Waveguide couplers for ferroelectric optical resonators
  We report a study of using the same material to fabricate a whispering gallery mode resonator and a coupler. Coupling to high Q whispering gallery modes of the lithium niobate resonator is demonstrated by means of the titanium-doped waveguide. The waveguide coupling approach opens possibilities for simpler and wider practical usage of whispering gallery mode resonators and their integration into optical devices. 
Ivan S. Grudinin, A. Kozhanov, N. Yu
physics.optics