Reflective diffraction gratings employing efficiency enhancement or etch barrier layers
US10802184B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 28, 2015 |
| Grant date | Oct 13, 2020 |
| Priority date | — |
| Expiry date | Apr 14, 2036 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B2005/1804
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A diffraction grating comprises a substrate (with index nsub) with a surface facing an optical medium (with index nmed<nsub), a dielectric or semiconductor layer of thickness t on the substrate surface (with index nL≠nsub), and a set of diffractive elements on the layer (with index nR≠nmed). The diffractive elements comprise a set of ridges protruding into the optical medium, which fills trenches between the ridges, and are characterized by a spacing Λ, a width d, and a height h. Over an operational wavelength range, λ/2nsub<Λ<λ/(nsub+nmed). An optical signal incident on the diffractive elements from within the substrate at an incidence angle exceeding the critical angle, nsub, nmed, nL, nR, Λ, d, h, and t result in wavelength-dependent, first-order diffraction efficiency of the grating greater than a prescribed level over the operational wavelength range for both s- and p-polarized optical signals.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.