Modeling thermal effects and polarization competition in vertical-cavity surface-emitting lasers

Abstract

We analyze the influence of thermal effects on thepolarization-resolved light-current (LI) characteristics of verticalcavitysurface-emitting lasers (VCSELs). We use a model that is anextension of the spin-flip model incorporating material gain that isfrequency and temperature dependent, and a rate equation for thetemperature of the active region, which takes into account decayto a fixed substrate temperature, Joule heating and nonradiativerecombination heating. The model also incorporates the red shift forincreasing temperature of the gain curve and of the cavity resonance.The temperature sensitivity of the lasing threshold current is found tobe in good qualitative agreement with observations and with previousreports based on detailed microscopic models. The temperaturedependence of the polarization switching point, when the dominantpolarization turn off and the orthogonal polarization emerges, ischaracterized in terms of various model parameters, such as theroom-temperature gain-cavity offset, the subtracte temperature, andthe size of the active region.