Backscattering in monomode periodic waveguides

Abstract

The transport properties of photonic periodic (monomode) waveguides in the presence of realistic fabrication errors are analyzed. They are governed by out-of-plane loss and backscattering. We derive a closed-form expression for the mean-free path that characterizes the transition between the ballistic and localization transport regimes in these waveguides. In agreement with earlier works, the mean-free path is found to be dominantly affected by backscattering for small group velocities. The predictions are quantitatively supported by fully vectorial computational results obtained for two-dimensional periodic waveguides. Three-dimensional (3D) structures, such as single-row-defect photonic-crystal waveguides, have also been analyzed and are shown to provide moderate backscattering in comparison to other 3D waveguides. But in all test cases, we find that the mean-free path is critically small, even for moderately small group velocities of c/50 and for up-to-date fabrication nanofacilities. © 2008 The American Physical Society.