Ultralow mode-volume photonic crystal nanobeam cavities for high   efficiency coupling to individual carbon nanotube emitters
  We report on high efficency coupling of individual air-suspended carbon nanotubes to silicon photonic crystal nanobeam cavities. Photoluminescence images of dielectric- and air-mode cavities reflect their distinctly different mode profiles and show that fields in the air are important for coupling. We find that the air-mode cavities couple more efficiently, and estimated spontaneous emission coupling factors reach a value as high as 0.85. Our results demonstrate advantages of ultralow mode-volumes in air-mode cavities for coupling to low-dimensional nanoscale emitters. 
R. Miura, S. Imamura, R. Ohta, A. Ishii, X. Liu, T. Shimada, S.   Iwamoto, Y. Arakawa, Y. K. Kato
cond-mat.mes-hall