Fabrication of all-solid photonic bandgap fiber coupler

We report the fabrication of a tunable all-solid photonic bandgap fiber coupler based on the side-polishing technique. This device is believed to be the first demonstration of a photonic bandgap fiber coupler to eliminate the contamination of the open air holes. By adjusting the length of the interaction section, the tunable coupling ratio as much as 92.5% at 1550 nm is achieved. The investigation of the spectrum properties shows that the coupler has excellent tunability properties, for which the coupling ratio can be smoothly and continuously controlled.