All-solid photonic bandgap fiber gratings

In this paper, we review advances and our works in all-solid photonic bandgap fiber gratings. Especially, we report the fabrication and characterizations of long period fiber gratings and fiber Bragg grating arrays realized by forming longitudinal periodic index modulation in an low-loss all-solid PBGFs with high-index Ge-doped rods surrounded by a low index Be-doped ring lattice in the cladding. High order resonances between fundamental core mode and cladding LP(01) supermodes are demonstrated and investigated in long period fiber gratings (LPFGs) inscribed in the all-solid photonic bandgap fiber. The fiber Bragg grating array has unusual transmission characteristics, such as large transmission bandwidth and different transmission spectra when launching light into different Ge-doped rods, which is very different from single fiber Bragg grating. These interesting spectral features are analyzed and interpreted.