Near infrared optical interference filters with improved transmission
US11372144B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 19, 2019 |
| Grant date | Jun 28, 2022 |
| Priority date | — |
| Expiry date | Aug 15, 2040 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B5/285
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
An interference filter includes a layers stack comprising a plurality of layers of at least: layers of amorphous hydrogenated silicon with added nitrogen (a-Si:H,N) and layers of one or more dielectric materials, such as SiO2, SiOx, SiOxNy, a dielectric material with a higher refractive index in the range 1.9 to 2.7 inclusive, or so forth. The interference filter is designed to have a passband center wavelength in the range 750-1000 nm inclusive. Added nitrogen in the a-Si:H,N layers provides improved transmission in the passband without a large decrease in refractive index observed in a-Si:H with comparable transmission. Layers of a dielectric material with a higher refractive index in the range 1.9 to 2.7 inclusive provide a smaller angle shift compared with a similar interference filter using SiO2 as the low index layers.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.