Analysis of Micro Strain Sensors based on Photonic Crystal Fibers

Abstract

Photonic crystal fibers are a kind of fiber optics that present a diversity of new and improved features beyond what conventional optical fibers can offer. Due to their unique geometric structure, photonic crystal fibers present special properties and capabilities that lead to an outstanding potential for sensing applications. Photonic crystal fiber based sensors are characterized by high sensitivity, small size, robustness, flexibility and ability for remote sensing. Other advantages concern with the possibility to be used even in the presence of unfavorable environmental conditions such as noise, strong electromagnetic fields, high voltages, nuclear radiation, for explosive or corrosive media, and at high temperatures. These advantages in addition to their fabrication simplicity present them as a very efficient sensing solution for industrial, medical and environmental applications.

The objective of this dissertation is to analyze the performance of photonic crystal fiber based micro-strain sensors and for this purpose Opti-FDTD software is used which allows design of different configurations of photonic crystal fibers.

Firstly, a simple configuration of HC-PCF is presented for application as a micro-strain sensor to exhibit better sensitivity than the typical FBG-based fiber optic strain sensors. Also, cross-sensitivity to changes in surrounding refractive index is avoided. Secondly, a configuration of TC-PCF filled with a metal wire is proposed in order to improve coupling efficiency of fiber and application of such fiber for miniature micro-strain sensor configuration has been demonstrated. Thirdly, birefringence property of hybrid PCF structure is investigated and performance of Ge-doped HPCF as a micro-strain sensor is analyzed to achieve an enhanced value of sensitivity over other PCF based strain sensor configurations.