Temperature Dependences of Metal-Clad Subwavelength Semiconductor Lasers (MCSELs): Geometric Invariance and the Spontaneous Emission Factor

We perform two analyses on temperature effects in Metal-Clad Subwavelength Semiconductor Lasers (MCSELs). Firstly, we analyze the temperature dependence of the threshold gain in the infinite waveguide approximation. We show that the dielectric layer of the semiconductor-dielectric-metal composite waveguide (CWG) becomes increasingly important as temperature increases. However, we further show that the optimal geometry of the CWG is nearly invariant with the temperature. Secondly, we relax the infinite waveguide assumption with the fully 3D finite element method, and analyze the temperature dependence of the spontaneous emission factor, β. We identify a cavity geometry that mitigates detuning between the dominant cavity mode and emission spectra. Ignoring coupling to freespace modes, we explain that the modified cavity may lead to a MCSEL with large β (~0.5) for all temperatures.