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

摘要

The authors have fabricated GaAs/Al_(0.45)Ga_(0.55)As quantum cascade lasers (QCLs) with two-dimensional photonic crystal (PhC) mirrors. The monolithically integrated PhC mirrors consist of a triangular lattice of ～14 μm deeply etched semiconductor pillars. The PhC is designed to exhibit a photonic band gap for both the ΓM and the ΓK crystal orientation and provides reflectivities of > 80%. Compared to a reference laser with the same cavity length of 600 μm but as-cleaved facets, the QCLs with ΓM and ΓK oriented PhCs show reductions of the threshold current by 34% and 30%, respectively.