טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentYuri Gorodetski
SubjectGeometric Spin-Orbit Interaction of Surface Waves
DepartmentDepartment of Mechanical Engineering
Supervisor Full Professor Hasman Erez


Abstract

Optical spin-orbit interaction (SOI) occurs when the intrinsic angular momentum - spin (polarization helicity) and the extrinsic (orbital/linear) momentum of the electromagnetic field are coupled. In general, SOI lies in the origin of various remarkable effects in diverse fields of physics and at different scales, ranging from stellar objects to fundamental particles. In these effects, the SOI implies a correction of the generalized momentum, thereby imposing a dispersion relation modification. This modification is manifested by a spin-dependent geometric phase which may lead to a symmetry breaking even in structures with full rotational symmetry. Here we exploit plasmoinic nanoscale structures to obtain SOI. In particular, we achieve a coupling of the intrinsic angular momentum (AM) of the photons to a linear or an orbital angular momentum of the surface waves. This allows us to manipulate the surface plasmonic waves in a spin-dependent manner and paves the way to a new branch of nanophotonics - the spinoptics.

We demonstrate an excitation of plasmonic vortices with spin-dependent vorticity in microcavities. The remarkable phenomenon of a spin-dependent shift of the focal spot in a focusing plasmonic device is also measured. We achieved a spin-controlled enhanced transmission through a coaxial nanoaperture which exhibited a crucial role of an AM selection rule in a light-surface plasmon scattering process. We demonstrated a plasmonic equivalent of the Aharonov-Bohm effect and measured a spin-dependent phase dislocation in the near-field due to scattering of surface plasmons from a topological defect. Finally, a spin-dependent dispersion splitting - Geometric Doppler Effect - was obtained in a structure consisting of a coupled thermal antenna array.