Researchers funded by the Swiss National Science Foundation have made a chip-based device that can generate a laser signal with frequencies spaced in a comb-like fashion. Their work could be used in telecommunications applications and in chemical analysis.
In general, light and water waves alike stretch out and dissipate as they move further and further away from their source. However, there is a type of wave that maintains its shape as it propagates: solitons.
Researchers funded by the Swiss National Science Foundation (SNSF) have successfully produced optical solitons – light waves that retain their shape – using a microresonator. The light is composed of a range of frequencies separated very precisely by the same distance, producing what physicists call a frequency comb, since it resembles the regular spacing between the teeth of a comb.
A new record
To generate the solitons, researchers at EPFL and the Russian Quantum Center in Moscow have used microresonators. “These microscopic ring-shaped structures are made from very fine silicon nitride,” explains Tobias Kippenberg, the EPFL group leader.
“They are capable of storing for a few nanoseconds the light of the laser to which they are coupled. This period of time is sufficient for the light to circumnavigate the ring thousands of times and to accumulate there, which strongly increases the intensity of the light.” The interaction between the microresonator and the light becomes non-linear. The laser, which is normally continuous by nature, is converted into ultra-short pulses: solitons.
By adapting the parameters for manufacturing microresonators, the EPFL researchers additionally managed to generate a so-called soliton Cherenkov radiation. This broadens the frequency spectrum: the comb contains a greater number of teeth. Published in Science (*), the results have set a new record for this type of structure. The frequencies generated now extend over two thirds of an octave compared with the frequency of the laser.
“These results represent a promising advance for applications that require many widely spaced frequencies,” says Kippenberg. In the context of optical communications, one single laser would be enough to create a range of individual frequencies which could separately carry information. Chemical spectroscopy and atomic timekeeping are other potential fields of application. “We have filed a patent, since there is potential for further technological developments,” says Kippenberg.
Frequency combs, a discovery by Theodor Hänsch and John Hall that won them a Nobel Prize for Physics in 2005, are generally created using very large lasers. “The ability to produce optical frequency combs using small chips represents an interesting advance for making them more user-friendly,” says Tobias Kippenberg.
(*) V. Brasch et al.: Photonic chip–based optical frequency comb using soliton Cherenkov radiation, Science 10.1126/science.aad4811 (2015).
(Available to journalists as a PDF file from the SNSF: firstname.lastname@example.org)
Prof. Tobias J. Kippenberg
Laboratory of Photonics and Quantum Measurements
Tel: + 41 21 693 44 28 or +41 79 535 00 16
(Reachable from 7 January, 11.30 a.m.)
This press release can be found on the website of the SNSF:
Media - Abteilung Kommunikation | idw - Informationsdienst Wissenschaft
Hope to discover sure signs of life on Mars? New research says look for the element vanadium
22.09.2017 | University of Kansas
22.09.2017 | Forschungszentrum MATHEON ECMath
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy