Semiconductor optical amplifier studies under optical injection at the transparency wavelength in copropagative configuration

We experimentally and theoretically demonstrate the semiconductor optical amplifier (SOA) gain recovery-time (RT) dependence on the probe signal wavelength and power when injecting a continuous-wave high-power assist light in the device. In our paper, pump, probe, and assist-light waves are all copropagative. Experimental and numerical results show that the gain RT is significantly reduced over a wideband of probe wavelengths due to the assist-light use. The reduction is more pronounced for low probe powers. A theoretical evaluation of the transparency-wavelength dependence on both the probe wavelength and power is presented. Then, a study on assist-light power effects on the SOA dynamics as well as pump- and probe-wavelength effects on SOA gain RT is performed.