Mechanism for the determination of power and optical signal-to-noise-ratio values in a DWDM system by using noise suppression
Original Publication Date: 2002-Apr-01
Included in the Prior Art Database: 2003-Jul-23
Bernhard Kessler: AUTHOR [+3]
The procedure for calculation of the optical signal-to- noise ratio (OSNR) and the signal power values in optical spectrum analysers (OSA) was not accurate enough for the demands of the development and integration of TransXpress Infinity systems. Espe- cially for the control and adjustment of the optical link, the OSNR and power values have to be adjusted with least possible errors to ensure optimum optical performance. For the OSNR calculation, the determi- nation of the spectrum's noise floor is necessary.
Mechanism for the determinationof power and optical signal-to-noise-ratio values in a DWDM sys-tem by using noise suppression
Information / Kommunikation
Idee: Bernhard Kessler, München;
Simone Ebert, München;Alvaro Carvalho, P-Coimbra
The procedure for calculation of the optical signal-to-noise ratio (OSNR) and the signal power values inoptical spectrum analysers (OSA) was not accurateenough for the demands of the development andintegration of TransXpress Infinity systems. Espe-cially for the control and adjustment of the opticallink, the OSNR and power values have to be adjustedwith least possible errors to ensure optimum opticalperformance. For the OSNR calculation, the determi-nation of the spectrum's noise floor is necessary.
The recently designed WDM systems have a smallchannel grid and are loaded with high bitrate signals.So the available noise floor between two peaks isvery small. The minimum between two speaks can bea solution for a point of the optical noise floor. Onthe other hand the WDM aren't always full loaded orevenly distributed. If there is a large distance be-tween two peaks and the noise floor isn't flat, thedetermining of the minimum won't give enough ac-curacy. In this case the better solution is to determinethe noise floor at a fix distance from the middle ofthe peak. But this distance depends on the dynamiccharacteristics of the OSA. See also item 2.)
The signal characteristic is measured at monitoringpoints on the optical amplifier units. The opticalpower level on the monitoring points is less than 20dB. If a high accuracy is required, the sensitivity ofthe OSA must be selected high. By increasing thesensitivity of some OSA's the sweep time will in-crease from 10s to 60s. This will be very time con-suming.
Non-linear optical effects may also cause a wrongdetermination of OSNR and power value. Due tothese errors,...