Finite difference beam propagation method for analyzing bend enhanced optical touch sensor

Abstract

Analysis of waveguides by computational methods is very important and widely used in optical fiber communications since the power loss due to bending of the optical fibers decreases the channel capacity of the optical fiber links. These systems require proper analysis tools to understand the effects of corruption and degradation of the channel capacity resulting from external disturbances. Although telecommunication systems tries to analyze the corruption in the opti- cal waveguides such as power attenuation and channel degregation, optical waveguide based sensor applications trie to seek ways of using these changes or corruptions for sensing different properties of the environment. Since optical sensors carry some ad- vantages as being insensitive to electromagnetic interferance , having long durability and high precision; they deserve certain attention. The aim of this thesis is to provide an analysis method for electrical field and power propagation in waveguides undergoing severe bending by using finite difference beam propagation methods in three dimensions, where the waveguides are bent severely so that the considerable amount of power radiation occurs to the outside of the waveguide with the intention of sensing. As an application in this thesis we propose and analyze a bend enhanced optical touch sensor with the developed three dimensional finite difference beam propagation methods and validate our analysis and reason on the operability of this sensor.