Abstract
Optical feedback is a powerful technique to stabilise and narrow semi-conductor lasers. As a step forward for field deployable, ultra-stable yet tunable sources, we analyse and model the opto-mechanical design of a V-shaped cavity optical feedback (VCOF) reference cavity. We estimate the relative contributions of sources of external disturbance on the optical resonance frequency of the cavity, and ultimately define the minimal thermal and mechanical shielding requirements to face field conditions. We attest of the robustness of the developed system, and show that external sources of disturbance are only secondary contributors to the overall stability of the cavity. The suite of analytical tools developed in the process paves the way for lighter and more compact cavity designs, more adapted to field deployment.
Highlights
Infrared spectroscopy is a commonly used technique for rapid and accurate trace detection measurements in gas [1, 2]
We provide a description of the modelling approach, of the results compared to experimental values, as well as the implication for the use of such cavities in infrared spectroscopy for metrology and geosciences purposes
We were able to obtain the power spectral density of the changes in length of the cavity induced by the main contributors: for frequencies below 1 Hz, the thermo-mechanical processes [contributors (M1) and (m2)], and for frequencies above 1 Hz, the vibrations [contributor (M2)]
Summary
Infrared spectroscopy is a commonly used technique for rapid and accurate trace detection measurements in gas [1, 2]. As the measurements of gas species rely on measuring the areas, it is crucial to have a good sensitivity, as provided by Cavity RingDown Spectroscopy (CRDS) techniques [6], and a fine and stable frequency source [7]. The development of more powerful instrument (either in term of detectivity limit or of stability), is justified by the growing need for precise measurements: in the laboratories for fundamental physical properties determination [8, 9], and for field studies in geosciences [10, 11]. We provide a description of the modelling approach, of the results compared to experimental values, as well as the implication for the use of such cavities in infrared spectroscopy for metrology and geosciences purposes
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