Optical waves in finite layered photonic crystals

International audienceWe investigated the propagation of electromagnetic waves in a finite photonic crystal bounded by a substrate and vacuum, and separated from them by a buffer layer and a cap layer. In this realistic geometry, we show the existence of different kinds of localized and resonant modes whose behaviors are strongly dependent on the nature and thickness of the buffer and cap layers, as well as on the width of the photonic crystal. These modes can be confined inside the photonic crystal or at its boundaries and give rise to different possibilities for the guidance of optical waves. The localized and resonant modes are obtained from an analytic calculation of the local and total densities of states within a Green's function formalism for electromagnetic waves of transverse electric polarization. We also evaluate the reflection and transmission coefficients and compare their behaviors with the densities of states