Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Instantaneous trace gas fingerprint with laser frequency combs

30.11.2009
Scientists at the MPQ record ultrasensitive absorption broadband spectra within tens of microseconds by combining cavity enhancement and frequency comb spectroscopy.

Trace gas spectroscopic detection has drawn much interest in recent years, as it both allows a better understanding of the molecular spectra of weak overtone transitions and in situ non-intrusive sensing of compounds at low concentration. However, recording a broadband spectrum within a very short measurement time and with high sensitivity remains a challenge.

At the Max Planck Institute of Quantum Optics, a team of scientists around Professor Theodor W. Hänsch and Doctor Nathalie Picqué in a cooperation [1] involving the Laboratoire de Photophysique Moléculaire du Centre National de la Recherche Scientifique (Orsay, France), the University of Tokyo (Chiba, Japan) and the Ludwig Maximilian's University (Munich, Germany) have implemented a new instrument, based on laser frequency combs, which holds much promise for such a breakthrough. (Nature Photonics, AOP, January 2010 DOI:10.1038/nphoton.2009.217)

The remarkable convergence between two separate fields, ultrafast optics and frequency metrology, has led to the precise control of the frequency spectrum produced by mode-locked lasers, which consists of a regular comb of sharp lines. The resulting optical frequency combs, pioneered by 2005 Nobel Prize laureate Professor Theodor W. Hänsch, have had tremendous impact on the various areas of precision measurement and extreme nonlinear optics. A growing list of applications includes molecular spectroscopy.

Here, the new instrument comes into play. All the equidistant modes of a first laser frequency comb are injected into a resonant passive high finesse cavity, which contains a gas sample. Inside the cavity the interaction length between the light and the sample is dramatically enlarged due to multiple reflections. This enhances the molecular absorption signal by several orders of magnitude. The light transmitted by the cavity exhibits a broad band spectrum of absorption lines, which needs to be analysed by a spectrometer: a second frequency comb, with a slightly detuned repetition frequency. The beat notes between pairs of lines from the two combs reveal the optical spectrum. This Fourier transform spectrometer without moving parts is one-million times faster than the scanning Michelson-based Fourier transform interferometer, which has been the dominating instrument in analytical sciences for decades. The cavity-enhanced dual-comb spectrometer described here has the potential to become a powerful tool for ultrasensitive spectroscopy without sacrificing high-resolution, spectral bandwidth, and high-speed.

A proof-of-principle experiment has been undertaken by Birgitta Bernhardt, with the help of Akira Ozawa and Patrick Jacquet, all graduate students. With Ytterbium-based fiber frequency combs emitting around 1040 nm, they succeeded for the first time in resolving the crowded weak overtone spectrum of ammonia, a molecule of planetological and environmental interests. Moreover the spectrum was recorded within only 18 microseconds and the achieved sensitivity is already 20-fold better, with a 100-fold shorter measurement time, than present state-of-the-art experiments. "As we are able to record such sensitive spectra every 20 microseconds, our technique exhibits an intriguing potential for the monitoring of chemical reactions or the spectroscopic sensing of dynamic single-events. Furthermore, we could extend our experimental concept to any region of the electromagnetic spectrum, in particular to the mid-infrared 'molecular fingerprint' region where no powerful real-time techniques are available at present. Here the implementation of the cavity-enhanced-dual-comb method would for instance allow sub-ppb minimum detectable concentrations for a variety of molecules of atmospheric relevance. This exhilarating perspective however still presents challenging issues", states Birgitta Bernhardt.

The field of trace gas sensing is presently advancing in many different directions ranging from biomedicine to environmental monitoring or analytical chemistry, plasma physics and laboratory astrophysics. The cavity-enhanced dual-comb spectroscopy technique might find many important applications for practical spectroscopy. (Olivia Meyer-Streng)

[1] The collaboration between the Max Planck Institute for Quantum Optics of the Max Planck Society and the Laboratoire de Photophysique Moléculaire du Centre National de la Recherche Scientifique is performed in the frame of the "European Laboratory for Frequency Comb Spectroscopy" European Associated Laboratory.

Original publication:
B. Bernhardt, A. Ozawa, P. Jacquet, M. Jacquey, Y. Kobayashi, T. Udem, R. Holzwarth, G. Guelachvili, T.W. Hänsch, N. Picqué,
Cavity-enhanced dual-comb spectroscopy,
Nature Photonics, Advance Online Publication, January 2010, doi:10.1038/ nphoton.2009.217
Contact:
Prof. Dr. Theodor W. Hänsch
Max Planck Institute of Quantum Optics
Hans Kopfermann strasse 1
85748 Garching
Phone: +4989 32905 712
Email: t.w.haensch@mpq.mpg.de
Dr. Nathalie Picqué
Max Planck Institute of Quantum Optics &
Centre National de la Recherche Scientifique
Phone: +4989 32905 290
Email: nathalie.picque@u-psud.fr
Mrs. Birgitta Bernhardt
Max Planck Institute of Quantum Optics
Phone: +4989 32905 295
Email: birgitta.bernhardt@mpq.mpg.de
Dr. Olivia Meyer-Streng
Max Planck Institute of Quantum Optics
Press & Public Relations
Tel.: +4989 32905 213
Fax: +4989 32905 200
E-Mail: olivia.meyer-streng@mpq.mpg.de

Dr. Olivia Meyer-Streng | Max-Planck-Institut
Further information:
http://www.mpq.mpg.de

More articles from Physics and Astronomy:

nachricht Quantum optics allows us to abandon expensive lasers in spectroscopy
22.11.2017 | Lomonosov Moscow State University

nachricht Nano-watch has steady hands
22.11.2017 | University of Vienna

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Corporate coworking as a driver of innovation

22.11.2017 | Business and Finance

PPPL scientists deliver new high-resolution diagnostic to national laser facility

22.11.2017 | Physics and Astronomy

Quantum optics allows us to abandon expensive lasers in spectroscopy

22.11.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>