7-cell core hollow-core photonic crystal fibers with low loss in the spectral region around 2 μm

Several 7 cell core hollow-core photonic crystal fibers with bandgaps in the spectral range of 1.4 microm to 2.3 microm have been fabricated. The transmission loss follows the approximately lambda(-3) dependency previously reported, with a minimum measured loss of 9.5 dB/km at 1.99 microm. One fiber with a transmission loss of 26 dB/km at 2.3 microm is reported, which is significantly lower than the transmission loss of solid silica fibers at this wavelength.