Transmission spectrum method to measure the photonic bandgap of hollow-core photonic crystal fiber

A full-vector plane-wave method is introduced, particularly in calculating the photonic crystal in-plane photonic bandgap of a 2D triangular structure. Using numerical simulation, we can obtain the in-plane bandgap structure of a hollow-core photonic crystal fiber. In the experiments, we measured the transmission spectra of a hollow-core photonic crystal fiber and a silica rod. And using the numerical calculation we can get the relative transmission spectrum of a hollow-core photonic crystal fiber. Compared with the result of theoretical simulation, we found that they are in accordance with each other, i.e. they have the same bandgap in about the same normalized frequency.