Patent ID: 9671534
Date: 2017-06-06
CPC Classifications: G02B,H01S

Claim:
1. An optical device for reflective diffraction of an incident light beam, comprising: a reflecting structure having a stack of thin dielectric layers made alternately of a first dielectric material and of a second dielectric material, the first dielectric material having an optical index lower than that of the second dielectric material, a protective structure deposited on a thin dielectric layer made of the first dielectric material of the stack of the reflecting structure, the protective structure including at least a first mixture layer formed of a homogenous mixture of the first and second dielectric materials, the optical index of the first mixture layer being higher than that of the first dielectric material; wherein the protective structure comprises exclusively said first mixture layer; and wherein a periodic arrangement of patterns is etched on a free surface of the said protective structure, in said mixture layer, so as to form a diffraction grating.