Self-focused beams to couple light into a whispering-gallery mode   resonator
  We propose an original method to couple light into a whispering-gallery mode resonator. This method benefits from the mode selectivity and robustness of the prism-coupling along with the single-mode propagation of the fiber taper. It consists in a prism shaped crystal with a waveguide inscribed inside it. The waveguide is self-inscribed in-situ by beam self-trapping to allow an optimum coupling to a given resonator. 
Kien Phan Huy, Jassem Safioui, Jean-Yves Rauch, Patrice F\'eron, and   Mathieu Chauvet
physics.optics