Two accesses to achieve air-core's selective filling of a photonic bandgap fiber

Two simple and low-cost methods for achieving selective filling of air-core photonic bandgap fibers (PBGFs) are proposed and demonstrated. In the first method, liquid paraffin was filled into a PBGF by capillary force. By a two-step filling-cleaving process, all cladding air-holes are finally blocked but the air-core remains open. In the second method, lateral erosion method by hydrofluoric acid was first used to make the cladding air-holes laterally open. Then, the laterally filled liquid paraffin made all cladding air-holes blocked and left only air-core open. With these two methods, the central hollow-core of the PBGF can be selectively filled, which allows for the fabrication of novel hybrid functional-material-silica PBGF for various applications.