Bit rate and pulse width dependence of four-wave mixing of short optical pulses in semiconductor optical amplifiers

We investigate the saturation properties of four-wave mixing of short optic al pulses in a semiconductor optical amplifier. By varying the gain of the optical amplifier, we find a strong dependence of both conversion efficienc y and signal-to-background ratio on pulse width and bit rate. In particular , the signal-to-background ratio can be optimized for a specific amplifier gain. This behavior, which is coherently described in experiment and theory , is attributed to the dynamics of the amplified spontaneous emission, whic h is the main source of noise in a semiconductor optical amplifier. (C) 199 9 Optical Society of America.