Resonant Metaphotonics: From Optical Manipulation to Chiral Metasurfaces

Abstract

This thesis develops a resonance-centric framework for metaphotonics and optomechanics, focusing on how resonant modes govern light–matter interactions at the subwavelength scale. The unifying theme is that resonances provide a minimal and physically transparent language to describe, predict, and engineer enhanced forces, torques, nonlinear responses, and chiral effects in both isolated particles and structured metasurfaces. Chapters 1 and 2 establishes a theory-first foundation based on Maxwell equations, multipole ex pansion, eigenmode analysis, resonant state expansion, and temporal coupled-mode theory. Emphasis is placed on identifying simple models that capture the essential physics of resonant excitation, decay, and interference, while remaining general across optics and linear acoustics. This framework clarifies the role of quality factors, radiative and non-radiative losses, and mode symmetry in shaping observable responses. Chapter 3 applies this formalism to radiation forces and torques on resonant particles. It is shown that Mie resonances in high-index dielectric particles lead to strong, spectrally selective enhancement of optical and acoustic forces, recoil effects, and angular momentum transfer. New regimes of motion are identified, including resonant hopping, orbiting, super-torque regime, lateral recoil forces, stable lift, and angular sorting of particles. The analysis includes electric, magnetic, and higher-order multipolar contributions and reveals how resonance-induced sign changes and interference effects enable force and torque control beyond the Rayleigh limit. Chapter 4 addresses resonant metasurfaces, with a focus on chirality and polarization control. A general strategy for chiral encoding is developed, based on the interplay between lattice symmetry and resonator geometry. It is demonstrated that strong linear and nonlinear circular dichroism can emerge from mode coupling and symmetry breaking, even in structures composed of achiral meta-atoms. Res onances are shown to act as symmetry-selective amplifiers, enabling gradient chirality, maximal optical chirality, and efficient nonlinear chiral light generation. Finally, Chapter 5 summarises the key findings, concludes the thesis, and outlines future research directions. Overall, the thesis provides a unified resonant perspective on radiation forces and torques and meta surface design. The results establish general design principles for exploiting resonances to enhance and control mechanical, polarization, and nonlinear phenomena, with direct relevance to optical trapping, particle sorting, chiral photonics, and resonant nanophotonic devices