Critical optical coupling between a GaAs disk and a nanowaveguide   suspended on the chip
  We report on an integrated GaAs disk/waveguide system. A millimeter-long waveguide is suspended and tapered on the chip over a length of 25 {\mu}m to evanescently couple to high Q optical whispering gallery modes of a GaAs disk. The critical coupling regime is obtained both by varying the disk/guide gap distance and the width of the suspended nanoscale taper. The experimental results are in good agreement with predictions from the coupled mode theory. 
C. Baker, C. Belacel, A. Andronico, P. Senellart, A. Lemaitre, E.   Galopin, S. Ducci, G. Leo and I. Favero
physics.optics