Photoluminescence studies of optical properties of VECSEL active region under high excitation conditions

Abstract

In this paper we demonstrate results of photoluminescence studies of the active region of vertical-external-cavity surface-emitting lasers. The investigated structure has been designed for lasing at 980 nm. The gain medium consists of six In0.18Ga0.82 As quantum wells embedded in a microcavity enclosed from the substrate side by distributed Bragg reflectors formed by 27 pairs of GaAs/AlAs and from the surface side by a l/2 thick AlGaAs window layer. The quantum well emission collected from the chip surface is modified by the resonance of this cavity. However, unequivocal information about optical properties of the active region can be provided by the photoluminescence signal measured from a cleaved edge of the epitaxial wafer. The density of excitation influences the spectral position of emission from the quantum wells forming the active region. On the basis of our studies of edge emitted PL signal we have determined the dependence between the intensity of the quantum well emission and the density of excitation power. The optimal excitation conditions of investigated structure have been also determined.