Ultraviolet-inscribed long period gratings in all-solid photonic bandgap fibers.

Long period fiber gratings are fabricated in the cladding rods of all-solid photonic bandgap fibers (PBGFs) by point-by-point side UV illumination. Resonant couplings from fundamental mode to guided and radiative supermodes (rod modes), and bandgap-like modes are identified. We obtained a detailed insight over the modal and dispersive properties of the PBGF through a series of theoretical and experimental investigations on the spectral characteristics and the responses to temperature and high-index liquid of the LPGs.