Second harmonic generation in phase matched aluminum nitride waveguides
  We demonstrate second order optical nonlinearity in aluminum nitride on insulator substrates. Using sputter-deposited aluminum nitride thin films we realize nanophotonic waveguides coupled to micro-ring resonators that simultaneously support cavity resonant modes for both visible and IR light. By using phase matched ring resonators, we achieve efficient second-harmonic generation and are able to generate up to 0.5uW of visible light on the chip with a conversion efficiency of -46dB. From the measured response we obtain a second order non-linear susceptibility (\c{hi}2) of 4.7pm/V. Our platform provides a viable route for realizing wideband linear and nonlinear optical devices on a chip. 
W. H. P. Pernice, C. Xiong, C. Schuck and H. X. Tang
physics.optics