Patent ID: 8687982
Filing Date: 2014-04-01
Classification: H04B

Abstract:
1. An Optical Signal to Noise Ratio (OSNR) measuring device comprising: an input port to which a signal light is given; a wavelength filter which is optically coupled to the input port, includes a passband, and selectively takes out an optical component corresponding to a signal optical wavelength to be measured from the signal light; a delay interferometer which branches a light output from the wavelength filter and delays one of the branched lights with respect to the other branched light and in which the branched lights are made to interfere with each other; a photodetector which detects a power of a delay interference light output from the delay interferometer; and an OSNR calculation circuit which calculates, based on a bandwidth of a passband of the wavelength filter and the power of the delay interference light detected by the photodetector, an optical signal to noise ratio (OSNR) of a signal optical wavelength to be measured, the OSNR being calculated according to the following equation wherein Psig is power of the signal light, Pase is power of the Amplified Spontaneous Emission (ASE), P 2 is an average power of one of the branched lights, P 1 is an average power of the other of the branched lights, t is a ratio of an optical delay amount, and B is the bandwidth.