Pump-power dependence of transparency characteristics in semiconductor optical amplifiers

A numerical investigation is performed of the characteristics of the pump-power dependent transparency carrier density of semiconductor optical amplifiers (SOAs) in pump-probe configurations. The simulations show good agreement with published experimental measurements. It is found that both gain compression due to two-photon absorption (TPA) and TPA carrier generation are crucial in determining the behavior of SOAs at transparency. In particular, a novel technique for significantly reducing the pump-power dependence of the transparency carrier density is proposed. Calculations also indicate that, by using negative frequency detuned probe and pump pulses, SOAs with fixed-transparency carrier densities can be obtained for a large pump energy range.