Realization of single-moded broadband air-guiding photonic bandgap fibers

In this letter, we propose a novel type of air-guiding photonic bandgap fiber, which exhibits an effectively single-mode operation with a low confinement loss over a wide wavelength range, extended from 1460 to 1840 nm. For several realistic structural parameters, the wavelength dependence of the dispersion as well as the confinement loss properties are investigated through a full-vector modal solver based on the finite-element method. In particular, we optimize the structure so as to exhibit the following performance: effectively single-mode operation from 1460 to 1840 nm, with corresponding confinement loss of the fundamental air-guided mode of 8.8times10^-5 dB/km, and enhancement of the confinement loss of the higher order mode of 43 dB/m for ten-ring structure