Optical waveguides

摘要

An optical waveguide (2) arranged to transmit light under total internal reflection has a first diffractive grating region (8) arranged to receive light and diffract the received light along the optical waveguide (2), an intermediate diffraction grating (10) optically coupled to the first diffractive grating region (8) arranged to expand received light in a first dimension and a second diffractive grating region (9) optically coupled to the intermediate diffraction grating (10) arranged to expand light in a second dimension, orthogonal to the first dimension and to output the light expanded in the first and second dimensions from the optical waveguide (2) by diffraction. The first and second diffractive grating regions (8,9) are fabricated as a common grating whereas the second grating is fabricated above the common grating in an area where the common grating is erased by a coating.

主权项

1. An optical waveguide including:
an optical substrate arranged to transmit light under total internal reflection; a first diffractive grating region associated with the optical substrate and arranged to receive light and to diffract the received light along the optical waveguide; an intermediate diffraction grating associated with the optical waveguide and optically coupled to the optical substrate and to the first diffractive grating region, arranged to receive light diffracted from the first diffractive grating region and to expand the received light in a first dimension by diffraction; and, a second diffractive grating region associated with the optical substrate and optically coupled to the intermediate diffraction grating, arranged to receive light expanded in the first dimension by the intermediate diffraction grating, to expand the received light in a second dimension orthogonal to the first dimension by diffraction and to output the light expanded in the first and second dimensions from the optical waveguide by diffraction, wherein the first diffractive grating region and the second diffractive grating region are diffractive regions of a common grating and the common grating and the intermediate diffraction grating are separate integers.