Patent ID: 6813021
Filing Date: 2004-11-02
Classification: G01J

Abstract:
A method for monitoring an optical signal-to-noise ratio (OSNR) using a polarization-nulling method, comprising the steps of:(a) linearly polarizing an arbitrarily polarized optical signal including an unpolarized ASE noise; (b) separating the optical signal and the ASE noise from the linearly polarized optical signal including the unpolarized ASE noise to measure a power of the optical signal and a power of the ASE noise included in a bandwidth of an optical signal; and (c) obtaining the optical signal-to-noise ratio (OSNR) using the measured optical signal power and ASE noise power, wherein the step (a) comprises the step of: (a1) allowing the polarization of the linearly polarized optical signal including the unpolarized ASE noise to be continuously changed; and wherein the step (b) comprises the steps of: (a2) measuring a minimum power and a maximum power of the signal outputted from a linear polarizer; and (a3) measuring the power of the optical signal and the power of the ASE noise included in the bandwidth of the optical signal from the measured minimum power and maximum power of the signal outputted from the linear polarizer.