FDTD investigation of photonic crystal fiber in fiber specklegram sensing

Hetero-core fiber structure consists of a sandwiched structure of fibers with different core diameters. Hetero-core fiber structure has found its application in both intensity based and phase change based sensors. In this paper. an analysis of hetero-core fiber structure in photonic crystal fibers (PCF) and waveguides is presented. With the finite-difference time-domain (FDTD) method, the performance of such a structure in a fiber specklegram sensor and the refractive index modulation on PCF section are investigated. It is found that the unique photonic nanostructures can substantially enhance the sensitivity of the specklegram sensor with added dynamic range tunability, which can lead to many practical applications in optical sensors.