Optimized Design of Unsymmetrical Gap Nodeless Hollow Core Fibers for Optofluidic Applications

A tubular lattice nodeless hollow core photonic crystal fiber (NHC-PCF) with unsymmetrical gap design is proposed. The design relies on one large unsymmetrical gap between the fiber cladding tubes and aligned with a slot running down the entire length of the fiber. The special one large gap design of the NHC-PCF will bring great convenience for its optofluidic applications and will also facilitate fiber drawing process or fiber microcutting postprocess without resulting in operation difficulties and extra principle loss, making it a useful hollow core fiber platform for gas sensing and other optofluidic applications. We have investigated the optimized gap parameters, the confinement loss, mode birefringence, mode pattern, and fraction of power in the core of this type of fiber in detail. The fiber parameters have been optimized to achieve low confinement loss, reasonable core size, and large gap simultaneously for engineering realization. The unique advantages and potential optofluidic applications of the unsymmetrical gap NHC-PCF with an exposed core are also discussed.