Composite grating and manufacturing method thereof, diffraction optical waveguide, and electronic device
A composite grating includes a first relief structure and a second relief structure, the first relief structure includes a plurality of first slits, the second relief structure includes a plurality of second slits, the second relief structure is stacked on a light incident side of the first relief structure, the second slit faces away from the first relief structure, a surface of the first relief structure that faces away from the second relief structure is a reference plane, and an included angle between a projection, on the reference plane, of an extension direction of the first slit and a projection, on the reference plane, of an extension direction of the second slit is 10 degrees to 90 degrees.
1 . A composite grating, comprising:
a first relief structure defining a plurality of first slits; and
a second relief structure defining a plurality of second slits, wherein the second relief structure is stacked on a light incident side of the first relief structure, a widest part of each second slit is a side of the respective second slit that faces away from the first relief structure, a surface of the first relief structure that faces away from the second relief structure is a reference plane, wherein an included angle between a projection, on the reference plane, of an extension direction of a first slit of the plurality of first slits and a projection, on the reference plane, of an extension direction of a second slit of the plurality of second slits is 45 degrees to 60 degrees, the extension direction of the first slit is parallel to the reference plane, a profile of the first slit is symmetric along the extension direction of the first slit, the extension direction of the second slit is parallel to the reference plane, and a profile of the second slit is symmetric along the extension direction of the second slit.
2 . The composite grating according to claim 1 , wherein the second relief structure is partially embedded in the plurality of first slits.
3 . The composite grating according to claim 2 , wherein a refractive index of the first relief structure and a refractive index of the second relief structure are between 1.5 and 2.8, and the refractive index of the first relief structure is greater than the refractive index of the second relief structure.
4 . The composite grating according to claim 1 , wherein the composite grating further comprises an intermediate layer, wherein the intermediate layer is disposed between the first relief structure and the second relief structure, a refractive index of the first relief structure and a refractive index of the second relief structure are between 1.5 and 2.8, and a refractive index of the intermediate layer is less than the refractive index of the first relief structure.
5 . The composite grating according to claim 1 , wherein the first relief structure and the second relief structure each are an asymmetric grating.
6 . The composite grating according to claim 5 , wherein the first relief structure is a blazed grating or a slanted grating; or the second relief structure is a blazed grating or a slanted grating.
7 . The composite grating according to claim 1 , wherein a material of the first relief structure is nano-imprint-lithography resist or titanium dioxide; and/or a material of the second relief structure is nano-imprint-lithography resist or titanium dioxide.
8 . The composite grating according to claim 1 , wherein the composite grating further comprises an auxiliary layer, and the auxiliary layer is disposed on a side of the first relief structure that faces away from the second relief structure.
9 . The composite grating according to claim 1 , wherein the composite grating further comprises a substrate, and the substrate is located on the side of the first relief structure that faces away from the second relief structure.
10 . The composite grating according to claim 1 , wherein the composite grating further comprises a third relief structure, and the third relief structure is disposed on a side of the second relief structure that faces away from the first relief structure.
11 . A diffraction optical waveguide, comprising:
a waveguide base; and
a composite grating, wherein the composite grating is installed on a surface of the waveguide base and forms an in-coupling grating and/or an out-coupling grating of the waveguide base, and the composite grating comprises:
a first relief structure defining a plurality of first slits; and
a second relief structure defining a plurality of second slits, wherein the second relief structure is stacked on a light incident side of the first relief structure, a widest part of each second slit is on a side of the respective second slit that faces away from the first relief structure, a surface of the first relief structure that faces away from the second relief structure is a reference plane, wherein an included angle between a projection, on the reference plane, of an extension direction of a first slit of the plurality of first slits and a projection, on the reference plane, of an extension direction of a second slit of the plurality of second slits is 45 degrees to 60 degrees, the extension direction of the first slit is parallel to the reference plane, a profile of the first slit is symmetric along the extension direction of the first slit, the extension direction of the second slit is parallel to the reference plane, and a profile of the second slit is symmetric along the extension direction of the second slit.
12 . The diffraction optical waveguide according to claim 11 , wherein the second relief structure is partially embedded in the plurality of first slits.
13 . The diffraction optical waveguide according to claim 12 , wherein a refractive index of the first relief structure and a refractive index of the second relief structure are between 1.5 and 2.8, and the refractive index of the first relief structure is greater than the refractive index of the second relief structure.
14 . The diffraction optical waveguide according to claim 11 , wherein the composite grating further comprises an intermediate layer, wherein the intermediate layer is disposed between the first relief structure and the second relief structure, a refractive index of the first relief structure and a refractive index of the second relief structure are between 1.5 and 2.8, and a refractive index of the intermediate layer is less than the refractive index of the first relief structure.
15 . The diffraction optical waveguide according to claim 11 , wherein the first relief structure and the second relief structure each are an asymmetric grating.
16 . The diffraction optical waveguide according to claim 15 , wherein the first relief structure is a blazed grating or a slanted grating; and/or the second relief structure is a blazed grating or a slanted grating.
17 . The diffraction optical waveguide according to claim 11 , wherein a material of the first relief structure is nano-imprint-lithography resist or titanium dioxide; or a material of the second relief structure is nano-imprint-lithography resist or titanium dioxide.
18 . The diffraction optical waveguide according to claim 11 , wherein the composite grating further comprises an auxiliary layer, the auxiliary layer is disposed on a side of the first relief structure that faces away from the second relief structure.
19 . The composite grating according to claim 6 , wherein the first relief structure is a blazed grating or a slanted grating, and the second relief structure is a blazed grating or a slanted grating.
20 . The diffraction optical waveguide according to claim 17 , wherein a material of the first relief structure is nano-imprint-lithography resist or titanium dioxide, and a material of the second relief structure is nano-imprint-lithography resist or titanium dioxide.