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Updated: Jun 26, 2026

Infrared Degenerate Four-wave Mixing with Upconversion Detection for Quantitative Gas Sensing
Published on: March 22, 2019
High-resolution broadband (>100 cm-1) infrared heterodyne spectro-radiometry using an external cavity quantum cascade
Damien Weidmann1, Gerard Wysocki
1Space Science and Technology Department, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire, UK. damien.weidmann@stfc.ac.uk
Abstract:
Broadband thermal infrared heterodyne spectro-radiometry using an external cavity quantum cascade laser as a tunable local oscillator has been performed over a frequency range of more than 100 cm(-1) at a central frequency of 1190 cm(-1). Heterodyne spectro-radiometry is demonstrated for two local oscillator tuning modes: broadband tuning for transmission and emission spectroscopy of broadband absorbers (Freon 12), and broadband frequency selection in combination with fine continuous frequency tuning for high-resolution (0.021 cm(-1)) transmission spectroscopy (N(2)O). In each case concentration retrievals are performed and analyzed. The spectroradiometer noise level is demonstrated to be twenty two and eight times the fundamental shot-noise limit in the two scanning modes respectively.
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