Towards the harnessing of the structural properties of optical fiber

The post-fabrication internal structure of optical fiber defines the operational limitations for a given draw across the entire range of applications. While more traditional fabrication methods have greatly matured from thorough investigation of nearly every aspect of fiber, more recent, novel, and promising draw techniques have yet to receive the same treatment. While the discussion will be limited to optical fiber defects and nonlinear processes, there are many empirical quantities which are assumed from bulk glass values that may prove inadequate as fabrication techniques forge ahead. Both investigations herein focus on all-glass fibers drawn from the molten core method (MCM). The first of which, is a thorough examination of a previously unobserved visible defect luminescence from near-infrared (NIR) pumping in a nominally passive barium fluorosilicate (BFS) fiber. This emission is profoundly unique across fiber defects due to the nonlinear nature of its absorption and emission and relatively low pump power requirement at room temperature. Absorption, photoluminescent (PL) emission, and excitation (PLE) spectra ranging across the ultraviolet (UV) to NIR combined with radiative lifetime decay measurements, Raman spectroscopy, magnetization curves, and temperature dependence results were taken to both characterize the defect and pinpoint its origin within the drawn glass fiber. The temperature dependence was sensitive enough to be a capable optical thermometer. Further investigation of other similarly drawn alkaline earth fluorosilicates (AEFs) and alumino-fluorosilicates (AEAFs) under similar conditions as the BFS fiber and with additional high power pulsed excitation were completed to extend the discussion on the roles of the alkaline earth and alumina precursors on the drawn fiber. The initial investigation into second harmonic generation from simple, <1 W, continuous wave (CW) pumping from MCM fibers was completed in an effort to determine if the nano-scale phase separation has provided a feasible all-fiber approach to the χ(2) process. While the defect luminescence may be ascribed to two-photon absorption — a χ(3) interaction — any observation of SHG in fiber should require extreme amounts of power to offset the vanishingly small susceptibility from the centrosymmetric nature of amorphous glass.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Electrical & Computer Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2024

Author dc:creator

• Pietros, Alexander Robel

Contributors dc:contributor

• Dragic, Peter D
• Ballato, John
• Bogdanov, Simeon I
• Cavillon, Maxime
• Choquette, Kent D

• Optical Fiber
• Glass Defects
• Luminescent Defects

Statement dc:rights

• Copyright 2024 Alexander Pietros

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/127505

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F127505