Uniform incoupler for conical incidence
AssigneeInterDigital Madison Patent Holdings, SAS
InventorsValter Drazic, Oksana Shramkova, Bobin Varghese, Valerie Allie
Life of this patent
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Abstract
In example embodiments, a waveguide display apparatus includes a waveguide comprising a substrate, a plurality of diffractive grating elements on the waveguide, and at least two coating layers on the waveguide between the substrate and the diffractive grating elements. The grating elements may be elements of a diffractive in-coupler. Some embodiments include three coating layers, with a middle layer having a refractive index greater than that of the substrate, the middle layer being between two layers having a refractive index lower than that of the substrate. Some embodiments further include a fourth coating layer.
Claims16
An apparatus comprising:
- a waveguide comprising a substrate having a substrate refractive index;
- at least three coating layers on the waveguide over the substrate, the coating layers comprising a first coating layer, a second coating layer, and a third coating layer, the third coating layer being in contact with the substrate, and the second coating layer being between the first coating layer and the third coating layer,
- wherein:
- the first coating layer has a first refractive index lower than the substrate refractive index;
- the second coating layer has a second refractive index higher than the substrate refractive index;
- and
- the third coating layer has a third refractive index lower than the substrate refractive index;
- at least one phase-modifying layer at least between the grating elements and the first coating layer or between the first and second coating layers, the phase-modifying layer having a thickness of 5-10 nm and a refractive index greater than the second refractive index, the at least one phase-modifying layer having a thickness of 5-10 nm and a refractive index greater than the second refractive index;
- and
- a plurality of diffractive grating elements over the coating layers.
A method comprising:
- applying at least three coating layers over a surface of a waveguide substrate having a substrate refractive index;
- wherein:
- the coating layers comprise a first coating layer, a second coating layer, and a third coating layer, the third coating layer being in contact with the substrate, and the second coating layer being between the first coating layer and the third coating layer, and
- the first coating layer has a first refractive index lower than the substrate refractive index, the second coating layer has a second refractive index higher than the substrate refractive index, and the third coating layer has a third refractive index lower than the substrate refractive index;
- applying at least one phase-modifying layer at least between the grating elements and the first coating layer or between the first and second coating layers, the phase-modifying layer having a thickness of 5-10 nm and a refractive index greater than the second refractive index, the at least one phase-modifying layer having a thickness of 5-10 nm and a refractive index greater than the second refractive index;
- and
- applying a plurality of diffractive grating elements over the coating layers.
Dependencies are inferred from the claim text.