Scanning electron microscope, X-ray diffraction and photoluminescence measurements were conducted on Be(x)Zn(1−x)O nanowires prepared by electrochemical and hydrothermal deposition to study their morphology, structure and optical properties. The bowing parameter for nanowires prepared by electrochemical and hydrothermal deposition was found to be 4.8 eV and 3.6 eV, respectively. It was observed that for electrochemical deposition, it is more difficult for Be(2+) to incorporate in the crystal lattice than Zn(2+). The electrochemical deposited samples exhibited stronger deep level emissions, indicating a higher density of deep level states. A home-made Optically Stimulated Luminescence (OSL) system was successfully constructed and calibrated with Al2O3:C and BeO. The OSL lifetime measurements on electrochemical deposited samples showed there were measurable OSL signals even on 500 nm long Be(x)Zn(1−x)O nanowires. The lifetimes of these OSL signals were found to decrease with increasing Be concentration. Be(x)Zn(1−x)O nanowires show considerable promise as new OSL materials.

This thesis aims at both developing highly nonlinear Aluminum Gallium Arsenide waveguides(AlGaAs) and demonstrating all-optical wavelength conversion via cross-phase modulation in AlGaAs waveguides at telecommunications wavelengths. This work covers waveguide design, device fabrication, device characterization and system work.

Scanning electron microscope, X-ray diffraction and photoluminescence measurements were conducted on Be(x)Zn(1−x)O nanowires prepared by electrochemical and hydrothermal deposition to study their morphology, structure and optical properties. The bowing parameter for nanowires prepared by electrochemical and hydrothermal deposition was found to be 4.8 eV and 3.6 eV, respectively. It was observed that for electrochemical deposition, it is more difficult for Be(2+) to incorporate in the crystal lattice than Zn(2+). The electrochemical deposited samples exhibited stronger deep level emissions, indicating a higher density of deep level states. A home-made Optically Stimulated Luminescence (OSL) system was successfully constructed and calibrated with Al2O3:C and BeO. The OSL lifetime measurements on electrochemical deposited samples showed there were measurable OSL signals even on 500 nm long Be(x)Zn(1−x)O nanowires. The lifetimes of these OSL signals were found to decrease with increasing Be concentration. Be(x)Zn(1−x)O nanowires show considerable promise as new OSL materials.

This thesis presents designs and fabrication algorithms for 3D photonic band gap (PBG) material synthesis and embedded optical waveguide networks. These designs are suitable for large scale micro-fabrication using optical lithography methods. The first of these is a criss-crossing pore structure based on fabrication by direct photo-electrochemical etching in single-crystal silicon. We demonstrate that a modulation of the pore radius between pore crossing points leads to a moderately large PBG. We delineate a variety of PBG architectures amenable to fabrication by holographic lithography. In this technique, an optical interference pattern exposes a photo-sensitive material, leading to a template structure in the photoresist whose dielectric-air interface corresponds to an iso-intensity surface in the exposing interference pattern. We demonstrate PBG architectures obtainable from the interference patterns from four independent beams. The PBG materials may be fabricated by replicating the developed photoresist with established silicon replication methods. We identify optical beam configurations that optimize the intensity contrast in the photoresist. We describe the invention of a new approach to holographic lithography of PBG materials using the diffraction of light through a three-layer optical phase mask (OPM). We show how the diffraction-interference pattern resulting from single beam illumination of our OPM closely resembles a diamondlike architecture for suitable designs of the phase mask. It is suggested that OPML may both simplify and supercede all previous optical lithography approaches to PBG material synthesis. Finally, we demonstrate theoretically the creation of three-dimensional optical waveguide networks in holographically defined PBG materials. This requires the combination of direct laser writing (DLW) of lines of defects within the holographically-defined photoresist and the replication of the microchip template with a high refractive index semiconductor such as silicon. We demonstrate broad-band (100-200~nm), single-mode waveguiding in air, based on the light localization mechanism of the PBG as well as sharp waveguide bends in three-dimensions with minimal backscattering. This provides a basis for broadband 3D integrated optics in holographically defined optical microchips.

The structure and structural dynamics of hydrogen bonded liquids were studied experimentally and theoretically with coherent two-dimensional infrared (2DIR) spectroscopy. The resonant intermolecular interactions within the fully resonant hydrogen bond networks give access to spatial correlations in the dynamics of the liquid structures. New experimental and theoretical tools were developed that significantly reduced the technical challenges of these studies. A nanofluidic flow device was designed and manufactured providing sub-micron thin, actively stabilized liquid sample layers between similarly thin windows. A simulation protocol for nonlinear vibrational response calculations of disordered fluctuating vibrational excitons was developed that allowed for the first treatment of resonant intermolecular interactions in the 2DIR response of liquid water. The 2DIR spectrum of the O-H stretching vibration of pure liquid water was studied experimentally at different temperatures. At ambient conditions the loss of frequency correlations is extremely fast, and is attributed to very efficient modulations of the two-dimensional O-H stretching vibrational potential through librational motions in the hydrogen bond network. At temperatures near freezing, the librational motions are significantly reduced leading to a pronounced slowing down of spectral diffusion dynamics. Comparison with energy transfer time scales revealed the first direct proof of delocalization of the vibrational excitations. This work establishes a fundamentally new view of vibrations in liquid water by providing a spatial length scale of correlated hydrogen-bond motions. The linear and 2DIR response of the amide I mode in neat liquid formamide was found to be dominated by excitonic effects due to largely delocalized vibrational excitations. The spectral response and dynamics are very sensitive to the excitonic mode structure and infrared activity distributions, leading to a pronounced asymmetry of linear and 2DIR line shapes. This was attributed to structurally different species in the liquid characterized by their degree of medium range structural order. The response is dominated by energy transfer effects, sensitive to time-averaged medium range structural order, while being essentially insensitive to structural dynamics. This work is the first to recognize the importance of energy transfer contributions to the 2DIR response in a liquid, and provides additional proof of the well-structured character of liquid formamide.

A new laser ablation mechanism of liquid water based on recent insights into its hydrogen bond dynamics has been studied and several applications of the ablation demonstrated. The mechanism, termed as Impulsive Heat Deposition through Vibrational Excitations (IHDVE), is based on the ability of the hydrogen bond network of water to rapidly thermalize vibrational O-H stretch excitations on a time scale of several picoseconds even for excitation intensities that are large enough to bring excited volumes far into the supercritical region. In this way, by using vibrationally resonant picosecond infrared laser pulses with sufficient energy, it is possible to drive ultrafast phase transitions in the excited water volume leading to a rapid and efficient ablation process of water and water rich targets with minimum perturbation of solute molecules of interest. The physics behind the IHDVE ablation process is outlined and the benefits of the IHDVE ablation are demonstrated for two important applications of tissue cutting and mass spectrometry of biomolecules. Finally, the development of two high power infrared laser systems suitable for the practical implementation of IHDVE is presented.

This thesis focuses on the ultrafast isomerization reaction of retinal in both rhodopsin and bacteriorhodopsin, examples of sensory and energy transduction proteins that exploit the same photoactive chromophore for two very different functions. In bacteriorhodopsin, retinal isomerizes from an all-trans to 13-cis conformation as the primary event in light- driven proton pumping. In the visual pigment rhodopsin, the retinal chromophore isomerizes from an 11-cis to all-trans geometry as the primary step leading to our sense of vision. This diversity of function for nominally identical systems raises the question as to just how optimized are these proteins to arrive at such drastically different functions? Previous work has employed transient absorption spectroscopy to probe retinal protein photochemistry, but many of the relevant electronic and nuclear dynamics of isomerization are masked by inhomogeneous broadening effects and strong spectral overlap between reactant and photoproduct states. This work exploits the unique properties of two-dimensional photon echo spectroscopy to deconvolve inhomogeneous broadening and spectral overlap effects and fully reveal the dynamics that direct retinal isomerization in proteins. In bacteriorhodopsin, vibrational coupling to the reaction coordinate results in a surface crossing event prior to the conventional conical intersection associated with isomerization to the J intermediate. In rhodopsin, however, a similarly early vibrationally-mediated barrier crossing event is observed, resulting in spectral signals consistent with the known photoproduct state appearing an order of magnitude faster than determined from conventional transient absorption measurements. The competing overlapping spectral signals that obscured the initial dynamics when probed with transient absorption spectroscopy are now clearly resolved with two-dimensional photon echo spectroscopy. These experiments illustrate the critical role of the protein in directing the outcome of retinal photochemistry. The protein controls the reaction pathway through steric interactions between the binding pocket and the retinal chromophore, the result of which directly sets the isomerization coordinate and indirectly controls the vibrational coupling to the reaction coordinate based on the local retinal structure. The new insight from this work is the extraordinary degree of selective vibrational coupling involved in directing the isomerization reaction in retinal proteins.

This thesis focuses on the ultrafast isomerization reaction of retinal in both rhodopsin and bacteriorhodopsin, examples of sensory and energy transduction proteins that exploit the same photoactive chromophore for two very different functions. In bacteriorhodopsin, retinal isomerizes from an all-trans to 13-cis conformation as the primary event in light- driven proton pumping. In the visual pigment rhodopsin, the retinal chromophore isomerizes from an 11-cis to all-trans geometry as the primary step leading to our sense of vision. This diversity of function for nominally identical systems raises the question as to just how optimized are these proteins to arrive at such drastically different functions? Previous work has employed transient absorption spectroscopy to probe retinal protein photochemistry, but many of the relevant electronic and nuclear dynamics of isomerization are masked by inhomogeneous broadening effects and strong spectral overlap between reactant and photoproduct states. This work exploits the unique properties of two-dimensional photon echo spectroscopy to deconvolve inhomogeneous broadening and spectral overlap effects and fully reveal the dynamics that direct retinal isomerization in proteins. In bacteriorhodopsin, vibrational coupling to the reaction coordinate results in a surface crossing event prior to the conventional conical intersection associated with isomerization to the J intermediate. In rhodopsin, however, a similarly early vibrationally-mediated barrier crossing event is observed, resulting in spectral signals consistent with the known photoproduct state appearing an order of magnitude faster than determined from conventional transient absorption measurements. The competing overlapping spectral signals that obscured the initial dynamics when probed with transient absorption spectroscopy are now clearly resolved with two-dimensional photon echo spectroscopy. These experiments illustrate the critical role of the protein in directing the outcome of retinal photochemistry. The protein controls the reaction pathway through steric interactions between the binding pocket and the retinal chromophore, the result of which directly sets the isomerization coordinate and indirectly controls the vibrational coupling to the reaction coordinate based on the local retinal structure. The new insight from this work is the extraordinary degree of selective vibrational coupling involved in directing the isomerization reaction in retinal proteins.

This thesis reports on ultrafast linear and nonlinear optical probing of nanometer thick films. Exfoliated graphene and few-layer graphite are probed through optical second harmonic generation (SHG) with 800 nm, 150 fs pulses. Samples of varying thickness from 1 carbon layer to bulk graphite are deposited onto an oxidized silicon substrate. SHG measurements are taken as a function of azimuthal rotation angle of the films. It is found that the SHG from graphene is much weaker than that from bilayer graphene, and has a qualitatively different azimuthal pattern. As the sample thickness increases from bilayer graphene to bulk graphite, the SHG yield generally decreases. Both of these effects are explained in terms of the symmetry of graphene and graphite, and modeled using multilayer optical transfer matrices, and an identical set of nonlinear susceptibility tensor elements for the front and back surfaces. These tensors are independent of sample thickness. MnAs films of 150 and 190 nm thickness on (001)GaAs are optically excited with 775 nm, 200 fs pump pulses. Specular SHG at 388 nm and first order optical diffraction at ∼ 400 nm are used to probe the samples on timescales up to 2 μs. It is found that the SHG probes the temperature-dependent, spatially averaged, surface strain. This strain reaches a maximum deviation in ∼ 6–100 ps after optical excitation depending on the pump fluence and initial temperature. The strain then recovers in hundreds of picoseconds, a timescale consistent with heat diffusion. The optical diffraction probes the first Fourier component of the paramagnetic–ferromagnetic stripes inherent to MnAs films in the 10–40◦C temperature range. After optical excitation, the diffraction data show highly nonthermal behaviour in the MnAs films. If a sample is excited from the coexistence phase, the diffraction signal shows decaying oscillations with a period of ∼ 335±4 (408±4) ps for the 150 (190) nm films; this is consistent with the release of a standing acoustic wave. Decay occurs on a timescale of ∼ 2 ns consistent with local diffusion through the films. The stripes are restored on a timescale of hundreds of nanoseconds, with a temporal behavior consistent with a diffusion process, possibly thermal in origin.

This thesis reports on ultrafast linear and nonlinear optical probing of nanometer thick films. Exfoliated graphene and few-layer graphite are probed through optical second harmonic generation (SHG) with 800 nm, 150 fs pulses. Samples of varying thickness from 1 carbon layer to bulk graphite are deposited onto an oxidized silicon substrate. SHG measurements are taken as a function of azimuthal rotation angle of the films. It is found that the SHG from graphene is much weaker than that from bilayer graphene, and has a qualitatively different azimuthal pattern. As the sample thickness increases from bilayer graphene to bulk graphite, the SHG yield generally decreases. Both of these effects are explained in terms of the symmetry of graphene and graphite, and modeled using multilayer optical transfer matrices, and an identical set of nonlinear susceptibility tensor elements for the front and back surfaces. These tensors are independent of sample thickness. MnAs films of 150 and 190 nm thickness on (001)GaAs are optically excited with 775 nm, 200 fs pump pulses. Specular SHG at 388 nm and first order optical diffraction at ∼ 400 nm are used to probe the samples on timescales up to 2 μs. It is found that the SHG probes the temperature-dependent, spatially averaged, surface strain. This strain reaches a maximum deviation in ∼ 6–100 ps after optical excitation depending on the pump fluence and initial temperature. The strain then recovers in hundreds of picoseconds, a timescale consistent with heat diffusion. The optical diffraction probes the first Fourier component of the paramagnetic–ferromagnetic stripes inherent to MnAs films in the 10–40◦C temperature range. After optical excitation, the diffraction data show highly nonthermal behaviour in the MnAs films. If a sample is excited from the coexistence phase, the diffraction signal shows decaying oscillations with a period of ∼ 335±4 (408±4) ps for the 150 (190) nm films; this is consistent with the release of a standing acoustic wave. Decay occurs on a timescale of ∼ 2 ns consistent with local diffusion through the films. The stripes are restored on a timescale of hundreds of nanoseconds, with a temporal behavior consistent with a diffusion process, possibly thermal in origin.