Modulation of Junction Defects Created by Crossing Photonic Crystal Waveguides

In optical circuits, functional elements are often placed on waveguide junctions. We show that a junction in photonic crystals (PCs) possesses localized modes very close to the bandpass of waveguides. Their mode resonances and field patterns can be controlled by modulating the PC waveguides. It is expected that functions such as switching and routing could be developed naturally by using junction modes without any special design of microcavities. Our calculation results can be explained by the coupled mode theory.