Optical Phase Synchronization by Injection of Common Broadband Low-Coherent Light

We demonstrate experimentally and numerically that, by injecting common broadband optical noise into two uncoupled lasers, the phases of the respective laser oscillations can be successfully synchronized. Experimental observation of the resulting phase dynamics is achieved using a heterodyne detection method. The present phase synchronization differs from the synchronization induced by coherent light signals or narrow band optical noise in the sense that it occurs without any frequency locking to the injection light. Moreover, it is revealed that there is an optimal intensity of the injection light that maximizes the quality of the phase synchronization. These results can open new perspectives for understanding and functional utilization of the laser phase dynamics.