A time-domain computer simulator of the nonlinear response ofsemiconductor optical amplifiers

摘要

We present a computer simulator of semiconductor opticalnamplifiers. The nonlinear input-output response of the device isncharacterized in terms of a complex gain, representing the accumulatedngain and wavevector change of the propagating field across the activenwaveguide. We account for the gain saturation induced by stimulatednrecombination and by the perturbation of the carrier quasi-equilibriumndistribution within the bands. A rigorous elimination of the spatialncoordinate allows us to reduce the description of the amplifier dynamicsnto the solution of a set of ordinary differential equation for thencomplex gain. If the waveguide internal loss is negligible, the spatialninhomogeneity of the complex gain is implicitly yet exactly taken intonaccount by the reduced model. The accuracy of the reduced model is thensame for models based on the direct solution of the set of partialndifferential equations describing the interaction between the opticalnfield and the active semiconductor waveguide, but the model isncomputationally much simpler. To preserve the input-outputncharacteristics of the model, we include the amplified spontaneousnemission noise in the device description by an equivalent signal appliednto the device input and amplified by the saturated gain. At the expensenof a minor increase of the program complexity, the waveguide internalnloss may also be included. We report on the comparison between thenoutput of the simulator and the results of four-wave mixing experimentsnin various pump-signal configurations. Good agreement is obtained