Scientists have discovered a way to build compact and efficient ultraviolet light sources that could enhance information storage, microscopy, and chemical analysis. Engineers modified an 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. The 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.
