7-cell hollow-core photonic bandgap fiber with broad spectral bandwidth and low loss

The limited spectral bandwidth achieved in state-of-the-art hollow-core photonic bandgap fibers (HC-PBGF) has hindered its implementation in a wide range of applications. Here we demonstrate that broad spectral bandwidth and low loss can be simultaneously achieved in 7-cell HC-PBGF. Several 7-cell HC-PBGFs operating at 1550 nm telecom band and 1 μm laser band are present. One of the fibers exhibits a minimum loss of 6.5 dB/km at 1633 nm and a 3 dB bandwidth of 458 nm, approaching a bandwidth to central wavelength ratio of 26%. This is to our knowledge the broadest bandwidth achieved in triangular lattice HC-PBGF and the lowest transmission loss in 7-cell HC-PBGF.