Highly Effective In-Plane Channel-Drop Filters in Two-Dimensional Heterostructure Photonic-Crystal Slab

摘要

In-plane channel-drop filters consisting of point and line defects in a two-dimensional photonic-crystal slab are investigated. A clear channel-drop operation was successfully demonstrated by employing an ultrahigh quality factor nanocavity and a suitably designed waveguide bend. Moreover, improvements in the channel-drop efficiency of the device were made using a feature of heterostructure photonic crystals, as proposed previously. It is shown theoretically that drop efficiencies much higher than the maximum of 25% for a conventional configuration are achievable using reflection at the heterostructure interface. Drop operations with efficiencies of almost 100% were experimentally demonstrated by the fabricated devices. Moreover, a four-channel drop operation with a high drop efficiency and a constant quality factor was demonstrated by in-plane channel-drop filters in a two-dimensional photonic-crystal slab, with a simple configuration based on heterostructure photonic crystals.