Effects of incomplete light extinction in frequency-agile, rapid scanning spectroscopy

D. A. Long; S. Wójtewicz; J. T. Hodges

doi:10.1117/12.2016056

29 May 2013 Effects of incomplete light extinction in frequency-agile, rapid scanning spectroscopy

D. A. Long, S. Wójtewicz, J. T. Hodges

Proceedings Volume 8726, Next-Generation Spectroscopic Technologies VI; 87260O (2013) https://doi.org/10.1117/12.2016056
Event: SPIE Defense, Security, and Sensing, 2013, Baltimore, Maryland, United States

Abstract

The effect of finite beam extinction ratio on the precision and accuracy of cavity ring-down decay time constant measurements was examined using the frequency-agile, rapid scanning, cavity ring-down spectroscopy (FARS-CRDS) technique. This new approach to CRDS uses a waveguide-based electro-optic phase modulator (EOM) to provide a laser beam extinction ratio as high as 80 dB: a value that is ≈30 dB greater than that typically achieved with acousto-optic-modulator- based beam switches. We find that the observed measurement precision scales inversely with extinction ratio, such that an EOM enables measurement of the cavity ring-down decay time with a relative precision of ≈8×10^-5. We demonstrate that insufficient extinction can be the dominant cause of statistical uncertainty for extinction ratios below 60 dB. Furthermore, insufficient extinction can result in non-exponential decays, which cause systematic measurement biases in cavity losses and absorption.

Citation Download Citation

D. A. Long, S. Wójtewicz, and J. T. Hodges "Effects of incomplete light extinction in frequency-agile, rapid scanning spectroscopy", Proc. SPIE 8726, Next-Generation Spectroscopic Technologies VI, 87260O (29 May 2013); https://doi.org/10.1117/12.2016056

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