Effects of spatial hole burning on gain switching in vertical-cavity surface-emitting lasers

We present a numerical study of the effects of carrier diffusion and spatial hole-burning in vertical-cavity surface-emitting lasers under gain switching. Our model includes spatial and temporal dependences of both the optical field and the carrier density. Results show that spatial hole burning places a limit on the minimum achievable pulse width. We demonstrate that spatial hole-burning tan be avoided and shorter pulses can be obtained by using an appropriate pumping geometry. We also consider the case in which the laser operates simultaneously in two transverse modes and show that transverse-mode competition induced by spatial hole burning leads to period doubling and other interesting nonlinear behavior.