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!
Data use draining your battery? Tiny device to speed up memory while also saving power
14.12.2018 | Purdue University
Studying how unconventional metals behave, with an eye on high-temperature superconductors
13.12.2018 | Princeton University
The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.
Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...
What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...
A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.
The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...
A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.
Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...
Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...
12.12.2018 | Event News
10.12.2018 | Event News
06.12.2018 | Event News
14.12.2018 | Power and Electrical Engineering
14.12.2018 | Physics and Astronomy
14.12.2018 | Physics and Astronomy