Theoretical Study of Photonic Spin-Orbit Interactions Mediated by Topological Scatterers

Project: Research

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Light carries both spin and orbital angular momentum (OAM). Spin is associated with light’s polarization; OAM is associated with light’s spatial field distribution. Their interplay and mutual conversions, i.e. spin-orbit interactions (SOIs), can give rise to numerous novel phenomena and applications such as photonic spin Hall effect, unidirectional transport of signals, and optical micromanipulation of particles. Due to their intrinsic vector nature, SOIs strongly depend on the structural properties of photonic systems. One fundamentally important property is topology, i.e., geometric properties that are preserved under continuous deformations. Therefore, understanding how topology affects SOIs is crucial to the study of light-matter interactions involving angular momentum.In this proposed project, we will carry out a theoretical study to understand how the topology of metallic scatterers affects photonic SOIs. The topology are characterized by the genus (i.e. number of “holes”), which can give rise to current singularities on the scatterers’ surface under the excitation of incident light. Such singularities could modify photonic SOIs. We will explore the photonic SOIs in two regions. In the farfield region, we will investigate the spin/OAM distribution and the mechanical effects of SOIs, i.e. optical forces/torques induced on the scatterers. In the nearfield region, we will investigate how SOIs change the emission properties of a chiral emitter and the scattering/absorption of a chiral particle.The results of this project could uncover the effects of geometric topology on photonic SOIs and bring about novel mechanisms to manipulate angular momentum in chiral light-matter interactions. It will not only deepen our understanding of spin dynamics and singular phenomena of light, but also nourish the field of photonics with new insights and perspectives. In addition, the proposed project could generate distinct approaches to control the propagation and polarization of light for communications and give rise to practical applications in micromanipulation of particles, light emission of nanoantenna, and sensing of chiral molecules. 


Project number9042889
Grant typeGRF
Effective start/end date1/01/2020/12/23