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Abstract. Some important properties of photonic wire Bragg grating structures have been investigated. The design, obtained as a generalisation of the full-width gap grating, has been modelled using 3D finite-difference time-domain simulations. Different types of stop-band have been observed. The impact of the grating geometry on the lowest order (longest wavelength) stop-band has been investigated -and has identified deeply indented configurations where reduction of the stop-bandwidth and of the reflectivity occurred. Our computational results have been substantially validated by an experimental demonstration of the fundamental stop-band of photonic wire Bragg gratings fabricated on silicon-on-insulator material. The accuracy of two distinct 2D computational models based on the effective index method has also been studied -because of their inherently much greater rapidity and consequent utility for approximate initial designs. A 2D plan-view model has been found to reproduce a large part of the essential features of the spectral response of full 3D models.

Photonic crystal tapers have been designed for coupling of light from ridge waveguides into low group velocity photonic crystal channel guides. The coupling efficiency is increased from 3 % (case of butt-coupling) to 97 % for frequencies in the band-edge region, corresponding to a group index close to 100, as predicted using 2D finite-difference time-domain simulations.

Abstract-We present the design, fabrication, and characterization of a microcavity that exhibits simultaneously high transmission and large resonance quality-factor (Q-factor). This microcavity is formed by a single-row photonic crystal (PhC) embedded in a 500-nm-wide photonic wire waveguide-and is based on silicon-on-insulator. A normalized transmission of 85%, together with a Q-factor of 18 500, have been achieved experimentally through the use of carefully designed tapering on both sides of each of the hole-type PhC mirrors that form the microcavity. We have also demonstrated reasonably accurate control of the cavity resonance frequency. Simulation of the device using a three-dimensional finite-difference time-domain approach shows good agreement with the experimental results.Index Terms-Microcavities, photonic crystal (PhC), photonic wires (PhWs), quality-factor ( -factor), silicon-on-insulator (SOI).

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