In-band OSNR monitoring using fibre optical parametric amplifier

An in-band optical signal-to-noise ratio (OSNR) monitor based on an optical parametric amplifier is presented. This is achieved using the nonlinear relationship between the input signal power and the power in a new wave generated by cascaded four-wave mixing. The average output power of the new wave is dependent on the OSNR of the input signal. Experiments on the OSNR monitor show a good match to simulations.