Optical signal-to-noise ratio measurement in WDM networks using polarization extinction

Abstract

An optical signal-to-noise ratio measurement technique utilizing polarizaiion extinction has been tested in a back-to-back configuration and along a 940km fiber route between Germany and Austria. We discuss benefits and practical limitations of the technique.

A Robust Real-Time 100G Transceiver With Soft-Decision Forward Error Correction [Invited]

“…It was not possible to directly measure the OSNR at the receiver with conventional methods, due to ASE filtering at every ROADM and the fact that, if a channel is turned off at the transmit side, the commercial WDM system's control loops change the WSSs in all ROADMs to the block state for that channel. Therefore, the 100G PM-QPSK signal from the 100G transponder was replaced with a polarized, continuous-wave signal at the same wavelength and power, and the received OSNR was estimated using the polarization nulling technique [35].…”

Simplified approach to low‐cost multiparameter monitoring based on low frequency polarization modulation

“…Among the parameters to be monitored, one can mention the optical signal‐to‐noise ratio, differential group delay (DGD) and polarization mode dispersion (PMD), optical power, and the Q factor [1], ideally measured on a channel‐by‐channel basis. A number of techniques have been proposed and implemented to monitor subsets of these parameters, including inband OSNR, monitored by polarization extinction [2–4], and PMD [5, 6].…”

Novel OSNR Monitoring Technique in Dense WDM Systems using Inherently Generated CW Monitoring Channels

“…However, this method becomes insufficient in dense WDM systems where the channel side-bands are effectively hiding the noise level [2]. Methods have been developed to overcome this problem, and in [3][4][5] it have been reported how the accuracy of OSNR monitoring can be improved under such circumstances using either polarization extinction [3], polarization nulling [4] or digital signal processing [5].…”