Integrated high quality factor lithium niobate microdisk resonators
  Lithium Niobate (LN) is an important nonlinear optical material. Here we demonstrate LN microdisk resonators that feature optical quality factor ~ 100,000, realized using robust and scalable fabrication techniques, that operate over a wide wavelength range spanning visible and near infrared. Using our resonators, and leveraging LN's large second order optical nonlinearity, we demonstrate on-chip second harmonic generation with a conversion efficiency of 0.109 W-1. 
Cheng Wang, Michael J. Burek, Zin Lin, Haig A. Atikian, Vivek   Venkataraman, I-Chun Huang, Peter Stark and Marko Lon\v{c}ar
physics.optics