Subnanometer two-dimensional localization with leakage surface plasmon polaritons arisen from elliptically-polarized...

High-accuracy in-plane localization is increasingly demanded in semiconductor precision manufacturing. However, achieving integrated optical localization with sub-nanometer precision remains a significant challenge. Here, we present an in-plane localization approach by monitoring leakage surface plasmon polariton (SPP) waves generated from an embedded gold cylindrical nanoantenna illuminated by a tightly focused, radially polarized laser beam. The SPP pattern is symmetric when the incident beam is perfectly aligned with the antenna center, but becomes asymmetric upon misalignment. The centroid position of the asymmetric SPP pattern indicates the misalignment between the antenna and the beam, enabling antenna positioning with a precision of 0.8 nm. Characterized by compact integration and a high signal-to-noise ratio, this technique holds promise for high-precision localization and alignment of workpieces in semiconductor manufacturing.