Keywords

Chalcogenides, Femtosecond lasers, Glass, Optofluidics

Abstract

Femtosecond laser direct writing (FLDW) is a versatile process that uses focused femtosecond pulses to modify the physical structure of a material, which can result in a shift of optical properties such as the linear and nonlinear refractive index. If the photon energy of the femtosecond pulses lies below the material bandgap, nonlinear absorption rather than linear absorption becomes the dominant mechanism of energy transfer to the material. In this manner, a focused femtosecond pulse train can be used to fabricate functional features such as optical waveguides, diffractive optical elements, or micro-fluidic elements within the volume of a transparent medium. In this dissertation, the utility of femtosecond laser processing as a fabrication technique of optical and micro-fluidic elements in chalcogenide glasses is explored. The photo-induced modifications of optical and chemical parameters of new germanium-based Chalcogenide glasses in both bulk and thin-film form are characterized for the first time and the impact of material composition and laser fabrication parameters are discussed. The glasses are found to display an increase in volume, a decrease of the linear optical refractive index, and an increase of the nonlinear refractive index when exposed to femtosecond laser pulses. A model based on avalanche ionization and multi-photon ionization is used to describe the highly nonlinear absorption of laser light in the material and correlate the photo-induced modifications to the electron density generated during irradiation. The magnitude of the induced photomodification is shown to be dependent on laser parameters such as laser dose and repetition rate. The fabrication of microfluidic elements through both direct ablation and the preferential etching of photo-modified regions is also explored. Finally, the integration of both optical elements and fluidic elements fabricated by FLDW into a single substrate is discussed. iv TABLE OF CONT

Notes

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Graduation Date

2010

Semester

Spring

Advisor

Richardson, Martin

Degree

Doctor of Philosophy (Ph.D.)

College

College of Optics and Photonics

Format

application/pdf

Identifier

CFE0002978

URL

http://purl.fcla.edu/fcla/etd/CFE0002978

Language

English

Release Date

May 2010

Length of Campus-only Access

None

Access Status

Doctoral Dissertation (Open Access)

Subjects

Dissertations, Academic -- Optics and Photonics,Optics and Photonics -- Dissertations, Academic

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