Broadband calibration-free complex refractive index spectroscopy in a cavity using a comb-based fourier transform spectrometer

Johanssson, Alexandra C.

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https://hdl.handle.net/2142/100648 Copy

Description

Title

Broadband calibration-free complex refractive index spectroscopy in a cavity using a comb-based fourier transform spectrometer

Author(s)

Johanssson, Alexandra C.

Contributor(s)

• Filipsson, Anna
• Rutkowski, Lucile
• Axner, Ove
• Zhao, Gang
• Hausmaninger, Thomas
• Foltynowicz, Aleksandra

Issue Date

2018-06-19

Keyword(s)

Mini-symposium: Frequency-Comb Spectroscopy

Abstract

Fabry-Perot cavities provide high sensitivity to molecular absorption and dispersion since the mode position, width and amplitude are modified in the vicinity of molecular transitions. Moreover, the mode shift and broadening are directly proportional to the real and imaginary parts of the molecular complex index of refraction, but independent of cavity parameters, such as the cavity length and mirror reflectivity, which reduces the influence of systematic errors. Previous demonstrations of cavity enhanced complex refractive index spectroscopy were based on continuous wave lasers and limited to individual absorption linesa,b . Here we use an Er:fiber frequency-comb-based Fourier transform spectrometer with sub-nominal resolutionc,d to measure a broadband transmission spectrum of a cavity filled with 1% of CO2 in N2 at 750 Torr. From Lorentzian fits to each cavity mode we retrieve mode positions and widths, which in turn yield high precision dispersion and absorption spectra of the entire 3ν1+ν3 absorption band of CO2 at 1.6 µm. Fits to these spectra yield line intensities that agree to within 0.6%. Thus comb-based Fourier transform spectroscopy enables broadband cavity mode characterization and calibration-free determination of both the real and imaginary parts of entire molecular absorption bands with high accuracy and precision.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/100648

DOI

10.15278/isms.2018.TG08

Copyright and License Information

Copyright 2018 Alexandra C. Johanssson

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