Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Transportable laser

23.01.2018

The Physikalisch-Technische Bundesanstalt (PTB) has developed a frequency-doubling unit for transportable lasers

The Physikalisch-Technische Bundesanstalt (PTB) is known for providing time e.g. for radio-controlled clocks. For this purpose, it operates some of the best cesium atomic clocks in the world. At the same time, PTB is already developing various atomic clocks of the next generation.


These are the laser setups of the optical atomic clock being developed at the QUEST Institute of PTB.

Credit: PTB

These clocks are no longer based on a microwave transition in cesium, but they rather operate with other atoms that are excited using optical frequencies. Some of these new clocks can even be transported to other locations. At its QUEST Institute, PTB is currently developing a transportable optical aluminum clock in order to measure physical phenomena (such as the red shift that was predicted by Einstein) outside a laboratory.

A prerequisite for this is that the required lasers are able to endure transportation to other locations. PTB physicists have therefore developed a frequency-doubling unit that will even continue to operate when it has been shaken at three times the Earth's gravitational acceleration. The results have been published in the current issue of the Review of Scientific Instruments.

It was Einstein who found out that two clocks that are located at two different positions in the gravitational field of the Earth tick at different speeds. What initially sounds like a bizarre idea has quite practical effects: Two optical atomic clocks having an extremely small relative measurement uncertainty of 10-18 can measure the difference in height between arbitrary points on the Earth at an accuracy of just one centimeter.

This so-called "chronometric levelling" represents an important application of clocks in geodesy. One of the prerequisites for this is that the optical frequencies of the two clocks can be compared e.g. via glass fibers.

PTB is currently developing several different types of atomic clocks that can each be transported in a trailer or in a container. Their operation outside a protected laboratory, however, involves many challenges: The ambient temperature, for example, is much less stable. Furthermore, significant shocks may occur during transportation. This is why optical structures that have worked perfectly well in the laboratory may initially be unusable at the destination. They must painstakingly be readjusted - which leads to a loss of valuable research time.

This last-mentioned problem concerns in particular the transportable aluminum clock that is being developed at the QUEST Institute. This clock requires, among other things, two UV lasers at 267 nm. For this wavelength, it is not possible to simply buy a laser diode. Instead, a long-wave infrared laser must be frequency-doubled twice in succession. During this process, the light is coupled into a closed ring of four mirrors so that a high optical power is circulating within the ring.

A non-linear crystal placed in this ring transforms the circulating light into light of half the wavelength. Due to the dichroic coating of the mirror, it passes out of the resonator and is then used for reading the clock. The QUEST Institute has developed a design for this so-called frequency-doubling cavity which is based on a monolithic - and therefore highly stable - frame onto which all mirrors and the crystal are mounted. The set-up is sealed to be gas-tight to the outside in order to protect the crystal, which is highly sensitive even to the slightest contaminations.

The developers of the cavity were able to demonstrate on a prototype that it also doubles the laser light while it is exposed to accelerations of 1 g. Furthermoe, it was shown that the frequency doubling efficiency is not impaired after being subjected to accelerations of up to 3 g for 30 minutes. This corresponds to five times the value stated in Standard ISO 13355:2016 about road transportation on trucks. The cavity is, however, not only mechanically robust, but it is just as efficient as comparable systems that have been developed by research groups of other institutes. Moreover, 130 hours of uninterrupted continuous operation was demonstrated.

In view of these properties, the QUEST Institute has made several of these doubling cavities for different wavelengths (not only for UV) which became integral components of various quantum-optical experiments, with the aim of providing these experiments reliably with laser light. Moreover, a German optomechanics company has licensed the design in order to use it as a basis for a commercial product. This project was supported by the Deutsche Forschungsgesellschaft (grant CRC 1128 geo-Q, Project A03, CRC 1227 DQ-mat, Projects B03 and B05) and the Leibniz-Gemeinschaft (SAW-2013-FBH-3).

###

Contact

Prof. Dr. Piet O. Schmidt, QUEST, phone: +49 (0)531 592-4700, e-mail: piet.schmidt@ptb.de

Scientific publication

S. Hannig, J. Mielke, J. Fenske, M. Misera, N. Beef, C. Ospelkaus, P.O. Schmidt: A highly stable monolithic enhancement cavity for second harmonic generation in the ultraviolet. Review of Scientific Instruments 89, 013106 (2018)

A "Scilight" of the publication was published by AIP ("A robust frequency doubling cavity makes a transportable laser source for use in a UV optical clock"): http://scitation.aip.org/content/aip/journal/sci/2018/3/10.1063/1.5021479

Media Contact

Piet O. Schmidt
piet.schmidt@ptb.de
49-053-159-24700

http://www.ptb.de/ 

Piet O. Schmidt | EurekAlert!

Further reports about: PTB QUEST Transportable Ttansportable laser gravitational laser light wavelength

More articles from Physics and Astronomy:

nachricht Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics

nachricht What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin

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: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>