Patent ID: 9720147
Date: 2017-08-01
CPC Classifications: B29D,G02B,G03F

Claim:
1. A reflective diffraction grating comprising: a substrate; an ultraviolet (UV)-absorbing layer disposed over the substrate, and separate from the substrate, for absorbing light at a UV recording wavelength during holographic patterning, the UV-absorbing layer being: formed of a UV-absorbing dielectric material having an extinction coefficient of greater than about 0.025 at the UV recording wavelength, and having a thickness greater than 1.2 μm and less than 2 μm; a grating layer, disposed over the UV-absorbing layer, having a binary surface-relief pattern formed therein, wherein the binary surface-relief pattern includes ridges having rectangular or trapezoidal cross-sections separated by grooves; and a conforming reflective layer, disposed over the binary surface-relief pattern, forming a grating profile, the grating profile being associated with profile parameters, and the UV-absorbing dielectric material and the thickness of the UV-absorbing layer being selected such that particular patterns are suppressed during the holographic patterning.