Expand this Topic clickable element to expand a topic
Skip to content
Optica Publishing Group
  • CLEO/Europe and IQEC 2007 Conference Digest
  • (Optica Publishing Group, 2007),
  • paper CH4_1

Optical Vernier Spectrometer Broad band, high resolution, high sensitivity

Not Accessible

Your library or personal account may give you access

Abstract

Broad band cavity enhanced absorption spectroscopy methods have recently seen a renaissance [1, 2], when it was realized that the power throughput through such a resonator can be dramatically increased when using a coherent frequency comb as a light source instead of an incoherent (truly) broadband source. The resolution of this method was however limited by the spectrometer, recording the ring down signal and ignoring the high temporal coherence of the driving signal. It was already realized by the authors, that resolving the individual comb components could boost the resolution of the method from the limitation of usual spectral disperser techniques to the Hertz level that is provided by stabilized lasers. Combining broad band cavity enhanced absorption detection with a comb resolving broad band spectrometer in an efficient and unambiguous manner however proves challenging: a) combining the ring down method of [2] with a high resolution broad band echelle type spectrometer is not easily achieved as the second dimension of the CCD detector is required for both the streak camera and the echelle. b) the sample under investigation not only introduces absorbtion but also dispersion, rendering the matching between resonator mode frequencies and frequency comb imperfect so that non-ring-down analysis of the transmitted signal is hampered. Here we demonstrate an extension of the dispersion sensitive method as demonstrated in [3], that combines its phase sensitivity with comb mode resolution, pushing its resolution limitations down to laser line width. The basic idea is to detune the resonator with respect to the driving frequency comb such that the cavity mode frequency spacing is and integer fraction like 10/9th of the frequency comb repetition frequency. Like this, only every 10th mode of the driving frequency comb is transmitted at a single tuning of the cavity. These transmitted modes can now easily be resolved using a simple grating spectrometer. If the transmitted spectrum is now recorded as a function of the resonator tuning, cavity enhanced absorbtion and dispersion values can be recovered for each comb frequency. A proof of principle experiment (see Figure) provides clear comb mode resolution with a sample spacing of 1 GHz over a bandwidth of 4 THz. The demonstrated sensitivity is better than 10−6/cm Hz−1/2 with a resonator of finesse 3000 and a length of about 30 cm.

© 2007 IEEE

PDF Article
More Like This
A High Resolution Broad Spectral Range Spatial Heterodyne Spectrometer for UV Laboratory Astrophysics

J. Harlander, J. E. Lawler, F. L. Roesler, and Z. Labby
FWA3 Fourier Transform Spectroscopy (FTS) 2007

Doppler-limited multiplex sensitive spectroscopy with frequency combs

Julien Mandon, Guy Guelachvili, Frédéric Druon, Patrick Georges, and Nathalie Picqué
JSIII_4 International Quantum Electronics Conference (IQEC) 2007

An Ultra-High Resolution Volume Holographic Spectrometer

Majid Badieirostami, Omid Momtahan, Chao Ray Hsieh, Ali Adibi, and David J. Brady
FWH2 Frontiers in Optics (FiO) 2007

Select as filters


Select Topics Cancel
© Copyright 2024 | Optica Publishing Group. All Rights Reserved