Doctor of Philosophy Oral Defense: Indra Ghimire

DateApril 9, 2021
Time2:00 - 4:00 pm
Doctor of Philosophy Oral Defense

Indra Ghimire

Zhenrong Zhang, Ph.D. - Advisor

Advanced light manipulation and waveguiding in plasmonic nanostructured optical fibers

Conventional optical fibers are well-known for their efficient light guiding mechanism. However, the dielectric properties of core and cladding materials (e.g.- doped silica and silica glasses) limit the functionality of optical fibers. Therefore, the optical properties of the fibers, such as phase, polarization state, amplitude, mode profile are fixed and cannot be altered once after the fiber drawing fabrication. The advent of new fabrication technologies for optical nanostructures such as plasmonics and metasurfaces allows us to overcome these limitations by tailoring those optical properties for advanced light manipulation.

In this dissertation, I will be discussing two main projects on the integration of plasmonic nanostructures into optical fibers during my graduate research. In attempts to modify the optical properties of optical fibers and create new functionalities, advanced nanophotonics has been utilized. One of the projects consists of plasmonic excitation that utilizes asymmetric cross-typed nanoslit plasmonic arrays on optical fiber end face for developing a polarization-dependent in-fiber color filter with a transmission efficiency of ~ 70 % in the telecommunication wavelength range. The nanostructures on the optical fiber facet were fabricated with a focused ion beam (FIB) milling technique in the dual-beam focused ion beam scanning electron microscopy (FIB-SEM). Berry-phase nano-antenna metasurface integrated into single-mode fiber as in-fiber metalens will also be briefly discussed. In the other project, the advanced integration of nanoscale plasmonic circuit and optical fiber will be presented. Yagi-Uda antenna-assisted plasmonic waveguide has been utilized to couple light from the core of the optical fiber to the surface plasmon polariton on the plasmonic slot waveguides that are fabricated directly on the end face of the optical fiber. We show efficient light coupling from the optical fiber to the plasmonic waveguide mode and further demonstrations on complex nano-circuits such as multi-waveguide channels, polarization-dependent splitters, and optical directional coupler in the facet of polarization-maintaining fiber will also be presented. Our work of integrating plasmonic circuits and nanostructures on optical fiber opens up paths for the realization of next generation in-fiber devices such as optical interconnectors, modulators, filters, and switches.

Meeting id: 842 4548 8498

Passcode: 571904
PublisherDepartment of Physics
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