Antimonide-based 2.3 μm photonic crystal coupled-cavity lasers for CH4

GaInAsSb/AlGaAsSb quantum wells lasers have been grown by molecular beam epitaxy and processed into ridge cavities coupled by an intracavity photonic crystal mirror. The lasers operate at room temperature in the continuous wave regime at 2.35 m. One of these devices was used as an excitation source on a methane sensor based on quartz-enhanced photoacoustic spectroscopy. A spectrophone, consisting of a quartz tuning fork and two steel microresonators, was used. A detection limit of 400 ppbv was achieved using second derivative wavelength modulation detection.