M.Sc Thesis

M.Sc StudentBerkovitch Nikolai
SubjectDipole and Surface Plasmons in Metallic Nanostructures
DepartmentDepartment of Physics
Supervisors PROFESSOR EMERITUS Stephen Lipson
PROF. Meir Orenstein
Full Thesis textFull thesis text - English Version


Surface Plasmon Polaritons (SPP) are electromagnetic excitations that propagate at the interface between a dielectric having positive dielectric constant and a metal having a negative dielectric constant. SPP evanescently decay into both media thus enabling the optical mode to be confined on the nano-scale. 

We investigated theoretically and experimentally plasmonic slot waveguides having nanometric dimensions. In the theoretical part we showed a new family of discrete modes in asymmetrical waveguides with losses related to asymmetrical plasmonic slots. Such modes do not exist in a pure lossless case. Experimentally slot waveguides were fabricated by Focused Ion Beam (FIB) on a thin (80nm) and thick (900nm) Au layer with Si substrate and measured using Near field Scanning Optical Microscope (NSOM) at wavelength λ=1.55μm.

Particle plasmons and their interactions were investigated for small metallic nanoparticles. Theoretical predictions of the plasmon resonances in small metallic particles and the dipole-dipole interactions between particles were experimentally confirmed by analyzing far field transmission spectra. The sample, a particle array 100x100μm with 100nm Au particles and 50nm spacing between particles was prepared using Focused Ion Beam (FIB).

We developed methods of fabrication of metallic nanostructures using Focused Ion Beam (FIB) and Electron Beam writing (E-beam). For the FIB processing we optimized methods to produce structures as small as 100nm and we optimized the etching time of the large arrays of nanoparticles to less than half an hour. For E-beam writing we found improved the contrast of the alignment marks which enabled us to fabricate large hybrid optical circuits with micron and nano structures combined together.