Stratified Fiber-Resonator: Fabrication, Characterization and Potential Applications

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Naqvi, Z. (2017). Stratified Fiber-Resonator: Fabrication, Characterization and Potential Applications. Unc Charlotte Electronic Theses And Dissertations.
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Abstract

Whispering Gallery Mode Resonators (WGMR) are compact, monolithic resonators used for photonic applications. Controlling the properties of WGM while keeping the geometry simple is desired to improve their performance, especially for sensing and non-linear interactions. One way to achieve this is by coating the WGMR with a layer of certain refractive index profile, which has been shown to modify the effective optical potential thus allowing control of the WGM field. This dissertation focusses on coating of an optical fiber with single or multiple thin films with precise control of thickness and refractive index. Transfer matrix method is applied to study the effect of coated films on the mode structures and field profiles of fiber WGM. For small layer thickness the mode shifts to the periphery while for large thicknesses waveguide modes are found and coupling is observed for multiple layers. Fibers are coated uniformly in a commercial PECVD instrument modified to enable continuous rotation of fibers. Mie scattering of coated fibers is utilized to extract refractive index and thickness of coated thin films, which is otherwise challenging due to non-flat topology and small size of the fibers. It is found that rotation leads to higher deposition rate and refractive index of films, compared to those deposited on a static wafer. These differences are demonstrated to depend on the rotation speed, opening interesting dynamic tuning capabilities. Further, fibers with Bragg layers are fabricated and their scattering analyzed. It is found that judicious choice of film thickness can drastically modify scattering signatures of Bragg fibers. A ray model taking into account photonic bandgap of Bragg layers is proposed to successfully explain these anomalous features.

Details
Author

Naqvi, Zeba

Title

Stratified Fiber-Resonator: Fabrication, Characterization and Potential Applications

Physical Description

1 online resource (160 pages) : PDF

Date

2017

Degree Granting Institution

University of North Carolina at Charlotte

Abstract

Whispering Gallery Mode Resonators (WGMR) are compact, monolithic resonators used for photonic applications. Controlling the properties of WGM while keeping the geometry simple is desired to improve their performance, especially for sensing and non-linear interactions. One way to achieve this is by coating the WGMR with a layer of certain refractive index profile, which has been shown to modify the effective optical potential thus allowing control of the WGM field. This dissertation focusses on coating of an optical fiber with single or multiple thin films with precise control of thickness and refractive index. Transfer matrix method is applied to study the effect of coated films on the mode structures and field profiles of fiber WGM. For small layer thickness the mode shifts to the periphery while for large thicknesses waveguide modes are found and coupling is observed for multiple layers. Fibers are coated uniformly in a commercial PECVD instrument modified to enable continuous rotation of fibers. Mie scattering of coated fibers is utilized to extract refractive index and thickness of coated thin films, which is otherwise challenging due to non-flat topology and small size of the fibers. It is found that rotation leads to higher deposition rate and refractive index of films, compared to those deposited on a static wafer. These differences are demonstrated to depend on the rotation speed, opening interesting dynamic tuning capabilities. Further, fibers with Bragg layers are fabricated and their scattering analyzed. It is found that judicious choice of film thickness can drastically modify scattering signatures of Bragg fibers. A ray model taking into account photonic bandgap of Bragg layers is proposed to successfully explain these anomalous features.

Genre

doctoral dissertations

Subjects--Topics

Optics

Degree

Ph.D.

Keywords

Fiber
Microresonator
PECVD
WGM

Subject Area

Optical Science & Engineering

Advisor(s)

Her, Tsing-Hua

Committee Members

Farahi, Faramarz
Gbur, Greg
Egusa, Shunji
Smith, Stuart

Degree Note

Thesis (Ph.D.)--University of North Carolina at Charlotte, 2017.

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Rights Holder Information

Copyright is held by the author unless otherwise indicated.

Identifier

Naqvi_uncc_0694D_11509

Permalink

http://hdl.handle.net/20.500.13093/etd:1061