The response of an optical system to external injection of light is a very important topic in photonics. Freetwm can be used to study the optical response of active devices subjected to arbitrary forms of optical injections. Here we exemplify the case of a ring laser which can operate into a bistable unidirectional regime and may be used as an optical latch. A sufficiently intense light injection can trigger a reversal of the direction of emission, see for instance [5,7].
|On the left, one can observe the dynamical response of the ring submitted to a 1 ns quasi-square optical pulse. The black filling represents actually the carrier wave frequency of the square pulse. Upon releasing the injection the direction of emission persists, after some transient relaxation oscillations where the intensity and the carrier reservoir reach equilibrium.|
The initial condition for the right panels is given by the final state of the time evolution on the left panels. Such states can be conveniently saved and loaded in binary mat files allowing for easy parametric studies.