Suspended-core holey fiber for evanescent-field sensing

Abstract

A simple fabrication technique for a silica suspended-core holey fiber design is presented that features a higher air-filling fraction than most holey fibers, making it ideal for evanescent-field-sensing applications. The holes in the fiber are defined through mechanical drilling of the preform, which is a significantly quicker and more straightforward approach to the customary stacking method. During the draw, the shape of the holes are manipulated so that the final fiber design approximates that of an air-suspended rod with three fine struts supporting the core. Modeling reveals that the modal overlap is greater than 29% at 1550 nm for a core diameter of 0.8 μm, which is significantly higher than any previously reported index-guiding structure used for sensing. A basic gas sensor is demonstrated using acetylene as the sensing medium and the results are reported. © 2007 Society of Photo-Optical Instrumentation Engineers.