A Wide Study of Gain Transparency Wavelength Evolution in Semiconductor Optical Amplifiers

We investigate by numerical calculations the evolution of the gain transparency wavelength lambda_tr of a semiconductor optical amplifier (SOA) over a wide range of the optical signal power, wavelength, and the SOA bias current. We show that the most critical parameter to control is the input signal power. Our results demonstrated that for a low input signal power, lambda_tr is the same for all the signal wavelengths. A trade-off over a 30 nm range of HB wavelength in function of the injected signal parameters (wavelength, power and gain) is necessary to an optimized improvement of the SOA performance by the holding beam (HB) injection.