Computation of Radiation Leakage in Photonic Crystal Waveguides

We have performed accurate analysis of radiation leakage in the propagation plane of photonic crystal (PhC) waveguides using a modification of the classical supercell approach. We have opened the classical supercell in the direction perpendicular to the propagation direction in order to take the radiation losses into account. Using this so-called “open supercell”, the waveguide eigenvalue analysis becomes complex valued as well as the constant for the periodic boundary condition. Quite surprising results have been achieved when analyzing the radiation loss along PhC waveguide channels for various numbers of confining crystal layers. We can show, that for a certain range of frequencies PhC waveguides surrounded by only one crystal layer may still support efficient waveguiding operation