Comparison between different dispersion engineering methods in slow light photonic crystal waveguides

This paper compares the performance of different dispersion engineering methods in slow light photonic crystal waveguides, i.e., geometrical parameter optimization and topology optimization. In both methods, the design robustness is enforced by considering the dilated, intermediate and eroded designs corresponding to the under-, standard- and over-etching processes in the manufacturing process.

For vg* = c/50, the parameter optimized design achieves a normalized group index bandwidth product of 0.33 and the topology optimized design achieves 0.53. The numerical results illustrate that waveguides with optimized hole sizes and positions can be efficient for dispersion engineering but that large improvements are possible if irregular geometries are allowed using topology optimization.