Propagation loss measurements and Fabry–Pérot mode analysis using out-of-plane light scattering in photonic crystal waveguides

An experimental technique is presented for the measurements of propagation losses in planar photonic crystal waveguides (PhC-WGs). When the guided light interacts with the air holes, it is partially scattered out of the propagation plane. The intensity of this diffracted light is measured along the PhC-WG and the propagation losses are deduced from its attenuation. To illustrate this, the Fabry–Pérot-type mode of a single-line defect PhC-WG is investigated. The propagation loss values obtained experimentally agree well with theoretical predictions. Finally, a study of single-line defect 60° bends shows that this technique also provides an efficient method to obtain modal information along PhC structures.