Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists build first 'frequency comb' to display visible 'teeth'

02.11.2009
Finally, an optical frequency comb that visibly lives up to its name.

Scientists at the University of Konstanz in Germany and the National Institute of Standards and Technology (NIST) in the United States have built the first optical frequency comb—a tool for precisely measuring different frequencies of visible light—that actually looks like a comb.

As described in the Oct. 30 issue of Science,* the "teeth" of the new frequency comb are separated enough that when viewed with a simple optical system—a grating and microscope—the human eye can see each of the approximately 50,000 teeth spanning the visible color spectrum from red to blue. A frequency comb with such well-separated, visibly distinct teeth will be an important tool for a wide range of applications in astronomy, communications and many other areas.

A basis for the 2005 Nobel Prize in physics, frequency combs are now commonplace in research laboratories and next-generation atomic clocks. But until now, comb teeth have been so closely spaced that they were distinguishable only with specialized equipment and great effort, and the light never looked like the evenly striped pattern of the namesake comb to the human eye.

Each tooth of the comb is a different frequency, or color (although the human eye can't distinguish the very small color differences between nearby teeth). A frequency comb can be used like a ruler to measure the light emitted by lasers, atoms, stars or other objects with extraordinarily high precision. Other frequency combs with finer spacing are highly useful tools, but the new comb with more visibly separated teeth will be more effective in many applications such as calibrating astronomical instruments.

The new comb is produced by a dime-sized laser that generates super-fast, super-short pulses of high-power light containing tens of thousands of different frequencies. As in any frequency comb, the properties of the light over time are converted to tick marks or teeth, with each tooth representing a progressively higher number of oscillations of light waves per unit of time. The shorter the pulses of laser light, the broader the range of frequencies produced. In the new comb described in Science, the laser pulses are even shorter and repeated 10 to 100 times faster than in typical frequency combs. The laser emits 10 billion pulses per second, with each pulse lasting about 40 femtoseconds, or quadrillionths of a second, producing extra-wide spacing between individual comb teeth.

Another unusual feature of the new comb is efficient coupling of the laser pulses into a "nonlinear" optical fiber, which dramatically expands the spectrum of frequencies in the comb. Since details of the unusually powerful dime-sized laser were first published in 2008, scientists have doubled the average pulse power directed into the fiber, enabling the comb to reach blue colors for the first time, producing a spectrum across a range of wavelengths from 470 to 1130 nanometers, from blue to infrared. The 50,000 individual colors become visible when the light emitted from the fiber is filtered through a grating spectrometer, a common laboratory instrument that acts like a souped-up prism.

The broad spectrum spanned by the comb—unusual for such a fast pulse rate—enables all the frequencies to be stabilized, using a NIST-developed technique that directly links optical and radio frequencies. Stabilization is crucial for applications.

The ability to directly observe and use individual comb teeth will open up important applications in astronomy, studies of interactions between light and matter, and precision control of high-speed optical and microwave signals for communications, according to the paper. NIST scientists previously have shown, for example, that this type of frequency comb could boost the sensitivity of astronomical tools searching for other Earthlike planets as much as a hundredfold. In addition, the new comb could be useful in a NIST project to develop optical signal-processing techniques, which could dramatically expand the capabilities of communications, surveillance, optical pattern recognition, remote sensing and high-speed computing technologies.

The laser was built by Albrecht Bartels at the Center for Applied Photonics of the University of Konstanz. The frequency comb was built and demonstrated in the lab of NIST physicist Scott Diddams in Boulder, Colo.

As a non-regulatory agency of the U.S. Department of Commerce, NIST promotes U.S. innovation and industrial competitiveness by advancing measurement science, standards and technology in ways that enhance economic security and improve our quality of life.

* A. Bartels, D. Heinecke, and S.A. Diddams. 10 GHz Self-referenced Optical Frequency Comb. Science. Oct. 30, 2009.

Laura Ost | EurekAlert!
Further information:
http://www.nist.gov

More articles from Physics and Astronomy:

nachricht When helium behaves like a black hole
22.03.2017 | University of Vermont

nachricht Astronomers hazard a ride in a 'drifting carousel' to understand pulsating stars
22.03.2017 | International Centre for Radio Astronomy Research

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: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Pulverizing electronic waste is green, clean -- and cold

22.03.2017 | Materials Sciences

Astronomers hazard a ride in a 'drifting carousel' to understand pulsating stars

22.03.2017 | Physics and Astronomy

New gel-like coating beefs up the performance of lithium-sulfur batteries

22.03.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>