Near field modelling and measurement of tapered optical fibre devices

Abstract

A finite difference beam propagation method (FD-BPM), particularly suited for modeling tapered optical fibers, is presented. It is used to predict the behavior of the evanescent field within the region of the taper waist. A propagative algorithm is required to model the tapers since the majority of the taper profiles results in non-adiabatic devices. The main factors for such behaviors are the size of the taper waist and the external refractive index value. Several tapers are experimentally characterized using scanning near field optical microscope to directly measure the evanescent field strength as a function of distance from the taper waist.