Dispersion Control in Two-Dimensional Superlattice Photonic Crystal Slab Waveguides by Atomic Layer Deposition

D. P. Gaillot, Georgia Institute of Technology
Elton Graugnard, Boise State University
J. Blair, Georgia Institute of Technology
C. J. Summers, Georgia Institute of Technology

Abstract

The frequency and dispersion of photonic bands in two-dimensional triangular-based superlattice photonic crystal Si slab waveguides were manipulated using atomic layer deposition. The samples were conformally coated with increasing thicknesses of TiO₂ and characterized by polarized angular-dependent reflectance measurements, which revealed shifts in the photonic band frequencies of 16% as well as continuous changes in band dispersion. The ability to tune toward zero group velocity by tuning band repulsion between same-polarization bands is demonstrated. Finite-difference time-domain calculations, combined with a dielectric weighting model, were used to assess the observed band and dispersion tuning.