA)
Abstract
The utility model provides a grating structure, comprising: a substrate; the first surface of the substrate is provided with a rough surface profile which is processed by localized air mass corrosion at different positions; a plurality of grating units; formed on the first surface of the substrate; the top parts of the grating units are flat, the top parts are all positioned on the same horizontal plane, and the thicknesses of the grating units on the first surface are different; the depth of each grating element varies such that the diffraction efficiency of the grating element increases gradually along the direction of light propagation. The technical scheme solves the problem of modulating the diffraction efficiency of the light by the grating structure. The utility model also provides a pupil expanding structure, a coupling-out structure and a diffraction optical waveguide.
Description
Technical Field
The utility model relates to the field of diffraction waveguides, in particular to a grating structure, a pupil expanding structure, a coupling-out structure and a diffraction optical waveguide.
Background
In the traditional diffraction waveguide, in order to make the light beams emitted by the coupling-out grating or the pupil expansion grating more uniform, grating units with different depths are usually arranged, the manufacturing process difficulty of grating structures with different depths is larger, multiple etching is often needed, the manufacturing process is complex, the consistency of different grating structures prepared by the same imprinting master is poor based on the refractive index problem of grating materials, the grating structures with depth modulation in the prior art are usually formed on the surface of a substrate with flat surface and uniform thickness, the process repeatability is poor, and the difficulty of mask patterning at the top of a grating material layer is larger.
Disclosure of Invention
The utility model provides a grating structure, a pupil expanding structure, a coupling-out structure and a diffraction optical waveguide, which are used for solving the problem of modulating the diffraction efficiency of light by the grating structure, ensuring the consistency of grating structures of different etching process batches and realizing the stability of the grating and the waveguide structure.
According to a first aspect of the present utility model there is provided a grating structure comprising:
a substrate; the first surface of the substrate is provided with a rugged surface profile formed by localized air mass corrosion treatment in a time-sharing partition at different positions;
a plurality of grating units; formed on the first surface of the substrate; the top parts of the grating units are flat, the top parts are all positioned on the same horizontal plane, and the thicknesses of the grating units on the first surface are different; the depth of each grating element varies such that the diffraction efficiency of the grating element increases gradually along the direction of light propagation.
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, siO 2 High refractive index glass (HRI), resin, etc.; the said processGas finger C 4 F 8 、NF 3 、He、O 2 Ar, etc.
Optionally, the surface profile includes a profile that forms a step-like change in at least two directions, and the thickness difference between adjacent steps is not more than 10% or 5% or 1%.
Optionally, the substrate further comprises a second surface opposite to the first surface, the surface of the step in the step-like varying profile being parallel to the second surface, the grating units being formed on the surface of the step.
Optionally, each grating unit includes a plurality of grating material layers, and refractive indexes of adjacent grating material layers are different.
Optionally, the refractive index of several of the layers of grating material increases in a direction away from the substrate.
Optionally, the grating units are in a straight tooth structure or an inclined tooth structure.
Optionally, the thickness of each grating unit on the first surface is 10nm-100nm.
According to a second aspect of the present utility model there is provided a pupil expanding structure comprising a grating structure according to any of the first aspects of the present utility model.
According to a third aspect of the present utility model there is provided an out-coupling structure comprising a grating structure according to any one of the first aspects of the present utility model.
According to a fourth aspect of the present utility model there is provided a diffractive optical waveguide comprising a pupil expanding structure according to the second aspect of the present utility model and/or a coupling-out structure according to the third aspect of the present utility model.
According to the grating structure provided by the utility model, the grating units with the flat top are formed on the first surface of the substrate, and the different positions of the first surface of the substrate are the uneven surface contours, so that the thicknesses of the grating units on the first surface are different, and the diffraction efficiency of the grating units along the light propagation direction is gradually increased by controlling the thickness variation of the grating units on the first surface, so that the purpose of adjusting the light propagation uniformity is achieved. Therefore, the utility model provides a new technical scheme, creatively provides a technical route for forming the grating unit on the surface of the rugged substrate, has fewer etching times, solves the problem of modulating the diffraction efficiency of the light by the grating structure, further realizes the modulation of uniformity, ensures the consistency of the grating structure of different process batches based on different substrates and has fewer etching times, and realizes the stability of the grating and the waveguide structure.
Compared with the prior art, under the condition of reasonably selecting the etching selection ratio between the substrate and the grating material layer, the structure and the process are simple, the etching times can be reduced on the premise of ensuring 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.
Drawings
In order to more clearly illustrate the embodiments of the utility model 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 utility model, 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 schematic diagram of a grating structure according to an embodiment of the present utility model;
FIG. 2 is a schematic diagram of another grating structure according to an embodiment of the present utility model;
reference numerals illustrate:
101-a substrate;
102-raster unit.
Detailed Description
The following description of the embodiments of the present utility model 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 utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.
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 utility model 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 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, in the prior art, there are generally the following technical methods:
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 materials 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. The prior art has the following defects:
for the above process method 1, the imprinting glue material is used as the grating material, and the imprinting process is limited by the refractive index of the imprinting glue material (usually, the refractive index is higher and only about 1.9), so that it is difficult to realize high diffraction efficiency with different wavelengths and large field angles.
For the above process 2, gray scale lithography is used, and the controllability is low. The process of forming the sacrificial layer of ideal non-uniform thickness is difficult.
For the above-mentioned process method 3, a plurality of etching processes are required, and an additional etching stop layer is required; meanwhile, the problem of low controllability exists, the etching results of the same process parameters in different processes are different, an additional etching stop layer is needed, and meanwhile, when a mask layer is formed on the surface of the grating material layer and patterning is carried out, the patterning process is difficult and the operation is inconvenient because of the uneven surface.
In view of this, the inventors of the present utility model have skillfully used a semiconductor localized air-cluster etching process to perform time-division and zone-division trimming on different positions of the surface of a substrate, based on the beam spot size of a particle beam, control the beam spot size and the movement step length, and perform zone-division etching by using the chemical action of gas, so that the thickness of a flat surface is non-uniform, a grating material layer with a flat top is formed on the flat surface, and a patterned mask layer is formed on the surface of the grating material layer, and then a depth-modulated grating structure can be formed by one etching, thereby forming grating units with non-uniform thickness on the surface of the substrate.
According to the technical scheme provided by the utility model, the localized air-cluster corrosion can realize the separate processing of time-sharing and area-division, the process principle and the process are substantially different from those of the conventional etching process, the energy of the localized air-cluster corrosion in the processing process is kept constant, the substrate processing time of different areas is controlled based on the grating depth requirement, the reproducible uneven different substrates can be obtained, the grating material is not limited by the imprinting adhesive material any more, and the grating material can be used as a grating material layer by depositing the high refractive index material.
Therefore, the technical scheme provided by the utility model creatively provides a grating structure with grating units formed on the surface of the substrate with flat surface and non-uniform thickness.
The technical scheme of the utility model 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 utility model, there is provided a grating structure including:
a substrate 101 (201); the first surface of the substrate 101 (201) has a rugged surface profile treated by localized air-cluster etching at different locations; the localized air-cluster corrosion treatment is determined based on the expected grating depth distribution and the difference requirements between different grating depths; localized air-cluster etching refers to performing time-division partitioning treatment by taking the beam spot size of a particle beam as a reference and performing partitioning etching by controlling the beam spot size and the moving step length through the chemical action of gas.
The substrate refers to Si, siO 2 High refractive index glass (HRI), resin, etc.; the gas means C 4 F 8 、NF 3 、He、O 2 Ar, etc. A number of raster units 102 (202); formed on a first surface of the substrate 101 (201); wherein the tops of the grating units 102 (202) are flat, the tops are all positioned on the same horizontal plane, and the thicknesses of the grating units 102 (202) on the first surface are different; the depth of each grating element 102 (202) varies such that the diffraction efficiency of the grating element 102 (202) increases gradually along the direction of light propagation.
The utility model provides a novel grating structure for realizing grating depth modulation, in the grating structure, grating units 102 (202) with flat tops are formed on a first surface of a substrate 101 (201), different positions of the first surface of the substrate 101 (201) are uneven surface profiles, so that the thicknesses of the grating units 102 (202) on the first surface are different, and further, the depth change of each grating unit 102 (202) can meet the requirement that the diffraction efficiency of the grating units 102 (202) along the light propagation direction is gradually increased by controlling specific parameters of the uneven surface profiles, thereby achieving the purpose of adjusting the uniformity of light beams propagated by the grating structure. The particle beam in localized air-cluster corrosion is controlled to move along at least two directions for time-sharing and partitioning action so as to treat the areas corresponding to different positions of the first surface to form a surface profile.
Therefore, the technical scheme provided by the utility model creatively provides a technical route for forming the grating unit 102 (202) on the rugged surface, solves the problem of modulating the diffraction efficiency of the grating structure on light, and further realizes the modulation on uniformity.
In one embodiment, the surface profile comprises a profile that varies stepwise in at least two directions, and the thickness of two adjacent steps differs by no more than 10%. In other embodiments, the thickness difference between two adjacent steps may be not greater than 5% or even not greater than 1%, depending on the actual performance requirements.
In one embodiment, the substrate 101 (201) further includes a second surface opposite the first surface, the surfaces of the steps in the step-like varying profile being parallel to the second surface, and the grating units 102 (202) are each formed on a surface of a step. Therefore, the bottoms of the grating units are parallel to the second surface of the substrate, and the bottoms of the gaps between the grating units are parallel to the second surface of the substrate, so that the light rays can be transmitted in the substrate in a normal total reflection mode.
In one embodiment, each grating unit 102 (202) includes several layers of grating material, and the refractive indices of adjacent layers of grating material are different.
In one embodiment, the refractive index of the layers of grating material increases in a direction away from the substrate 101 (201).
In one embodiment, the plurality of grating elements 102 (202) are in a straight-tooth configuration or a skewed-tooth configuration. Wherein the angle of the helical teeth is controllable. Such as 20 degrees to 40 degrees, which is the angle from the normal of the first surface.
In one embodiment, each grating element 102 (202) has a thickness on the first surface of 10nm-100nm.
Next, according to an embodiment of the present utility model, there is also provided a pupil expanding structure including the grating structure of any of the preceding embodiments of the present utility model.
In addition, according to an embodiment of the present utility model, there is also provided a coupling-out structure comprising the grating structure of any of the preceding embodiments of the present utility model.
Finally, according to an embodiment of the present utility model, there is also provided a diffractive optical waveguide comprising the pupil expanding structure of the preceding embodiment of the present utility model and/or the coupling-out structure of the preceding embodiment of the present utility model.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present utility model, and not for limiting the same; although the utility model 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 utility model.
Claims (10)
1. A grating structure, comprising:
a substrate; the first surface of the substrate is provided with a rugged surface profile formed by localized air mass corrosion treatment in a time-sharing partition at different positions;
a plurality of grating units; formed on the first surface of the substrate; the top parts of the grating units are flat, the top parts are all positioned on the same horizontal plane, and the thicknesses of the grating units on the first surface are different; the depth of each grating element varies such that the diffraction efficiency of the grating element increases gradually along the direction of light propagation.
2. The grating structure of claim 1, wherein the surface profile comprises a profile that varies stepwise in at least two directions, and wherein the thickness difference between adjacent steps is no greater than 10% or 5% or 1%.
3. The grating structure of claim 2, wherein the substrate further comprises a second surface opposite the first surface, the surface of the steps in the step-like varying profile being parallel to the second surface, the grating elements each being formed on a surface of the step.
4. The grating structure of claim 1, wherein each grating unit comprises several layers of grating material, and the refractive indices of adjacent layers of grating material are different.
5. The grating structure of claim 4, wherein the refractive index of the layers of grating material increases in a direction away from the substrate.
6. The grating structure according to any one of claims 1-5, wherein a number of the grating elements are in a straight or skewed tooth configuration.
7. The grating structure of any one of claims 1-5, wherein each grating element has a thickness on the first surface of 10nm-100nm.
8. A mydriatic structure comprising a grating structure according to any one of claims 1-7.
9. A coupling-out structure comprising a grating structure according to any one of claims 1-7.
10. A diffractive optical waveguide comprising a mydriatic structure according to claim 8 and/or a coupling-out structure according to claim 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320950940.1U CN220064417U (en) | 2023-04-24 | 2023-04-24 | Grating structure, pupil expanding structure, coupling-out structure, and diffraction optical waveguide |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320950940.1U CN220064417U (en) | 2023-04-24 | 2023-04-24 | Grating structure, pupil expanding structure, coupling-out structure, and diffraction optical waveguide |
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| Publication Number | Publication Date |
|---|---|
| CN220064417U true CN220064417U (en) | 2023-11-21 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202320950940.1U Active CN220064417U (en) | 2023-04-24 | 2023-04-24 | Grating structure, pupil expanding structure, coupling-out structure, and diffraction optical waveguide |
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- 2023-04-24 CN CN202320950940.1U patent/CN220064417U/en active Active
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