A scalar variational method for resonant modes of oxide-apertured vertical-cavity surface-emitting lasers

A scalar variational method for calculating the mode sizes and resonant wavelengths of the eigenmodes in oxide-apertured vertical-cavity surface-emitting lasers is presented. This method uses Hermite-Gaussian (TEMmp) functions to approximate the transverse-field variations of the eigenmodes. It is applicable to devices with circular, square, or rectangular apertures. Calculated results for the four lowest-order modes show that aperture size, thickness, and axial position are important factors in determining the blueshift in resonant wavelengths, wavelength separation between eigenmodes, and mode sizes. When the geometric symmetry is broken, as in rectangular-apertured devices, the degeneracy between the TEM01 and TEM10 is also lifted. For validation of the model presented, three vertical-cavity surface-emitting laser structures with different oxide thicknesses were grown and fabricated for this study. The resonant wavelength characteristics of near-square and rectangular devices were assessed. The theoretical results are found to agree well with the experimental observations. (C) 2000 American Institute of Physics. [S0021-8979(00)04201-8].