Enhanced transmission in photonic crystals microcavity filters in ridge-waveguide format

Abstract

The design and applications of one- or two-dimensional photonic crystal microcavity filters have been widely investigated and reported over the last several years. The functionality of these devices can be tailored to suit any specific application such as optical filters, sensors and optical memory. However, the coupling of light into these miniature devices has always been a challenge, in particular, when light transits the waveguide region to the photonic crystal structures. This modal transition results in scattering losses leading to low optical transmission. In this work, twodimensional photonic crystal microcavity filter structures with mode-matching features embedded in ridge waveguides have been designed using Finite Domain Time Difference modeling tool and fabricated on GaAs/AlGaAs substrate using Electron Beam Lithography and Reactive Ion Etching. An increase in optical transmission of about 80 % is obtained by the addition of the mode-matching features.