A paper on the research is newly published in Optics Express. The research was led by Mona Jarrahi and Tal Carmon, assistant professors in the Department of Electrical Engineering and Computer Science. The experiment was performed by Jeremy Moore and Matthew Tomes, both graduate students in the same department.
The researchers have optimized a type of optical resonator to take an infrared signal from relatively cheap telecommunication-compatible lasers and, using a low-power, nonlinear process, boost it to a higher-energy ultraviolet beam.
Their optical resonator is a millimeter-scale disk with a precisely engineered shape and smooth surface polishing to encourage the input beam to gain power as it circulates inside the resonator.
"We optimized the structure to achieve high gain over a broad range of optical wavelengths," Jarrahi said. "This allows us to make low-cost, wavelength-tunable ultraviolet sources using low-infrared power levels."
The researchers used their resonator to generate the fourth harmonic of the infrared beam they started with.
Like the harmonic distortions you get from new sound frequencies when you crank up a loudspeaker, engineers can generate harmonics of light by using the right materials. By pushing light beams through a nonlinear medium, they can coax out offshoot beams that are double, or in this case, quadruple the frequency and energy of the input beam, and one-quarter of the original wavelength.
Lasers get progressively more difficult to generate and more inefficient, as engineers aim for shorter wavelengths, the researchers said.
"As we go from green to blue, the efficiency of the laser goes down. Going to UV lasers is even harder," Jarrahi said. "This principle was first suggested by Einstein and is the reason why green laser pointers do not actually contain a green laser. It is actually a red laser and its wavelength is divided by two to become green light."
Ultraviolet light sources have applications in chemical detection, crisper medical imaging and finer lithography for more sophisticated integrated circuits and greater computer memory capacity.
The paper is titled "Continuous-wave ultraviolet emission through fourth-harmonic generation in a whispering-gallery resonator." The research was funded by the National Science Foundation and the Air Force Office of Scientific Research.
The University of Michigan College of Engineering is ranked among the top engineering schools in the country. At more than $130 million annually, its engineering research budget is one of largest of any public university. Michigan Engineering is home to 11 academic departments and a National Science Foundation Engineering Research Center. The college plays a leading role in the Michigan Memorial Phoenix Energy Institute and hosts the world class Lurie Nanofabrication Facility. Michigan Engineering's premier scholarship, international scale and multidisciplinary scope combine to create The Michigan Difference. Find out more at http://www.engin.umich.edu/.
Nicole Casal Moore | EurekAlert!
Researchers take next step toward fusion energy
16.11.2017 | Texas A&M University
Desert solar to fuel centuries of air travel
16.11.2017 | SolarPACES
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
21.11.2017 | Physics and Astronomy
21.11.2017 | Materials Sciences
21.11.2017 | Health and Medicine