Modeling the tapering effects of fabricated photonic crystal fibers and tailoring birefringence, dispersion, and supercontinuum generation properties

Abstract

The effects of tapering fabricated air-silica photonic crystal fibers (PCFs) by tailoring the key modal and nonlinear properties of PCFs have been studied by analyzing the tapered structure using a finite difference mode calculation algorithm. The process of tapering is simulated through repeatedly redefining the geometry of the fiber cross section in a progressively tapered dimension preserving the shape. We tested the performance of the analysis by evaluating the modal characteristics, namely, the mode-effective area, birefringence, dispersion, nonlinearity, and supercontinuum properties of some well-known PCF examples under successive tapered conditions. Tapering, as an additional parameter, is seen to improve birefringence of a typical high-birefringence PCF by 1 order of magnitude. The analysis also estimates the extent of tapering that is required to achieve a target amount of evanescent field that has potential applications in an evanescent field sensor. Our investigation with tapered PCF structures includes tailoring dispersion properties and increasing nonlinearity, which leads to broader and lower threshold supercontinuum generation. The analysis should, therefore, be useful as a ready technique for taper analysis of any arbitrary structure PCF and also in PCF-preform (stacking structure) analysis, which can provide preestimates of properties in a targeted dimension of the final PCF before drawing.