PhD Dissertation: Eesa Rahimi | Enerji-Minor

PhD Dissertation: Eesa Rahimi

PhD Dissertation: Eesa Rahimi

Dynamically Tunable Localized Surface Plasmons using VO2 Phase Transition

 

 

Eesa Rahimi
Mechatronics Engineering  PhD Dissertation, 2017

 

Thesis Jury

Prof. Kürşat Şendur

Assoc. Prof. Ahmet Onat

Assoc. Prof. Burç Mısırlıoğlu

Assoc. Prof. Hakan Ertürk

Asst. Prof. Erdem  Öğüt

 

 

 

Date & Time: July 27th, 2017 –  10:00 AM

Place: FENS 2008

Keywords : Localized Surface Plasmons, Vanadium Dioxide Phase Transition, Femtosecond Pulse Shaping, Chimera States, Nano-Optical Antenna, Reflection Switchability

 

Abstract

 

The ability of plasmonic nanoparticles to tailor the electromagnetic spectrum enables many applications in science. The control of light with devices in practical applications require dynamic tunability of localized surface plasmons. Employing phase change materials in plasmonic structure enables it to respond to light dynamically depending the external stimulate. This study investigates the response in presence of vanadium dioxide (VO2) phase transition for numbers of novel and classic problems.  

 

To illustrate the significance of optical spectrum tunability by VO2 two important functionalities for the phenomenon have been introduced. In the first application, a compact and ultrathin plasmonic metasurface is suggested for an ultra-short pulse shaping of transmitted pulse based on linear filtering principle of electromagnetic wave. A Joule heating mechanism that is transparent for polarization of the optical pulse is proposed to control the thermal phase transition of the VO2 inside the metasurface to manipulate light spectrum. It is shown that the thin film stack can compress/expand the Gaussian pulse span up to 90% or change the polization and phase of passing light. It is demonstrated that the tunable optical filter can compensate real-time input carrier frequency shifts and pulse span variations to stabilize the output pulse. Second application is dedicated to the field of intrachip optical communication which shows how VO2 phase transition can effectively switch a communicating antenna on and off. A substantial directional gain switching is obtained by employing VO2 phase transition to alternate resonances of a Yagi-Uda antenna elements.

 

VO2 scattering functionality in absence of localized surface plasmons is studied to illustrate their promising performance in light reflection. Spherical core-shells embedded in a polymer host material are proposed to manipulate reflectivity at near-infrared regime based on the Mie scattering formulation and it is shown that up to 67 % of the incident power can be controlled by switching temperature in the structure of randomlly distributed nano-particles composite.

 

Finally the behavior of localized surface plasmon resonators is studied and chimera stats which are the concurrent combination of synchronous and incoherent oscillations in a set of identical oscillators is shown for the first time in the optical regime. The effect of coupling strength on the phase scape/synchronization of the spaser-based devised oscillators is investigated. It is shown that for the eight identical oscillator system, which are placed symmetrically over the perimeter of a circle, the array can be divided to several subgroups of  concurrent coherent and incoherent members. In this array strong coupling can force the array members to fully synchronize while weaker coupling demonstrates chimera states among the oscillators.