Electromagnetic wave propagation in chiral waveguides

Abstract

In this thesis, electromagnetic field propagation in some chiral waveguide structures is investigated. The problems considered in the thesis are closed and open waveguides with planar and circular cross-sections filled with lossless, reciprocal chiral medium. In chapter 1 historical review of chiral materials and of the closely related concept of optical activity is given and some examples for the potential areas of applications for chiral materials are presented. In chapter 2, constitutive relations are introduced and some different approaches used for chiral medium are given. Wave equations and relations between field components determining electromagnetic wave propagation in unbounded chiral medium are derived. In chapter 3, modal propagation in closed chirowaveguides with perfect electric walls are studied. Using the paralel plate and circular cylindrical chiral waveguides as examples. Formulas for the propagating modal field distribution and for the characterictic equations are derived. Numerical soutions are ontained for the characteristic equations, and for the propagating modal fields and the differences between chiral and nonchiral cases are outlined. In chapter 4, guided modes on open symmetric chiral slab and circular cylindrical chiral rod are studied. Expressions for modal field distributions and characteristic equation are obtained and their numerical solutions are presented. Both the analytical expressions and also the field variations obtained and their numerical solutions show that beside little differences, the discussions made in previous chapter for closed waveguides hold true also for the open waveguides. Appendix A gives the different representations for the constitutive relations in literature and the connection between these relations together with the relations adapted in this thesis. Appendix B includes a detailed analysis of optical rotation and circular dichroism associated with chiral materials. Appendix C gives some details of the derivation of the formulations presented in chapter 2. Finally appendix D gives the figures illustrating the particular field distributions in closed and open waveguides.