Improved power and far-field pattern of surface-emitting quantum cascade lasers with strain compensation to operate at 4.3 μm

Abstract We fabricated surface-emitting quantum cascade lasers with photonic crystal resonators whose active layers were strain-compensated InGaAs/AlInAs multiple wells to operate at 4.3 μ m. tested two kinds of square-lattice crystals consisting circular and pentagonal InGaAs cylinders as a unit structure. examined their output power far-field pattern find that both them improved by lowering the photonic-crystal symmetry achieve high extraction efficiency. The maximum was 50 mW 77 K single peak divergence angle smaller than 1° for cylinder In addition, we attributed lasing mode B 2 -symmetric (quadrupole) eigenstate on Γ point structure observing polarization dependence comparing it calculations k · p perturbation method.