| CPC G02B 6/0026 (2013.01) [G02B 6/4204 (2013.01); G03H 2001/0088 (2013.01)] | 26 Claims |
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1. An optical waveguide, comprising:
a waveguide substrate having a first surface and a second surface oppositely disposed for totally reflecting light entering the inside of the waveguide substrate and causing the light to propagate within the waveguide substrate through total internal reflection; and
at least one grating disposed in the waveguide substrate and located between and inclined with respect to the first surface and the second surface for transmitting and reflecting incident light or for transmitting and diffractively deflecting incident light, wherein the transmitted light is coupled into the waveguide substrate to propagate within the waveguide substrate through total internal reflection, and the reflected or diffractively deflected light is coupled out from the waveguide substrate,
wherein the grating is configured such that:
when incidence angles of the incident light on the grating are different, reflection efficiencies or diffraction deflection efficiencies of the grating are different,
the reflection efficiency when the incidence angle is less than a first angle and greater than a fourth angle is greater than the reflection efficiency when the incidence angle is greater than the first angle; or the diffraction deflection efficiency when the incidence angle is less than the first angle and greater than the fourth angle is greater than the diffraction deflection efficiency when the incidence angle is greater than the first angle, and
wherein the first angle is greater than the fourth angle.
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