Fast all-optical flip-flop memory exploiting the electric field nonlinearity of coherent laser amplifiers

The coherent nonlinear feedback in an integrated optical flip-flop is studied in order to demonstrate device applications of laser amplifiers operated above the laser threshold. The nonlinear feedback is provided by the stabilizing fields of the laser amplifiers, interfering with coherent optical reference fields. In both stable states of the flip-flop, the nonlinear feedback allows the laser amplifiers to maintain an ever present photon population in the laser modes and to have an approximately constant carrier population. This enables faster response (switching times below 25 ps are reached in this work)than in conventional active optical flip-flop structures. The operation of the flip-flop is studied using a rate equation model accounting for the carrier densities and the complex electric fields in the different cavity modes of the laser amplifiers.