Modeling thermal effects on the light vs. current characteristic of gain-guided vertical-cavity surface-emitting lasers

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Abstract
Heating effects on the light power vs. current characteristic of planar top-emitting vertical-cavity laser diodes are analyzed by thermal, optical and electrical modeling. The two-dimensional finite element thermal-electrical simulation considers the spatial current funneling in the top p-doped distributed Bragg reflector and a current density dependent resistivity of the hetero-barrier. Layered regions are described by anisotropic material parameters. Non-uniform refractive index temperature coefficients of the semiconductor materials are applied in the vertical optical modeling. The strongly inhomogeneous temperature distribution causes thermal increases of emission wavelength and reflectivity as well as decreases of threshold gain and external quantum efficiency with rising current. Finally, the calculated maximum light power is found to be decisively affected by the temperature coefficients of the refractive indices.