Optical signal level control apparatus
US7394951B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 13, 2003 |
| Grant date | Jul 1, 2008 |
| Priority date | — |
| Expiry date | Oct 18, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04J14/0201
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
In an optical signal level control apparatus used in a WDM system, the amount of circuitry per wavelength is reduced. Optical power level is detected on the output side of a variable optical attenuator, and the amount of attenuation in the variable optical attenuator is adjusted so that the output level becomes equal to a constant value L1. At this time, if the detected level is lower than a threshold value Th0 or Th-d, it is determined that a signal off condition has occurred, and the amount of attenuation is set to a constant value A1. The amount of attenuation, A1, is chosen to be sufficiently larger than the amount of attenuation used in the output level constant control but small enough to be able to detect the restoration of the signal. When the amount of attenuation is being held at the constant value A1, if the output level is restored to a level higher than the threshold value Th0 or Th1 (Th1<Th-d), the output constant control is resumed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.