umu.sePublications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Cavity-Enhanced Continuous-Filtering Vernier Spectroscopy at 3.3 mu m using a Femtosecond Optical Parametric Oscillator
Umeå University, Faculty of Science and Technology, Department of Physics.
Umeå University, Faculty of Science and Technology, Department of Physics.
Umeå University, Faculty of Science and Technology, Department of Physics.
Show others and affiliations
2017 (English)In: 2017 CONFERENCE ON LASERS AND ELECTRO-OPTICS EUROPE & EUROPEAN QUANTUM ELECTRONICS CONFERENCE (CLEO/EUROPE-EQEC), IEEE , 2017, p. CH_2_2-Conference paper, Published paper (Refereed)
Abstract [en]

Optical frequency comb spectroscopy in the mid-infrared fingerprint region combines broad spectral bandwidth with high detection sensitivity and allows simultaneous detection of trace amounts of many molecular species. We have recently demonstrated a continuous-filtering Vernier spectrometer based on a mid-infrared optical frequency comb and an enhancement cavity for fast and sensitive detection of CH4 [1]. Here we present an improved, fully automatized and frequency calibrated continuous-filtering Vernier spectrometer, schematically shown in Fig. 1(a). The comb source is a doubly resonant optical parametric oscillator (DROPO) based on an orientation-patterned GaAs crystal synchronously pumped by a Tm:fiber femtosecond laser (125 MHz repetition rate, frep). The signal comb (3.1–3.4 µm, 30 mW) is mode matched to a 60-cm long Vernier enhancement cavity with a finesse of ~350 at 3.25 μm, placed in an enclosure that can be filled with the gas sample. The output mirror is attached to a PZT and mounted on a translation stage. When the cavity free spectral range is perfectly matched to twice the frep (250 MHz) every other signal comb mode is transmitted through the cavity. By detuning the cavity length from this perfect match position the cavity resonances act as a filter and transmit groups of comb modes called Vernier orders [2]. A diffraction grating mounted on a galvo-scanner separates these orders after the cavity and the chosen order is sent to the detection system. The Vernier order is tuned across the signal comb spectrum by scanning the cavity length (at 20 Hz) and the grating is rotated synchronously to fix the order in space and allow acquisition of the entire spectrum in 25 ms. Any residual mismatch between the cavity length scan and the grating rotation is compensated by a feedback loop acting on the frep of the pump laser and the PZT of the Vernier cavity [2]. A Fabry-Perot etalon is used for frequency calibration of the spectrometer. Figure 1(b) shows in black the normalized transmission spectrum of a sample containing 5.0 ppm CH4 and 160 ppm water. The red and blue curves show the corresponding fit of the Vernier spectrum [3] of CH4 and water, respectively, calculated using Voigt profiles, line parameters from the HITRAN database, and the experimentally determined cavity finesse. The figure of merit of the spectrometer is 1×10−9cm−1 Hz−1∕2 per spectral element and multiline fitting yields minimum detectable concentration of CH4 of 2 ppb in 25 ms, translating into 400 ppt Hz−1∕2 Since the spectrum of the signal comb covers the fundamental C-H stretch transitions we expect low detection limits for other hydrocarbons as well. In conclusion, mid-infrared comb-based continuous-filtering Vernier spectroscopy allows fast and highly sensitive measurement of broadband absorption spectra using a robust and compact detection system.

Place, publisher, year, edition, pages
IEEE , 2017. p. CH_2_2-
National Category
Atom and Molecular Physics and Optics
Identifiers
URN: urn:nbn:se:umu:diva-155053ISI: 000432564600616ISBN: 978-1-5090-6736-7 (print)OAI: oai:DiVA.org:umu-155053DiVA, id: diva2:1275863
Conference
2017 European Conference on Lasers and Electro-Optics and European Quantum Electronics Conference, Munich Germany, 25–29 June 2017
Available from: 2019-01-07 Created: 2019-01-07 Last updated: 2019-01-07Bibliographically approved

Open Access in DiVA

No full text in DiVA

Other links

https://www.osapublishing.org/abstract.cfm?uri=cleo_europe-2017-CH_2_2&origin=search

Authority records BETA

Khodabakhsh, AmirRutkowski, LucileJohansson, Alexandra C.Soboń, GrzegorzFoltynowicz, Aleksandra

Search in DiVA

By author/editor
Khodabakhsh, AmirRutkowski, LucileJohansson, Alexandra C.Soboń, GrzegorzFoltynowicz, Aleksandra
By organisation
Department of Physics
Atom and Molecular Physics and Optics

Search outside of DiVA

GoogleGoogle Scholar

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 57 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf