Influence of the retarded response on an ultrafast nonlinear optofluidic fiber coupler

We demonstrate by numerical simulations of coupled generalized nonlinear Schrödinger equations that the input pulse duration as well as the retarded material response have a crucial impact on the properties of an ultrafast nonlinear optofluidic fiber coupler. This device is composed of two waveguides in close vicinity embedded in a photonic crystal fiber which are filled with a highly nonlinear liquid. We show that in particular the critical peak power above which the coupling between the waveguides is suppressed increases dramatically for short input pulses and long characteristic response times of the liquid. We establish a simple model which describes these effects with high accuracy.