Planar photonic crystal coupled cavity waveguides

We present absolute transmission measurements of coupled cavity waveguides defined within planar photonic crystals. We investigate a range of cavity types and also vary the spacing between cavities. Modal analysis of the individual cavities reveals the symmetries that determine the coupling between adjacent cavities. Enhanced transmission is demonstrated by modifying the photonic crystal lattice. We highlight the need for correct impedance matching at the waveguide input in order to improve the transmission.