Self-frequency doubling in a laser-active whispering-gallery resonator

Lasing and self-frequency doubling are achieved in a millimeter-sized laser-active whispering-gallery resonator made of neodymium-doped lithium niobate. A low-cost 808-nm laser diode without external frequency stabilization is sufficient to pump the neodymium ions. Laser oscillation around 1.08 mu m drives a frequency-doubling process within the same cavity providing green light. The electrical-optical efficiency of the system reaches up to 2 x 10(-4). To the best of our knowledge, this is the first demonstration of combining lasing and. chi((2)) frequency conversion in a single high-Q whispering-gallery resonator. This approach is general and can be applied to other materials and other nonlinear optical processes. (C) 2017 Optical Society of America.