Effects of transverse-mode competition on the injection dynamics of vertical-cavity surface-emitting lasers

We investigate theoretically the static and dynamic characteristics of an optically injected vertical-cavity surface-emitting laser (VCSEL), under both single-and two-mode operation. Our model includes the spatial dependence of both the carrier density and the optical field. We find that within the locking range, a two-mode VCSEL can be forced to operate in a single transverse mode under appropriate conditions. Outside the locking range, the VCSEL shows a rich variety of nonlinear dynamics. Results show that the static and dynamic behaviours depend strongly on the frequency detuning, the injection power and the strength of the intermodal coupling induced by spatial hole burning. In particular, strong intermodal coupling can reduce the sensitivity of the VCSEL toward external injection, in terms of both static (locking) and dynamic (nonlocking) behaviours.