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 Measured for the first time: Direction of light waves changed by quantum effect
24.05.2017 | Vienna University of Technology

nachricht Physicists discover mechanism behind granular capillary effect
24.05.2017 | University of Cologne

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: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

Physicists discover mechanism behind granular capillary effect

24.05.2017 | Physics and Astronomy

Measured for the first time: Direction of light waves changed by quantum effect

24.05.2017 | Physics and Astronomy

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>