Date of Award

Spring 1-1-2017

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Juliet Gopinath

Second Advisor

Scott Diddams

Third Advisor

Thomas Schibli

Fourth Advisor

Wounjhang Park

Fifth Advisor

Robert McLeod

Abstract

The chalcogenide glass, Ge28Sb12Se60, is a promising material platform for compact, low-threshold nonlinear optical devices operating in the near- to mid-infrared. It is particularly attractive given its wide range of transparency, large Kerr coefficient, and relatively weak multi-photon absorption. The nonlinear optical properties of Ge28Sb12Se60 were investigated in bulk and waveguide forms, over a range of wavelengths from 1.0 to 3.5 μm. From z-scan measurements at 1.03 µm, using circularly polarized, 200 fs pulses at 374 kHz, bulk Ge28Sb12Se60 glass was found to have a nonlinear refractive index ~130 times that of fused silica and a two-photon absorption coefficient of 3.5 cm/GW. Ge-Sb-Se waveguides and microresonators were designed and characterized, laying groundwork for the development of efficient, compact nonlinear devices such as frequency combs and optical switches. In particular, single-mode Ge-Sb-Se strip waveguides, fabricated by photo- or e-beam lithography, followed by thermal evaporation and lift-off, were demonstrated with average propagation losses of 11.8 dB/cm at 1.03 µm and 4.0-6.1 dB/cm at 1.55 µm. Nonlinear optical waveguides were characterized with measurements of spectral broadening and intensity-dependent transmission, revealing a large measured nonlinear figure of merit of 5.2±1.6 at 1.55 µm. Hybrid chalcogenide-silica wedge microresonators were characterized from 1500-1630 nm, with loaded quality factors up to 1.5x105 and thermal resonant shifts ~60.5 pm/˚C. Finally, planar chalcogenide-based ring resonators were designed for operation at 1.55 and 3.5 µm, simulating dispersion and optimizing waveguide dimensions for maximum four-wave mixing conversion efficiency. Ring resonators with 6- and 20-µm radii were demonstrated with intrinsic quality factors of 1-2x104 and 8.3x104, respectively.

Available for download on Wednesday, February 28, 2018

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