Circuit for monitoring optical signals
US6262822A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 13, 1998 |
| Grant date | Jul 17, 2001 |
| Priority date | — |
| Expiry date | May 13, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B10/07955
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
The present invention relates to a circuit for monitoring optical signals in a multiple channel system. A tunable band pass filter receives and input signal comprising multiple channels each having a different wavelength and predetermined channel spacing. Output from the tunable filter is directed to a second filter having a periodic response with wavelength, such as an etalon. The response is designed to block wavelengths of light corresponding to the channels, permitting noise in the inter-channel space to be measured by a detector. A reference circuit launches light from a broad band source through a Bragg grating into the tunable filter. The Bragg grating reflects a known reference wavelength. Light which passes from the reference source through the tunable filter is also passed through the second filter to a detector. When a notch is detected by the reference detector, the tunable filter is known to be tuned to the reference wavelength. A comparison to the signal output at the first detector is used to correlate the position of the notch and the location of any inter-channel noise. A third filter, also preferably a fixed etalon, has a periodic response which matches the channe…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.