Cooling Laser Refrigerates Liquid for the Very First Time

For the first time ever, researchers have used a laser to actually refrigerate a liquid rather than heating it up. The new findings could be huge for the future of laser technology.

Since the first laser was invented in 1960, they've always given off heat. These beams of light have never been able to cool liquids because of this. Now, though, researchers have used an infrared laser to cool water by about 36 degrees Fahrenheit.

"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 Peter Pauzauskie, one of the researchers, in a news release. "It was really an open question as to whether this could be done because normally water warms when illuminated."

The researchers chose infrared light for their cooling laser with biological implications in mind; visible light can give cells a damaging "sunburn." The scientists then used a material commonly found in commercial lasers, but then essentially ran the laser phenomenon in reverse. They illuminated a single microscopic crystal suspended in water with infrared laser light to excite a unique glow that has slightly more energy than the amount of light absorbed. This glow carried heat away from both the crystal and the water surrounding it.

"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. "Using laser cooling, it may be possible to prepare slow-motion movies of life in action. And the advantage is that you don't have to cool the entire cell, which could kill it or change its behavior."

The findings reveal that lasers could be used for cooling. In fact, one day the technology could be used to enable high-power lasers for manufacturing, telecommunications or defense applications.

The findings are published in the journal Proceedings of the National Academy of Sciences.

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