Numerical study of tapered fiber optics as evanescent field sensors

This paper presents some results obtained for the numerical simulation of tapered fiber optics. Some features, insertion loss and effective index, are compared for two main settings of these devices. Two well-established numerical techniques were used here: the Finite Difference - Beam Propagation Method to simulate insertion losses for different tapered fiber diameters and external materials, and the Finite Element Method to simulate the effective index variation at the tapered region of the fiber. The results shows that tapers with concomitant reduction of core and cladding have greater susceptibility than tapers with reduction only in the cladding to changes in surrounding medium, thus being more suitable as sensor device.