Analysis of optical field propagation and open resonator modes in the context of vertical cavity surface emitting lasers

Evolution of the VCSEL structure over the years has resulted in a device geometry that is difficult to analyse/model using traditional modal analysis. Present day (e.g., oxide aperture) VCSELs resemble cylindrical (open) optical resonators that have essentially diffracting optical field propagation determined by the oxide aperture and the equivalent locations of the finite sized end mirrors. This paper presents a quasi-analytic function expansion method based on the use of a set of Laguerre-Gauss (LG) functions, combined with the numerical collocation method, to achieve a versatile, effective and efficient scheme for computing the optical fields in inhomogeneous open (VCSEL) resonators.