ANALYSIS OF MICROCAVITY VCSEL LASING MODES USING A FULL-VECTOR WEIGHTED INDEX METHOD

In this paper; we present a semi-analytic full-vector method for calcu lating the spatial profile, optical confinement factor, resonant frequ ency, absorption lass, and mirror loss of lasing modes in cylindricall y symmetric microcavity vertical-cavity surface-emitting lasers (VCSEL 's). It can be shown that this method gives the best separable approxi mation for the electric and magnetic vector potentials. Our technique can model the entire VCSEL structure and can treat complex media. We a pply the method to etched-post and oxide-apertured VCSEL's designed fo r 980-mm emission and find a blueshift in cavity resonance as the cavi ty radius shrinks. We also find a minimum optical cavity radius below which radially bound lasing modes cannot be supported. This radius dep ends on the device geometry and lies between 0.5 and 1 mu m for the de vices studied, Once this model is augmented to include diffraction los ses-the dominant loss mechanism for conventional small aperture lasers -it will provide a complete picture of lasing eigenmodes in microcavit y VCSEL's.