Ultra-large bandwidth hollow-core guiding in all-silica Bragg fibers   with nano-supports
  We demonstrate a new class of hollow-core Bragg fibers that are composed of concentric cylindrical silica rings separated by nanoscale support bridges. We theoretically predict and experimentally observe hollow-core confinement over an octave frequency range. The bandwidth of bandgap guiding in this new class of Bragg fibers exceeds that of other hollow-core fibers reported in the literature. With only three rings of silica cladding layers, these Bragg fibers achieve propagation loss of the order of 1 dB/m. 
G. Vienne, Y. Xu, C. Jakobsen, H.-J. Deyerl, J.B. Jensen, T. Sorensen,   T.P. Hansen, Y. Huang, M. Terrel, R.K. Lee, N.A. Mo...