Balanced-detection interferometric cavity-assisted photothermal spectroscopy via collimating fiber-array integration

• DOI: 10.1016/j.snb.2024.135766
• Publication Date: 2024-04-05T22:50:21Z
• Authors: Giulia Malvicini; Johannes P. Waclawek; Davide Pinto; Harald Moser; Simone Iadanza; Kamil Gradkowski; Liam O’Faolain; Bernhard Lendl
• Keywords: Collimated light

This work reports on the implementation of a fiber-array with attached microlenses in balanced-detection Interferometric Cavity-Assisted Photothermal Spectroscopy (ICAPS) scheme, enabling highly compact probe laser beam path. The sample and reference were coupled into 1-mm spaced Fabry-Perot interferometer parallel separation only 1.25 mm. A quantum cascade was used to induce photo-thermal waves, which detected via beam. realize balanced detection, allowing for significant noise reduction. sensor's metrological figures merit evaluated by detection nitric oxide. For targeted absorption band centered at 1900.08 cm-1 1 σ minimum limit 64 ppbv achieved 1-second integration time. performance corresponds normalized equivalent 5.7 ×10-8 W Hz-1/2.