Inverse synchronization in semiconductor laser diodes - art. no. 013805

The study of nonlinear dynamical systems is a subject of much interest, one application being in secure communication systems realized through the syn chronization of chaotic dynamical systems. In this paper optical coupling i s used to effect synchronization between two diode lasers in a master-slave configuration, and we study the effect of frequency detuning between the m aster and slave lasers on the character of the observed synchronization. Ex perimental conditions are found under which the synchronization plot (forme d by plotting the output power of the slave laser against that of the maste r at each instant in time) makes a transition from a positive gradient to a negative gradient. The appearance of such a negative gradient is a new phe nomenon, to our knowledge, which we term "inverse synchronization." A rate- equation model is proposed which accounts for light injection into the slav e laser, and which agrees with the experimental results. Using this model, we establish that inverse synchronization is caused by nonresonant coupling between the master and slave lasers.