Nanofiber Fabry-Perot microresonator for non-linear optics and cavity   quantum electrodynamics
  We experimentally realize a Fabry-Perot-type optical microresonator near the cesium D2 line wavelength based on a tapered optical fiber, equipped with two fiber Bragg gratings which enclose a sub-wavelength diameter waist. Owing to the very low taper losses, the finesse of the resonator reaches F = 86 while the on-resonance transmission is T = 11 %. The characteristics of our resonator fulfill the requirements of non-linear optics and cavity quantum electrodynamics in the strong coupling regime. In combination with its demonstrated ease of use and its advantageous mode geometry, it thus opens a realm of applications. 
C. Wuttke, M. Becker, S. Br\"uckner, M. Rothhardt and A.   Rauschenbeutel
quant-ph physics.optics