Efficient optical modelling of VCSELs using a vector mode-matching method

Recent vertical-cavity surface-emitting lasers (VCSELs) include complex features, such as oxide apertures or intracavity index-guides, which complicate the electromagnetic modelling problem. Determining the optical characteristics of the cavity is essential to correctly interpret the physical behaviour of these devices. The authors have developed an efficient vector optical solver combining a mode-matching method and Krylov subspace techniques For a general VCSEL structure with cylindrical geometry. The solver generates accurate results for the cavity-mode profiles, resonant wavelengths, losses and threshold gain coefficients. Comparison with experimental data is shown. Scalar and vector modelling results are directly compared for the first time and the limits of the scalar approximation are investigated. It is found that the scalar approximation leads to large errors for small, strongly index-guiding apertures. The model is applied to both oxide-apertured and implant-apertured index-guided VCSEL structures