A novel low-loss splice for photonic bandgap fiber gas sensor

This paper presents a novel low-loss splice between the Photonic bandgap fiber (PBGF) and conventional step index fiber, for making PBGFs more functional. The solidcore fiber is butt-coupled to a PBGF using a mechanical splice surrounded by the block. The gap between the butt-coupled fibers is the most important parameter for keeping good output coupling efficiency and allowing for gas diffusion. For achieving the small gap, a focused ion beam (FIB) milling technique was developed for getting clean fiber surface. The achieved gap is adjustable from 0 to 400μm. And a typical value at the gap of 20μm was 1.6 dB.