Multiheterodyne Spectroscopy Using Interband Cascade Lasers
Journal Article - Open Access
NAVAL RESEARCH LAB WASHINGTON DC WASHINGTON United States
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While midinfrared radiation can be used to identify and quantify numerous chemical species, contemporary broadband midinfrared spectroscopic systems are often hindered by large footprints, moving parts, and high power consumption. In this work, we demonstrate multiheterodyne spectroscopy MHS using interband cascade lasers, which combines broadband spectral coverage with high spectral resolution and energy-efficient operation. The lasers generate up to 30 mW of continuous-wave optical power while consuming 0.5 W of electrical power. A computational phase and timing correction algorithm is used to obtain kHz linewidths of the multiheterodyne beat notes and up to 30 dB improvement in signal-to-noise ratio. The versatility of the multiheterodyne technique is demonstrated by performing both rapidly swept absorption and dispersion spectroscopic assessments of low-pressure ethylene C2H4 acquired by extracting a single beat note from the multiheterodyne signal, as well as broadband MHS of methane CH4 acquired with all available beat notes with microsecond temporal resolution and an instantaneous optical bandwidth of similar to 240 GHz. The technology shows excellent potential for portable and high-resolution solid-state spectroscopic chemical sensors operating in the midinfrared.
- Atomic and Molecular Physics and Spectroscopy
- Lasers and Masers