Tunable optical filter
US5481402A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 22, 1994 |
| Grant date | Jan 2, 1996 |
| Priority date | — |
| Expiry date | Feb 22, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B6/2793
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An tunable optical filter of the kind used, for example, in wavelength-division multiplexing (WDM) optical communication systems and tunable source applications, has an interference filter element which is pivotable to adjust the operating wavelength of the filter. In order to reduce polarization dependency as the angle of the interference filter element changes, the light beam to be filtered is passed through the filter element twice, the second time with its polarization state shifted, specifically orthogonal, relative to the polarization state during the first pass. As a result, polarization dependent effects are equalized. The optical filter comprises a pivotally mounted filter element, an input optical fiber for directing a light beam to be filtered through the filter element in a first direction with a first polarization state, optical elements for rotating the polarization state of the filtered light beam and returning the light beam through the filter element (10) a second time, and an output optical fiber for receiving the light beam following passage of the light beam though the filter element the second time. The optical elements may comprise a reflector for reflecting a…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.