Analysis of Q-factors of structural imperfections in triangular cross-section nanobeam photonic crystal cavities

We present comprehensive and quantitative analysis of the effect of structural imperfections on quality (Q)-factors in triangular cross-section nanobeam photonic crystal cavities. We investigated statistically the optical losses due to the various imperfections in the air holes' positions, radii, alignments, and surface roughness, among other factors. It is revealed that the Q-factor decreases significantly from an ideally designed value due to such imperfections, with the main influence being the asymmetric alignment of the air hole line relative to the center of the nanobeam in the currently used fabrication process. Our analysis provides important information for achieving higher Q-factors in the cavities.