Method and apparatus for monitoring wavelength multiplexed optical signals
US5969834A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 3, 1997 |
| Grant date | Oct 19, 1999 |
| Priority date | — |
| Expiry date | Sep 3, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B10/071
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
One method of determining the signal to noise ratio of an optical signal models the noise floor based on amplified spontaneous emission (ASE) which is accumulated along the link. The ASE wavelength dependence is represented by a known mathematical function with a limited number of parameters. The parameters of this function are derived from measurements of the noise floor at a limited number of points by computational best fit means. A number of fiber grating filters at wavelengths between ITU allocated wavelengths are used to sample the optical noise and reflect the light back. An optical circulator is used to direct the reflected ASE light to an optical switch which allows the detector to select between transmitted and reflected light. The signal transmitted through the switch is monitored by a scanning filter with the appropriate resolution to resolve the signal or noise peaks. A first scan of the transmitted peaks is carried out and the signal is digitized and stored. A second scan of the reflected noise is carried out and digitized. A microcomputer computes the peak values and wavelengths, calibrates the wavelength scale from the known grating wavelengths, recomputes the ASE s…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.