Apodization of optical filters with multiple exposures of photosensitive media
US6694075B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 30, 1999 |
| Grant date | Feb 17, 2004 |
| Priority date | — |
| Expiry date | Jun 30, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B6/02123
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Filter gratings are formed in optical waveguides having photosensitive cores by exposing the cores to actinic radiation in the form of interfering beams having peak intensities that are relatively displaced along an optical axis of the waveguides. Each of the interfering beams has a single-lobed intensity profile and a degree of spatial coherence required to achieve a desired fringe contrast between the two relatively displaced beams. Index modulations in the photosensitive core match the illumination (interference) pattern of the radiation. The relative displacement of the interfering beams reduces side lobes of the gratings' spectral responses by leveling the average refractive index of the index modulations. A second exposure with the two beams but without the beams' interference effects further levels the average refractive index.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.