THERMAL EFFECTS ON THE THRESHOLD OF VERTICAL-CAVITY SURFACE-EMITTING LASERS - FIRST-ORDER AND 2ND-ORDER PHASE-TRANSITIONS

We investigate the threshold behavior of vertical-cavity surface-emitt ing lasers (VCSEL's) by solving the set of coupled equations for carri er density, field amplitude, and plasma and lattice temperatures. We s how that, because of plasma heating and lattice heating, the threshold of VCSEL's can be continuous or discontinuous with bistability betwee n lasing and nonlasing states (correspondingly second- or first-order phase transition), depending on the relative position of the cavity fr equency to the gain bandwidth and on the ambient (substrate) temperatu re of the device.