Improvement of the input power dynamic range for wavelength converters based on cross-gain modulation employing a probe power control loop

A technique for improving the input power dynamic range of wavelength converters based on cross-gain modulation in a semiconductor optical amplifier is presented. By experimentally investigating the effect of pump and probe powers on the operating performance in terms of power penalty for a conventional wavelength converter, we show that the optimal performance depends on the ratio of pump and probe powers coupled into the semiconductor optical amplifier in a certain input power range. Based upon the experimental result, a wavelength converter with a wide dynamic range has been proposed, in which the probe power is automatically adjusted to have the power proportional to the pump power. We show that a dynamic range of >20 dB is achievable for a 2.5 Gbit/s signal at a 2-dB penalty.