Tunable filter system with backreflection reference
US6473234B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Feb 28, 2001 |
| Grant date | Oct 29, 2002 |
| Priority date | — |
| Expiry date | Mar 31, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B6/4286
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A tunable filter system comprises a signal source providing a WDM having multiple channels, or other signal requiring spectral analysis, within a spectral signal band. A reference signal source is also provided that generates a reference signal with spectral features, such as narrow spectral lines, that are located within a spectral reference band. A tunable filter functions as a band pass filter in transmission and a notch filter in reflection. It is controlled to filter both the reference signal and the WDM signal. A transmission detector is provided to detect the signal transmission through the tunable filter and a return detector is provided to detect the signal that is returned from the filter. Embodiments of the invention rely on a characteristic of a class of tunable filters, such as Fabry Perot etalons, in which light that is not transmitted through the filter is reflected. Thus, while the tunable filter appears as a band pass filter in transmission, it functions as a notch filter in reflection.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.