Patent ID: 8320722

Claim:
An optical grating configured for light of a wavelength, the optical grating comprising: a top cladding; a core having a plurality of discrete ridges spaced apart by a nonlinear pitch, the light traversing the top cladding before the core and having a plurality of angles of incidence with the core, the nonlinear pitch being larger for a larger angle of incidence of the plurality of angles of incidence, the core further including a first optically transparent layer, a stop layer on the first optically transparent layer and a second optically transparent layer on the stop layer, the first optically transparent layer being continuous and including a material, the stop layer being configured to be invisible to the light, and the second optically transparent layer including the material and the plurality of discrete ridges; a bottom cladding, the core residing between the bottom cladding and the top cladding; and a mirror, the bottom cladding residing between the core and the mirror.