An adaptive stepsize controlled solver for the dynamic WDM semiconductor optical amplifier response

A time-domain solver for the response of a Semiconductor Optical Amplifier (SOA) relying on multigrid numerical techniques and a wideband steady state material gain coefficient is presented for the first time. Multigrid techniques enable the efficient solution of implicit time discretization schemes for the associated system of coupled differential equations, namely the carrier rate equation in the time domain and the signal amplification in the spatial domain, which in turn enable accuracy-instead of stability-restricted time-discretization of the signals. This allows lifting off the limitations of an equidistant spatio-temporal grid for the representation of the incoming signals adopted by traditional explicit SOA models, releasing an adaptive stepsize controlled solver for the dynamic SOA response with dense time-sampling under a rapidly varying SOA signal output and scarce time-sampling when negligible changes are observed.