M.Sc Thesis

M.Sc StudentOstrovsky Evgeny
SubjectNano Scale Control over Optical Singularities
DepartmentDepartment of Electrical and Computer Engineering
Supervisor PROF. Guy Bartal
Full Thesis textFull thesis text - English Version


Surface Plasmon Polaritons (SPP) are electro-magnetic (EM) waves propagating along metal-insulator interfaces with unique properties that enable field concentration into deep sub-wavelength volumes, far beyond the well-known diffraction limit first describe by Abbe. This ability to highly confine optical fields has driven rapid expansion in research and emerging technologies in recent years, utilizing the ability of plasmonic devices to generate, guide, modulate and detect light using nanoscale structures. These remarkable capabilities have the potential for significant advances and future applications such as optical signal processing, nanoscale optical devices, super-resolution optical microscopy, non-linear optics and optical metamaterials.

Being EM fields, SPPs possess many properties such as phase, polarization, etc. Points in such EM fields, where at least one of these properties is singular, i.e. undefined, are called Optical singularities.

Optical singularities have attracted much interest in the past decades, enabling advancements in nano-manipulation, bio-sensing, and quantum optics, owing to their ability to carry and transfer angular momentum on the nano scale. Optical vortices (OVs), in this respect, are phase singularities useful for many applications, such as particle trapping and manipulation, optical communication, and super-resolution. Vectorial OVs also exhibit polarization singularities, known as C-points, which have been used in recent years to control emission from quantum emitters

In this thesis, we present the design, implementation and characterization of  continuous nanoscale spatial control over optical singularities, both phase and polarization,on a metal-air interface. The control is unique as it does merely achieved by varying the polarization state of the light exciting surface plasmon polaritons through a spiral slit. We demonstrate our method using phase-resolved near-field scanning optical microscopy (S-NSOM) both amplitude and phase measurements which are backed up with simulations.

Such control over optical singularities opens up exciting possibilities for light in two dimensions, ranging from new light-matter interactions on a chip to efficiently controlled nanomotors.