Improved Disorder Resilience in Small-Footprint Photonic Cavities with Periodicity Breaking

The ongoing race to miniaturize photonic integrated circuits demands optical cavities not only exhibiting high quality-factors (Q), but that are also compact and robust. However, in conventional photonic crystal (PhC) designs, achieving high-Q typically requires large structures with extended periodicity, which increases sensitivity to fabrication-induced disorder as it multiplies imperfections, hampering reproducibility. In this work, PhC slab cavities as small as 4 × 4 µm2, achieving relatively high Q comparable to conventional large L3 cavities, despite occupying only a fraction of their footprint, are numerically and experimentally demonstrated. These structures are obtained through an optimization process that introduces an aperiodic, yet highly controlled, pattern of holes surrounding the cavity. Multiple replicas of each design are fabricated, and near-field optical characterization, confirming both the Q enhancement and a marked improvement in spectral reproducibility, is performed. The reduced variability across nominally identical devices highlights the potential of engineered aperiodicity as a robust and scalable design strategy for high Q nanophotonic cavities, suitable for dense on-chip integration, paving the way for robust integration in active photonic platforms.