Unique loss characteristics in TE modes of conventional photonic bandgap fibers.

We report modeling that demonstrates the reduction of transmission loss and broadening of the bandwidth of a conventional hollow-core photonic bandgap fiber (PBF). Numerical investigation reveals that transmission loss of the high-order TE mode is lower than that of the fundamental HE mode in fibers with thick cladding walls. By comparing dispersion curves of PBFs with different core-wall thicknesses, we show that the TE mode has weaker coupling strength to a surface mode than the HE mode. This result opens the way for a wider transmission band and lower transmission loss in PBFs that are subject to the detrimental effects of surface modes.