Propagation loss computation of W1 photonic crystal waveguides using the cutback technique with the 3D-FDTD method

Abstract

Identifying the origins of the large propagation losses in substrate-type photonic crystal waveguides and subsequently reducing them by means of structural optimization requires a numerical model, which is flexible and accurate enough to allow a quantitative comparison. In this article we discuss the applicability of the cutback-method on numerical transmission spectra obtained from the 3D finite difference time domain (FDTD) method. We present two different implementations of the cutback-method and discuss their suitability to predict the propagation losses of fabricated structures. We compare the computed propagation losses with experimental data and find a remarkable agreement for almost the entire single mode regime of single line-defect waveguides.