Novel dispersion-adapted photonic crystal cavity with improved disorder stability

We present a photonic crystal cavity (PhCC) design methodology that is based on systematically engineering the dispersion curve of a PhC line-defect. Our combined numerical and analytical approach offers the option of using a variety of different defect modifications to create a gentle-confinement cavity with a Gaussian profile. Here, we demonstrate the principle of the method by employing relatively large hole-shifts (tens of nanometers), aiming for improved stability against disorder. Such improved stability compared with the established hetero-structure design approach is then experimentally confirmed on cavities fabricated in silicon. We point out some design features that are linked to this improved disorder stability. In addition, we note that different types of cavities exhibit dissimilar fabrication-limited Q-factors despite identical fabrication process.