טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentPlotnik Yonatan
SubjectEigenmodes of Complex Optical Structures and Topological
Photonics
DepartmentDepartment of Physics
Supervisor ? 18? Mordechai Segev
Full Thesis textFull thesis text - English Version


Abstract

During my doctorate I investigated eigenmodes of electromagnetic waves in optical systems. Since wave phenomena are universal and not platform dependent, the results reached are applicable to many wave systems, such as water waves, electromagnetic waves, sound waves, etc.. My work was done in the paraxial regime, where light travels mostly in parallel to a certain axis (marked  ), and the evolution of the wave is governed by the paraxial wave equation. In this regime, the paraxial wave equation is of the same form as the famous Schrödinger equation with the difference being that the coordinate z plays the role of time. This means that the results obtained in the research are also applicable to quantum particles.

An eigenmode of the optical system is thus an electromagnetic wave with a structure that does not change as a function of z, but only accumulates phase. In my research, I investigated systems that have unique eigenmodes with fascinating, and sometimes unexpected features:

-          We demonstrated experimentally for the first time the existence of “bound states in the continuum”, i.e. modes that are bound in space even though their frequency is beyond a threshold value above which the modes tend to extend to infinity (so called “extended states”).

-          We measured the edge modes (modes residing on the edge of the structure) of photonic graphene, which is a waveguide array arranged in the shape of a honeycomb lattice, and found a new unexpected edge mode.

-          We demonstrated the first optical topological insulator by, demonstrating unidirectionally traveling topologically protected edge modes. This is also the first experimental demonstration of a Floquet topological insulator in any system in nature.

-          We demonstrated a new optical platform to observe the Rashba effect using gauge field engineering.

These results only sparked more ideas for future projects, which will hopefully be the makings of future PhD theses.