Resonant Nanostructures for Optical Waveguide Integration and Metasurfaces

Abstract

Integrated nano-optics and nano-photonics have been very hot topics in the last two decades, and they play very important roles in telecommunications, optical interconnectors, integrated sensing devices, just to name a few. Traditionally, integrated photonic crystals, Mach Zehnder waveguides interferometers, ring resonators, gratings are the key elements for integrated photonic circuits, however, they are bulky and there is a room to decrease further the functional areas to make more compact integrated photonic devices. Due to their ability to confine light in sub-wavelength volumes plasmonic nanoparticles and nanoantennas can serve as a fundamental link between electronic and photonic circuits, as they can bridge large size mismatch between the electronic and optical wave function. Thus, plasmonic elements can be utilized to increase the integration density and performance of active and passive photonic devices, as well as to include new functionalities and concepts for photonic chips. Therefore, our goal is to design subwavelength functional areas by utilizing plasmonic meta atoms to manipulate both farfield and localized light and integrate these plasmonic functional areas into dielectric optical waveguides. However, plasmonic materials suffer from their intrinsic absorption. All-dielectric nanoantennas, on the other hand, exhibit high radiation efficiencies, but the lower field confinement and enhancement which also reduce coupling efficiencies.

Therefore, this thesis is mainly focused on exploiting the novel applications in integrated photonic devices based on applying the advantages of plasmonic and dielectric nanoantennas, respectively. The topics include the integration of plasmonic nanoantennas on silicon waveguides, such as the spectral band splitting by using a single Fano nanoantenna, and polarization demultiplexing by utilizing a dragon fly shape nanoantenna. Furthermore, this thesis also contains hybrid and all dielectric metasurfaces in localized light manipulating, biosensing, and opto-mechanics applications.