HIGH RESOLUTION OPTICAL PERFORMANCE MONITOR FOR DWDM SYSTEM

摘要

An apparatus for measuring the optical signal-to-noise ratio of an optical system is adapted to function in single channel or in multi-channel wavelength division multiplexed optical communication systems. An optical signal spectrum and a center frequency characterize the optical signals. A narrow-band notch filter (122), realized by an in-fibre Bragg grating, is utilized to remove a component of the signal so the remaining signal can be measured. When multiple channels are present, a bandpass filter (124) is used to select the part of the multiplexed signal to be measured. The filters can be tunable (134). Two detectors (128, 130) are utilized with the power in the channel being measured by a low-gain detector (128) and the power in the noise being measured by a high-gain detector (130). A processor (132) receives the detector outputs, calculates the optical signal-to-noise ratio and controls the tunable components.