Photonic crystal quantum cascade lasers with improved threshold characteristics operating at room temperature

The authors have fabricated GaAs/Al0.45Ga0.55As quantum cascade lasers (QCLs) with two-dimensional photonic crystal (PhC) mirrors. The monolithically integrated PhC mirrors consist of a triangular lattice of similar to 14 mu m deeply etched semiconductor pillars. The PhC is designed to exhibit a photonic band gap for both the Gamma M and the Gamma K crystal orientation and provides reflectivities of > 80%. Compared to a reference laser with the same cavity length of 600 mu m but as-cleaved facets, the QCLs with Gamma M and Gamma K oriented PhCs show reductions of the threshold current by 34% and 30%, respectively. (c) 2006 American Institute of Physics.