Critical dimensions variability-aware design of optomechanical nano beams

Subwavelength geometrical dimension, which often originates from fabrication-induced dimensional deviations variability, can strongly influence the performance of phononic–photonic crystal optomechanical (OM) nanobeams. Here, we present a suitable variability-aware design framework for OM nanobeams by combining extraction of critical dimension variations from scanning electron microscopy images and finite-element modeling. We extracted the impact of deterministic geometrical deviations on the unit cell of the phononic and photonic crystals to identify the most critical fabrication-sensitive parameters. We extended the study to the full cavity, where SEM-informed digital-twin models are used to quantify the influence of systematic dimensional variations on the optical and mechanical resonance frequencies, the optical quality factor, the effective mode volume, and the total OM coupling rate. The results indicate that biased dimensional deviations of ±10 nm exert a minor effect on the overall device performance, whereas larger deviations have a stronger impact on the photonic, phononic, and OM response.