Photonic Crystal Fiber With Two Air-Channel Rings: Fabricating and Assessment to Sense Bending Loss

We report on the fabrication and investigation of special index-guiding photonic crystal fibers (PCFs) with a high leakage property, suitable for sensing applications; the fibers were developed and made on our own. The PCFs were designed to have a couple of air channel rings in a silica matrix. In this design, the PCF modes can effectively leak from the core region, which makes it possible to get a strong resonance coupling between the fundamental mode of the PCF core and the ones of outer silica cladding. Hence, single-mode operation of a sensor based on such fibers becomes easily accomplished and robust. Possible instances of using the PCFs of this design for sensing displacement and bending were explored, including a promising aspect of the fiber's angular positioning with respect to the bending plane.