The analogue of a tsunami for telecommunication

For communication and GPS-navigation satellites, it is of great importance to reduce the payload mass as well as to ensure the signal stability. Last year, researchers from the Moscow State University (MSU) together with their Swiss colleagues performed a study that can induce certain improvements in this direction.

The scientists demonstrated (this paper was published in Nature Photonics) that the primary source of noise in microresonator based optical frequency combs (broad spectra composed of a large number of equidistant narrow emission lines) is related to non-linear harmonic generation mechanisms rather that by fundamental physical limitations and in principle reducible.

On December 22st, a new publication in Nature Photonics is appearing where they extend their results. Michael Gorodetsky, one of the co-authors of this paper, professor of the Physical Faculty of MSU affiliated also in the Russian Quantum Centre in Skolkovo, says that the study contains at least three important results: scientists found a technique to generate stable femtosecond (duration of the order of 10-15 seconds) pulses, optical combs and microwave signals.

Physicists used a microresonator (in this particular case, a millimeter-scale magnesium fluorite disk was used, where whispering-gallery electromagnetic oscillations may be excited, propagating along the circumference of the the resonator) to convert continuous laser emission into periodic pulses of extremely short duration. The best known analogous devices are mode-locked lasers that generating femtosecond, high-intensity pulses. Applications of these lasers range from analysis of chemical reactions at ultra-short timescales to eye-surgery.

“In mode-locked femtosecond lasers complex optical devices, media and special mirrors are normally used. However we succeeded in obtaining stable pulses just in passive optical resonator using its own non-linearity,” — Gorodetsky says. This allows, in future, to decrease drastically the size of the device.

The short pulses generated in the microresonator are in fact what is known as optical solitons (soliton is a stable, shape-conserving localized wave packet propagating in a non-linear medium like a quasiparticle; an example of a soliton existing in nature is a tsunami wave). “One can generate a single stable soliton circulating inside a microresonator. In the output optical fiber, one can obtain a periodic series of pulses with a period corresponding to a round trip time of the soliton.” — Gorodetsky explains.

Such pulses last for 100-200 femtoseconds, but the authors are sure that much shorter solitons are achievable. They suggest that their discovery allows to construct a new generation of compact, stable and cheap optical pulse generators working in the regimes unachievable with other techniques. In the spectral domain, these pulses correspond to the so-called optical frequency “combs” that revolutionized metrology and spectroscopy and brought to those who developed the method a Nobel Prize in physics in 2005 ( American John Hall and German Theodor Haensch received the Prize “for their contributions to the development of laser-based precision spectroscopy, including the optical frequency comb technique”). Currently existing comb generators are much larger and more massive.

At the same time, as the scientists show, a signal generated by such a comb on a photodetectors a high-frequency microwave signal with very low phase noise level. Ultra-low-noise microwave generators are extremely important in modern technology; they are used in metrology, radiolocation, telecommunication hardware, including satellite communications. Authors note that their results are critical for such applications as broadband spectroscopy, telecommunications, and astronomy.

Media Contact

Ilya Usov EurekAlert!

More Information:

http://www.msu.ru

All latest news from the category: Physics and Astronomy

This area deals with the fundamental laws and building blocks of nature and how they interact, the properties and the behavior of matter, and research into space and time and their structures.

innovations-report provides in-depth reports and articles on subjects such as astrophysics, laser technologies, nuclear, quantum, particle and solid-state physics, nanotechnologies, planetary research and findings (Mars, Venus) and developments related to the Hubble Telescope.

Back to home

Comments (0)

Write a comment

Newest articles

Lighting up the future

New multidisciplinary research from the University of St Andrews could lead to more efficient televisions, computer screens and lighting. Researchers at the Organic Semiconductor Centre in the School of Physics and…

Researchers crack sugarcane’s complex genetic code

Sweet success: Scientists created a highly accurate reference genome for one of the most important modern crops and found a rare example of how genes confer disease resistance in plants….

Evolution of the most powerful ocean current on Earth

The Antarctic Circumpolar Current plays an important part in global overturning circulation, the exchange of heat and CO2 between the ocean and atmosphere, and the stability of Antarctica’s ice sheets….

Partners & Sponsors