Effect of waveguide sidewall roughness on the threshold current density and slope efficiency of quantum cascade lasers
21 July 2008
We report on a study to determine the effect of waveguide sidewall roughness on quantum cascade (QC) laser performance using two two-wavelength heterogeneous QC laser structures, one with emission wavelengths of 7.0 mu m/11.2 mu m, and the other with 8.7 mu m/12.0 mu m. For the range of roughness standard deviation values from about 0.4 to 1.0 mu m, for which all four QC lasers were operating, the threshold current density increases by 12%-15% and the slope efficiency decreases by 30%-70% with stronger performance degradation for the shorter wavelength lasers, which is in agreement with a model based on Rayleigh scattering. (C) 2008 American Institute of Physics.