Surface-emitting quantum cascade lasers with metallic photonic-crystal resonators

Abstract

Surface emitting photonic-crystal quantum cascade lasers operating at λ≈7.3 μm are demonstrated. The photonic crystal resonator is written solely on the top metallization layer. The mismatch between the modes supported by metallized and nonmetallized regions yields enough optical feedback to achieve laser action. The devices exhibit single-mode emission with a side mode suppression ratio of ≈20 dB, the wavelength is lithographically tunable across a range of almost 70 cm−1, and the radiation is emitted from the surface. The maximum operating temperature is 220 K. The divergence of the output beam, which is doughnut-shaped, is approximately 9°.