Third-order photonic-crystal distributed-feedback quantum cascade lasers

We demonstrate room-temperature operation of broad-area edge-emitting photonic-crystal distributed-feedback quantum cascade lasers at λ ∼ 4.6 μm. The lasers use a weak-index perturbed third-order photonic-crystal lattice to control the optical mode in the wafer plane. Utilizing this coupling mechanism, the near-diffraction-limited beam quality with a far-field profile normal to the facet can be obtained. Single-mode operation with a signal-to-noise ratio of about 20 dB is achieved in the temperature range of 85–290 K. The single-facet output power is above 1 W for a 55 μm × 2.5 mm laser bar at 85 K in pulsed mode.

► Third-order photonic-crystal lattice was used to control the optical mode of the quantum cascade lasers.
► The photonic-crystal structure was fabricated by holographic lithography.
► The near-diffraction-limited beam quality with a far-field profile peaked normal to the facet can be obtained.