Pump-wavelength dependence of FWM performance in semiconductor optical amplifiers

We report on experimental investigation of the dependence on pump-wavelength of efficiency and signal to background ratio of a wavelength converter based on four-wave mixing in a semiconductor optical amplifier (SOA). The signal wavelength has been varied over a 60-nm range at fixed signal-converted detuning. Both efficiency and background level increase by moving the operation wavelength toward bandgap. Nevertheless, we observe a variation of the signal to background ratio of only 2 dB in a 40-nm range. A qualitative interpretation of the results is presented.