Design of photonic crystal delay lines based on enhanced coupled-cavity waveguides

We present an accurate systematic analysis of coupled-cavity waveguide (CCW)-based delay lines, in photonic crystal (PhC) structures with both square and hexagonal patterns. The group velocity profile of different CCW devices, obtained by varying the geometries and the coupling factors, is evaluated by using both the plane-wave expansion (PWE) method and tight binding (TB) model. We determine the optimal geometrical parameters to reduce the group velocity, and demonstrate that the delay line performance can be further enhanced by using high-Q cavities.