Revised guided mode expansion on dispersive photonic media

摘要

A novel plane-wave-based approach for analytical treatment of dispersive relation is developed and applied to analyze the behavior of electromagnetic waves in plasmonic-photonic-crystal slabs. Here Drude model is used for describing frequency dependent permittivity of plasma rods in host dielectric medium. In the present work, dispersion relation below and above the light line is calculated approximately by means of Maxwell-Garnett effective medium and Revised Plane Wave Method (RPWM). The eigen-functions are then used in Revised Guided Mode Expansion (RGME) as the set of orthonormal bases. Following this procedure, the accurate band structure is obtained. In these kind of methods there are two main sources of error: stair-casing error due to discretization and numerical dispersion due to calculation of frequency domain dielectric matrix elements with finite number of bases. Sub-cell averaging and harmonic inversion methods are suggested to overcome these errors. For investigation purpose we apply this approach for calculating photonic dispersion of dispersive and non-dispersive photonic crystal slabs. Resulted band structures are verified by conventional FDTD method as well.