We experimentally and theoretically demonstrate the SOA gain recovery time dependency on the probe signal wavelength and its optical power, in absence and in presence of the injection of a continuous wave (CW) high power assist light in the device. Experimental and numerical results show that for low probe powers and long wavelengths the gain recovery is significantly reduced. A theoretical evaluation of the transparency wavelength dependency 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 wavelengths effects on SOA gain recovery time is performed. Numerical calculations agree very well with experimental ones. As a result, the assist light injection reduces noticeably the SOA gain recovery time over a wide band of probe wavelengths.