Photoreflectance line shape symmetry and quantum-well ground-state excitonenergy in vertical-cavity surface-emitting laser structures

We report photoreflectance studies on the coupling between the Fabry-Perot cavity mode (CM) and the quantum well (QW) ground-state excitonic feature i n vertical-cavity surface-emitting laser structures. Changes in the symmetr y of the CM-QW spectral feature occur when the angle of incidence of the pr obe beam is altered. Using detailed simulations, we explain how this is rel ated to an unusual reversal of the roles of the Seraphin coefficients and Q W dielectric function, in determining the line shape. Our study suggests a way to find the exciton energy, in situations where a distinct QW feature i s not seen because of large broadening of the QW dielectric function combin ed with high reflectivity of Bragg mirrors and relatively narrow CM width. (C) 2001 American Institute of Physics.