Epsilon-near-zero materials are an emerging class of nanophotonic materials which engender electromagnetic field enhancement and small phase variation due to their approximate zero permittivity. These quasi-static fields facilitate a number of unique optical properties such as supercoupling, subwavelength confinement, and enhanced light-matter interactions, which has made epsilon-near-zero media a rapidly expanding field of optical physics. Contemporary methods of realizing a system with zero permittivity rely on microwave cavities/waveguides or complex metal-dielectric metamaterials; however, both techniques require advanced fabrication and their operational wavelength is fixed relative to their geometric and optical parameters. It remains an open and substantial challenge to realize an epsilon-near-zero material at pertinent wavelengths, particularly near- and mid-infrared, with tunable/dynamic properties. The focus of this thesis is the exploration of transparent conducting oxides for the development of epsilon-near-zero nanophotonic phenomena and applications. Transparent conducting oxides have an inherent low permittivity, in addition to simple fabrication and tunable optical properties, making them exceptionally promising. Application of transparent conducting oxide films for highly confined modes, nonlinear/ultrafast optics, and strongly coupled systems are discussed.

One of the most promising devices to provide accurate measurement of the longitudinal bunch profile at the tens of femtosecond level is based on electro-optic techniques. In this thesis, a bunch profile monitor, based on electro-optic spectral decoding (EOSD), is currently developed for the CLIC Test Facility 3 at CERN. The monitor is optimised for bunch lengths over 3.5 ps with effective window of 16 ps, and sub-picosecond resolution. The measurement results from the EO monitor are compared with measurements by coherent transition radiation on a streak camera. The measurement on bunch charge dependence is studied. Timing resolution of the bunch profile monitor is studied in both theory and numerical calculation. This thesis summarises a frequency analysis approach of electro-optic effect based on $\chi^{(2)}$ frequency mixing process. From the theory analysed in frequency domain, a non-crossed polarization measurement includes all three of the probe laser background term, the linear term to Coulomb field and the quadratic term to Coulomb field. Three methods are induced based on this frequency analysis result to retrieve Coulomb field value which is emitted from electron beam. The measured 1.3 MV/m field strength agrees with calculation result. An experiment is designed to study the role of incident beam sizes and non-collinear incident beams in EO technique. Due to the phase matching process, the non-collinear angle of the incident beams induces a frequency dependent angular chirp in the beams emitted after the EO crystal. This frequency offset may lead to frequency loss in fibre coupling, and thus lead to bunch length broadening in a measurement for short electron bunch.

The main theme covered in this thesis is experimentalstudies of quantum dynamics and coherent control in homonuclearalkali diatomic molecules by ultrafast laser spectroscopy iththe implementation of pump-probe techniques. A series of experiments have been performed on the Rb2molecules in a molecular beam as well as in a thermal oven. Thereal-time molecular quantum dynamics of the predissociatingelectronically excited D(3)1Πu state of Rb2, which couples to/intersects several otherneighbouring states, is investigated using wavepackets. Thepredissociation of the D state, explored by this wavepacketmethod, arises from two independent states, the (4)3Σu+and (1)3∆u, for which the second corresponds to a much fasterdecay channel above a sharp energy threshold around 430 nm. Thelifetime of the D state above the energy threshold is obtained,τ ≈ 5 ps, by measuring the decay time of thewavepacket in a thermal oven. Further experimentalinvestigation performed in a molecular beam together withquantum calculations of wavepacket dynamics on the D state haveexplored new probe channels of wavepacket evolution: theD′(3)1Σu+ channel, which exhibits vibrational motionin a shelf state and the (4)3Σu+ channel, where direct build-up of thewavefunction is observed due to its spin-orbit oupling to the Dstate. The real-time quantum dynamics of wavepackets confined totwo bound states, A1Σu+(0u+) and b3Πu(0u+), have been studied by experiment andcalculations. It is shown that these two states are fullycoupled by spin-orbit interaction, characterised by itsintermediate strength. The intermediate character of thedynamics is established by complicated wavepacket oscillationatterns and a value of 75 cm-1is estimated for the coupling strength at thestate crossing. The experiments on the Li2molecule are performed by coherent control ofrovibrational molecular wavepackets. First, the Deutsch-Jozsaalgorithm is experimentally demonstrated for three-qubitfunctions using a pure coherent superposition of Li2rovibrational eigenstates. The function’scharacter, either constant or balanced, is evaluated by firstimprinting the function, using a phase-tailored femtosecond(fs) pulse, on a coherent superposition of the molecularstates, and then projecting the superposition onto an ionicfinal state using a second fs pulse at a specific delay time.Furthermore, an amplitude-tailored fs pulse is used to exciteselected rovibrational eigenstates and collision induceddephasing of the wavepacket signal, due to Li2-Ar collisions, is studied experimentally. Theintensities of quantum beats decaying with the delay time aremeasured under various pressures and the collisional crosssections are calculated for each well-defined rovibrationalquantum beat, which set the upper limitsfor ure dephasingcross sections. <b>Keywords:</b>Ultrafast laser spectroscopy, pump-probetechnique, predissociation, wavepacket, pin-orbit interaction,coherent control, (pure) dephasing

An algorithm for extracting event information from a Coulomb Explosion Imaging (CEI) position sensitive detector (PSD) is developed and compared with previously employed schemes. The PSD is calibrated using a newly designed grid overlay and validates the quality of the described algorithm. Precision calculations are performed to determine how best the CEI apparatus at The University of Waterloo can be improved. An algorithm for optimizing coincidence measurements of polyatomic molecules in CEI experiments is developed. Predictions of improved efficiency based on this algorithm are performed and compared with experiments using a triatomic molecule. Analysis of an OCS targeted CEI experiment using highly charged Argon ions to initiate ionization is performed. The resulting measurements are presented using a variety of visualization tools to reveal asynchronous and sequential fragmentation channels of OCS3+.

A comprehensive model for describing the fundamental mechanism dictating the interaction of ultrafast laser pulse with single crystalline silicon wafer is formulated. The need for establishing the feasibility of employing lasers of subpicosecond pulse width in Laser Induced Stress Waves Thermometry (LISWT) for single crystalline silicon processing motivated the work. The model formulation developed is of a hyperbolic type capable of characterizing non-thermal melting and thermo-elastoviscoplastic deformation as functions of laser input parameters and ambient temperature. A plastic constitutive law is followed to describe the complex elasto-viscoplastic responses in silicon undergoing Rapid Thermal Processing (RTP) annealing at elevated temperatures. A system of nine first-order hyperbolic equations applicable to describing 3-D elasto-viscoplastic wave motions in silicon is developed. The group velocities of certain selected frequency components are shown to be viable thermal indicators, thus establishing the feasibility of exploiting nanosecond laser induced propagating stress waves for the high-resolution thermal profiling of silicon wafers. Femtosecond laser induced transport dynamics in silicon is formulated based on the relaxation-time approximation of the Boltzmann equation. Temperature-dependent multi-phonons, free-carrier absorptions, and the recombination and impact ionization processes governing the laser model and carrier numbers are considered using a set of balance equations. The balance equation of lattice energy and equations of motion of both parabolic and hyperbolic types are derived to describe the complex thermo-elastoplastodynamic behaviors of the material in response to ultrafast laser pulsing. The solution strategy implemented includes a multi-time scale axisymmetric model of finite geometry and a staggered-grid finite difference scheme that allows both velocity and stress be simultaneously determined without having to solve for displacements. Transport phenomena initiated by femtosecond pulses including the spatial and temporal evolutions of electron and lattice temperatures, along with electron-hole carrier density, are found to be functions of laser fluence and pulse width. The femtosecond laser heating model that admits hyperbolic energy transport is shown to remedy the dilemma that thermal disturbances propagate with infinite speed. Non-thermal melting fluence is examined favorably against published experimental data. That it is feasible to explore femtosecond laser induced displacement and stress components for 1K resolution thermal profiling is one of the conclusions reached.

In this study, the characteristic properties of the ultrafast laser exhibit sufficiently in the application of RFOBIC and two-photon UV fluorescence. This laser can be used to measure photonic components with fast responding speed due to the ultrashort pulse and broad bandwidth which is RF bandwidths of greater than 1.8THz. we have demonstrated the use of a frequency-doubled femtosecond optical parametric oscillator in generating two-photon excitation that is equivalent to ultraviolet(UV) light with wavelength less than 300 nm. This capability allows observation of some amino acids and enables excitation that is only possible with wavelength in UVB range(290 nm-320 nm)

<p>The main theme covered in this thesis is experimentalstudies of quantum dynamics and coherent control in homonuclearalkali diatomic molecules by ultrafast laser spectroscopy iththe implementation of pump-probe techniques.</p><p>A series of experiments have been performed on the Rb2molecules in a molecular beam as well as in a thermal oven. Thereal-time molecular quantum dynamics of the predissociatingelectronically excited D(3)¹Πu state of Rb₂, which couples to/intersects several otherneighbouring states, is investigated using wavepackets. Thepredissociation of the D state, explored by this wavepacketmethod, arises from two independent states, the (4)³Σ_u⁺and (1)³∆_u, for which the second corresponds to a much fasterdecay channel above a sharp energy threshold around 430 nm. Thelifetime of the D state above the energy threshold is obtained,τ ≈ 5 ps, by measuring the decay time of thewavepacket in a thermal oven. Further experimentalinvestigation performed in a molecular beam together withquantum calculations of wavepacket dynamics on the D state haveexplored new probe channels of wavepacket evolution: theD′(3)1Σu+ channel, which exhibits vibrational motionin a shelf state and the (4)³Σu+ channel, where direct build-up of thewavefunction is observed due to its spin-orbit oupling to the Dstate.</p><p>The real-time quantum dynamics of wavepackets confined totwo bound states, A¹Σ_u⁺(0_u⁺) and b³Π_u(0_u⁺), have been studied by experiment andcalculations. It is shown that these two states are fullycoupled by spin-orbit interaction, characterised by itsintermediate strength. The intermediate character of thedynamics is established by complicated wavepacket oscillationatterns and a value of 75 cm^-1is estimated for the coupling strength at thestate crossing.</p><p>The experiments on the Li₂molecule are performed by coherent control ofrovibrational molecular wavepackets. First, the Deutsch-Jozsaalgorithm is experimentally demonstrated for three-qubitfunctions using a pure coherent superposition of Li₂rovibrational eigenstates. The function’scharacter, either constant or balanced, is evaluated by firstimprinting the function, using a phase-tailored femtosecond(fs) pulse, on a coherent superposition of the molecularstates, and then projecting the superposition onto an ionicfinal state using a second fs pulse at a specific delay time.Furthermore, an amplitude-tailored fs pulse is used to exciteselected rovibrational eigenstates and collision induceddephasing of the wavepacket signal, due to Li₂-Ar collisions, is studied experimentally. Theintensities of quantum beats decaying with the delay time aremeasured under various pressures and the collisional crosssections are calculated for each well-defined rovibrationalquantum beat, which set the upper limitsfor ure dephasingcross sections.</p><p><b>Keywords:</b>Ultrafast laser spectroscopy, pump-probetechnique, predissociation, wavepacket, pin-orbit interaction,coherent control, (pure) dephasing</p>

An algorithm for extracting event information from a Coulomb Explosion Imaging (CEI) position sensitive detector (PSD) is developed and compared with previously employed schemes. The PSD is calibrated using a newly designed grid overlay and validates the quality of the described algorithm. Precision calculations are performed to determine how best the CEI apparatus at The University of Waterloo can be improved. An algorithm for optimizing coincidence measurements of polyatomic molecules in CEI experiments is developed. Predictions of improved efficiency based on this algorithm are performed and compared with experiments using a triatomic molecule. Analysis of an OCS targeted CEI experiment using highly charged Argon ions to initiate ionization is performed. The resulting measurements are presented using a variety of visualization tools to reveal asynchronous and sequential fragmentation channels of OCS3+.

Doctor of Philosophy / Department of Physics / Artem Rudenko / Carlos Trallero-Herrero / Ultrafast laser systems (pulse durations 10-100 femtoseconds) allow for the practical production of intense fields (≥ 10¹⁴ W/cm²) in a table-top, laboratory setup. The development of this technology has opened the door to studying the interaction of intense laser fields with atoms, molecules, and solid media. These experiments revealed a wealth of dynamics and interplay between the field, ion, and the freed electron, which has led to the production of first attosecond pulses and opened the field of attosecond science. The dynamics of the electron in an intense laser field are fundamental to strong- field phenomena such as higher-order harmonic generation, high energy above threshold ionization, and non-sequential double ionization. As the electron can be strongly accelerated by the instantaneous field, the dynamics depend on both the field's amplitude and wavelength. The latter dependence comes from the fact that the period of the field increases with wavelength. Thus, the electron is accelerated for a longer time and the energy gained is proportional to the wavelength squared. Recent evidence supports the claim that the electron- field interaction at longer wavelengths must include the contribution of the magnetic field and/or the radiation pressure of the field, adding to the wealth of effects associated with strong- field interactions. This thesis explores several routes towards fulfilling gaps in our understanding of the wavelength-scaling of strong- field interactions. I first demonstrate several important developments that reduce the complexity of generating non-sinusoidal, light transient waveforms in the near-infrared, opening the ability to tailor waveforms for more control on strong- field interactions. Next, I demonstrate the development of a strong- field, femtosecond source at wavelengths from 5 micrometers to 9 micrometers. To date, this is the first few-cycle, strong- field (≥ 10¹⁴ W/cm²) source in the long-wave infrared. An important advantage to this design is the wavelength tunability, which provides a control knob for understanding strong- field interactions across a broad wavelength range. Afterwards, I present applications of wavelength tunable sources in strong- field absorption in semiconductors. Specifically, I measure the absorbance of a strong laser field in gallium arsenide as a function of laser polarization, which varies the density of states available to the electron. This is performed for four laser wavelengths spanning 1.2 micrometers to 2.4 micrometers. With these absorbance measurements, we can compare the dependence of the photoexcitation rate on several parameters and compare it to theory. We find that the change in absorbance with density of states deviates from theoretical predictions as the photon order for the photoexcitation increases from two to three. This could be attributed to the field modifying the energy-momentum relationship of the conduction band. To conclude the thesis, I present simulations on a recent experimentally demonstrated technique for amplifying few-cycle electric fields. Due to the difficulty in making these sources, the model I developed includes many of the parameters involved in designing the system. This simulation can be used to plan design criteria, such as nonlinear crystal thickness, for peak performance of the amplification process.

Doctor of Philosophy / Department of Physics / Zenghu Chang / It is still a dream to image the dynamics of electrons in atoms and molecules experimentally. This is due to the fact that such motion takes place in an ultra-short time scale; for example, an electron moves around the Bohr orbit in about 150-as (1 as = 10 -18 s), and pulses much shorter than this limit are not currently available to probe such fast dynamics. In recent years, an isolated single attosecond pulse has been produced by extracting the cutoff of harmonic spectrum driven by a laser pulse as short as ~ 5fs (1fs =10-15 s). But, these pulses are still too long in order to make the dream come true. Here, we study the possibility of generation of a much shorter and wavelength tunable single attosecond pulse by using polarization gating. In the experiment, we compressed ~30fs pulses from the laser amplifier down to ~6fs and characterized them. These linearly polarized pulses were converted to ellipticity varying pulses, and by exploiting the property of the strong dependence of the harmonic signal with the ellipticity of the laser, an XUV supercontinuum was produced in the harmonic spectrum which could support 60-as pulses. The bandwidth of such a supercontinuum, and therefore the duration of the attosecond pulses, is limited mainly by the currently available energy of the driving laser pulses at few cycle limits. In this project, we present an approach which allowed us to scale up the energy of such pulses by a factor of 1.5 in “Hollow Core Fiber / Chirped Mirrors Compressor”. Finally, in order to temporarily characterize the attosecond pulses we designed and built an “Attosecond Streak Camera”. Most of such cameras to date are limited to measuring a 1 dimensional energy spectrum and have only a few degrees of acceptance angle. Our camera is capable of measuring 2d momentum of the photoelectrons with large acceptance angle, for example ~ 65o at the photoelectron of energy ~15 eV. Recently, we observed the sidebands in addition to the main peaks in their laser assisted XUV photoelectron spectrum. The single attosecond pulses, after being characterized with this high speed camera, can be used to explore the dynamics of electrons at the attosecond scale.