Self-Consistent Modelling of Diffraction in VCSEL Bragg Stacks

Vertical cavity curface emitting lasers (VCSELs) are the subject of much research at present, given their circular output beam and the ease with which they can be fabricated into two-dimensional arrays [1]. Very high mirror reflectivities, often as high as 99.9% [2], are required, due to the short gain region. Since reflectivities are difficult to measure experimentally, it is necessary to know whether these high relectivities can be attained in theory. Usually it is assumed that the reflectivity of a Bragg mirror is given by the plane wave value, ignoring diffraction effects at the cavity/mirror interface.