Operational design on high-speed semiconductor optical amplifier with assist light for application to wavelength converters using cross-phase modulation

Using the newly developed time-dependent transfer matrix method with nonlinear effects, we analyzed the characteristics of cross-phase modulation (XPM), cross-gain modulation and gain recovery time of a semiconductor optical amplifier (SOA) with an assist light injection, which is introduced to speed up the gain recovery of the SOA. Particularly for the application to high-speed wavelength converters using XPM with an interferometer structure where pi-phase change is required, various parameters such as SOA lengths, wavelengths and powers of injected lights, and their propagation directions are designed via numerical simulation. Discussions concerning the conditions of an SOA structure and the parameters of injected lights for high-speed operation are described to show the potential of fast gain recovery with a response time as low as 25 ps.