Nonlinear Optical Characterization with Instrumentation Development
Open Access
- Author:
- Murray, William
- Graduate Program:
- Electrical Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- October 07, 2020
- Committee Members:
- Zhiwen Liu, Dissertation Advisor/Co-Advisor
Zhiwen Liu, Committee Chair/Co-Chair
Timothy Joseph Kane, Committee Member
Xingjie Ni, Committee Member
Mauricio Terrones, Outside Member
Hans Hallen, Special Member
Kultegin Aydin, Program Head/Chair - Keywords:
- Ultrafast
Nonlinear Optics
Two-Dimensional Materials
NSOM
Near-field
Near-field Scanning Optical Microscopy
Spectroscopy
Microscopy
Instrumentation
Autocorrelation
Nanotechnology
Wearables - Abstract:
- Novel material discovery and innovative instrumentation development is a fundamental ebb and flow of technological innovation. Nonlinear optics, in particular, is a field which has benefitted greatly from both the continual discovery of novel materials and instrumentation advancement. However, silica and silicon based photonic systems, which still dominate the majority of visible and near-infrared photonic devices, inherently lack direct band gaps and their crystal symmetry limits second-order optical nonlinearity. In order to advance next generation nonlinear system-on-a-chip devices, other materials must be incorporated which intrinsically possess a second-order nonlinear susceptibility. Furthermore, to minimize propagating wave perturbation, these materials must also be thin. Two-dimensional transition metal dichalcogenides (TMDs), a class of atomically thin materials, a monolayer of which possesses direct band-gaps have been shown to possess an extraordinarily large second-order nonlinear susceptibility on the order of nm/V, making them ideal candidates for novel nonlinear photonic devices. This dissertation covers both the nonlinear optical characterization of monolayer TMDs to prove practicality and flexibility for nonlinear photonic devices, along with instrumentation developed to perform nonlinear optical characterization in the near-field; ultimately leading to a semi-turnkey near-field scanning optical microscope (NSOM) with novel nonlinear optical characterization capabilities, and a portable smartphone operated autocorrelator. First, a brief introduction is provided in Chapter 1. Following this, Chapter 2 discusses the robustness of second harmonic generation (SHG) in monolayer TMDs with various growth and post-synthesis defects, as well as under aqueous and ambient environmental conditions. Further, we present a broad-band analysis of the second-order nonlinear susceptibility in monolayer TMDs and the ability to engineer this second-order nonlinear susceptibility in monolayer TMDs. We conclude Chapter 2 by demonstrating the ability to utilize the tensorial property of SHG for characterizing crystalline space groups in atomically thin materials. Chapter 3 extends from the far-field into the near-field through the construction and implementation of a custom-designed near-field scanning optical microscope (NSOM). We present near-field microscopy results of SHG in monolayer TMDs before the NSOM system upgrade, the consequent redesign, and super-resolution near-field nonlinear microscopy of 120 nm spatial resolution in monolayer TMDs using our redesigned and semi-turnkey instrument. We expand upon near-field nonlinear microscopy in monolayer TMDs and demonstrate the ability to resolve temporal near-field ultrafast laser pulse information through SHG colinear frequency resolved optical gating (SHG-cFROG). We demonstrate that this technique does not suffer from any unexpected near-field pulse degradation, and thus can potentially be used for scanning ultrafast near-field second harmonic optical microscopy (SUNSHOM) in any organic or inorganic nanomaterials. In Chapter 4, a novel low-cost, fully battery-powered, smartphone operated wireless autocorrelator is developed and demonstrated. This autocorrelator provides the capability to measure lasers of wavelength 600 nm<λ_p<1150 nm, and a bandwidth of 50 fs < FWHM < 40 ps. Further, this autocorrelator is demonstrated to be controlled wirelessly via Bluetooth through an iPhone app. Chapter 5 explores low-cost, wireless optical device functionality in the biomedical realm through a wearable chloridometer. We investigate sweat collection through microfluidic devices fabricated via 3D printed molds, and point-of-care diagnostics for cystic fibrosis (CF) via a wearable bio-optical chloridometer. Finally, Chapter 6 summarizes this dissertation and explores both new applications of nonlinear optical devices using monolayer TMDs and new NSOM probe beyond a tapered optical fiber, such as metamaterials.