Experimental

Lasers are often misunderstood, according to chemical physicist and JQI Fellow Yu Liu. “People usually think of lasers as heating things up, but if you use the right frequency of lasers and target the right type of atoms, you can actually take energy away,” Liu says. This technique—laser cooling—is his specialty.

It’s not easy making green. For years, scientists have fabricated small, high-quality lasers that generate red and blue light, but the same method hasn’t worked as well in building tiny lasers that emit green light. Green laser pointers have existed for 25 years but only produce light in a narrow spectrum of green and are not integrated in chips. Researchers refer to the dearth of stable, miniature lasers in this region of the visible-light spectrum as the “green gap.” Now a team led by JQI Fellow Kartik Srinivasan has closed the green gap by modifying a tiny optical component: a ring-shaped microresonator, small enough to fit on a chip.