Optical frequency combs are a key technology for optical precision measurements. So far, most frequency combs operate in the near-infrared regime (NIR). Many applications, however, require combs in the ultraviolet (UV), visible (VIS) or mid-infrared (MIR) spectral ranges. This can be achieved by making use of nonlinear-optical processes. In this contribution, we demonstrate the e ffi cient conversion of frequency combs with a repetition rate of 21 GHz to UV, VIS and MIR wavelengths in a synchronously driven high-Q microresonator with second-order optical nonlinearity. This opens up a new path for applications including, but not limited to, molecular sensing and quantum optics.
in Laser Resonators, Microresonators, and Beam Control Xxi. vol. 10904 (Issue), A. V. Kudryashov, A. H. Paxton, and V. S. Ilchenko, Eds., ed Bellingham: Spie-Int Soc Optical Engineering, 2019.