University of Washington researchers are the first to solve a decades-old puzzle — figuring out how to make a laser refrigerate water and other liquids under real-world conditions and the discovery could help industrial users “point cool” tiny areas with a focused point of light.
Microprocessors, for instance, might someday use a laser beam to cool specific components in computer chips to prevent overheating and enable more efficient information processing, says a study to be published the week of Nov. 16 in the Proceedings of the National Academy of Sciences.
The team used an infrared laser to cool water by about 36 degrees Fahrenheit — a major breakthrough in the field.
“Typically, when you go to the movies and see Star Wars laser blasters, they heat things up. This is the first example of a laser beam that will refrigerate liquids like water under everyday conditions,” said senior author Peter Pauzauskie, UW assistant professor of materials science and engineering.
Scientists could also use a laser beam to precisely cool a portion of a cell as it divides or repairs itself, essentially slowing these rapid processes down and giving researchers the opportunity to see how they work. Or they could cool a single neuron in a network — essentially silencing without damaging it — to see how its neighbors bypass it and rewire themselves.
“There’s a lot of interest in how cells divide and how molecules and enzymes function, and it’s never been possible before to refrigerate them to study their properties,” said Pauzauskie, who is also a scientist at the U.S. Department of Energy’s Pacific Northwest National Laboratory in Richland, Washington.
To achieve the breakthrough, the UW team used a material commonly found in commercial lasers but essentially ran the laser phenomenon in reverse. They illuminated a single microscopic crystal suspended in water with infrared laser light to excite a unique kind of glow that has slightly more energy than that amount of light absorbed.
To determine whether the liquid is cooling, the instrument also projects the particle’s “shadow” in a way that allows the researchers to observe minute changes in its motion.
One day the cooling technology itself might be used to enable higher-power lasers for manufacturing, telecommunications or defense applications, as higher-powered lasers tend to overheat and melt down.
“Few people have thought about how they could use this technology to solve problems because using lasers to refrigerate liquids hasn’t been possible before,” he said. “We are interested in the ideas other scientists or businesses might have for how this might impact their basic research or bottom line.”