Optical method and system for measuring in-band crosstalk in Raman amplifiers

摘要

A method and system for measuring in-band crosstalk in an optical amplifier, such as a Raman amplifier, in which a modulated optical signal is generated using an input modulator. The extinction ratio of the input optical modulator is measured. The modulated optical signal is passed through the optical amplifier to obtain a first output optical signal, the power level of which is measured when the input modulator is in its off-state. The modulated optical signal is then attenuated by a factor equal to the extinction ratio of the input modulator to obtain an attenuated modulated optical signal which is passed through the optical amplifier to obtain a second output optical signal. The power level of the second output optical signal when the input modulator is in its on-state. The in-band crosstalk is calculated by subtracting the power level of the second output optical signal from the power level of the first output optical signal. The input and output modulators may be acousto-optic modulators. The power level, in each of a number of wavelength bands, may be measured by an optical spectrum analyzer. The input and output modulators are time synchronized to allow for measurements in the on- or off-states of the input modulator.