Two colour pumping was used to investigate the short-pulse technique of Multifrequency Raman Generation (MRG) in the transient regime of Raman scattering. In the course of this study we have demonstrated the ability to generate over thirty Raman orders spanning from the infrared to the ultraviolet, investigated the dependence of this generation on the pump intensities and the dispersion characteristics of the hollow-fibre system in which the experiment was conducted, and developed a simple computer model to help understand the exhibited behaviours. These dependence studies have revealed some characteristics that have been previously mentioned in the literature, such as the competition between MRG and self-phase modulation, but have also demonstrated behaviours that are dramatically different than anything reported on the subject. Furthermore, through a simple modification of the experimental apparatus we have demonstrated the ability to scatter a probe pulse into many Raman orders, generating bandwidth comparable to the best pump-probe experiments of MRG. By using a numeric fast Fourier transform, we predict that our spectra can generate pulses as short as 3. 3fs, with energies an order of magnitude larger than pulses of comparable duration that are made using current techniques.

High-peak power laser systems are defined along with a brief introduction of the technology used in their development and application to the project. A review of concepts surrounding optical pulses, focusing on the particular phenomena involved with the ultrafast, follows. Numerical models involving optical pulses are introduced and verified. An extensive description of the laser system is presented, including models used in its design. Data verifying the correct operation of the laser system is presented and interpreted. A dispersion compensation system, including a function model, is introduced, and its application to the laser system is analyzed. An introduction to pulse characterization techniques is presented followed by the design and verification of two different characterization devices. Experiments utlizing the dispersion compensation system and pulse characterization devices are presented and the results are interpreted. Conclusions are made regarding the performance of the laser system models and pulse characterization devices, along with suggested improvements for each. The results of the experiments are discussed including suggestions for future work.

This thesis describes the design, development, and implementation of a pulsed source of polarization-entangled photons using spontaneous parametric down-conversion in a Sagnac interferometer. A tangle of 0.9286 ± 0.0015, fidelity to the state (|10〉 + |01〉)/√2 of 0.9798 ± 0.0004 and a brightness of 597 pairs/s/mW were demonstrated. Spontaneous parametric down-conversion is a nonlinear optical process in which one photon is split into two lower-frequency photons while conserving momentum and energy, in this experiment nearly degenerate photons are produced. These photons are then interfered at the output beamsplitter of the interferometer, exchanging path entanglement for polarization entanglement and generating the desired polarization-entangled photon pairs.

Methods of controlling molecular rotations using linearly polarized femtosecond and picosecond pulses are considered and analyzed theoretically. These laser pulses, typically in the infrared, are highly non-resonant with respect to the electronic degrees of freedom of the molecules and have intensities of &sim; 10^13 to 10^14 W/cm&sup2;. It is shown how these laser pulses can force small linear molecules to align with the direction of the electric field vector of the laser both in the presence of the laser field as well as after the application of a short laser pulse. Recent experiments on laser-induced molecular alignment are modeled and excellent agreement between experiment and theory is found. Additional methods of controlling molecular rotational dynamics are outlined. The first method considers the forced rotational acceleration of diatomic molecules, called the <i>optical centrifuge</i>. Here, the direction of polarization of a linearly polarized laser field is made to smoothly rotate faster and faster. The molecules, which tend to align with the polarization vector of the laser field, follow the rotation of the laser polarization and are accelerated to high angular momentum. The second method considers the control of field-free rotational dynamics by applying phase shifts to the molecular wave function at select times called <i>fractional revivals</i>. At these select moments, an initially localized wave function splits into several copies of the initial state. Adding phase shifts to the copies then induces interference effects which can be used to control the subsequent evolution of the rotational wave function. This same control scheme has a close link to quantum information and this connection is outlined. Finally, a recently proposed method of controlling the quantum dynamics of the classically chaotic kicked rotor system [J. Gong and P. Brumer, Phys. Rev. Lett. 86, 1741 (2001)] is analyzed from a phase space perspective. It is shown that the proposed quantum control can be linked to small islands of stability in the classical phase space. An experimentally feasible variant of this control scenario using wave packets of molecular alignment is proposed. Two applications of molecular alignment are discussed. The first application uses field-free aligned molecules as a non-linear medium for compression of a laser pulse to the 1 fs regime at optical wavelengths. At such durations, these laser pulses contain nearly a single oscillation of the electric field and represent the shortest laser pulses physically achievable for such frequencies. The second application uses molecular alignment to create a sort of gas phase "molecular crystal" which forms a basis for laser-induced electron diffraction and imaging of the aligned molecules. Here, a first laser pulse aligns the molecules in space. A second laser pulse is then used to ionize outer-shell electrons, accelerate them in the laser field, and steer them back to collide with the parent ion creating a diffraction image with sub-femtosecond and sub-Angstrom resolution.

Two colour pumping was used to investigate the short-pulse technique of Multifrequency Raman Generation (MRG) in the transient regime of Raman scattering. In the course of this study we have demonstrated the ability to generate over thirty Raman orders spanning from the infrared to the ultraviolet, investigated the dependence of this generation on the pump intensities and the dispersion characteristics of the hollow-fibre system in which the experiment was conducted, and developed a simple computer model to help understand the exhibited behaviours. These dependence studies have revealed some characteristics that have been previously mentioned in the literature, such as the competition between MRG and self-phase modulation, but have also demonstrated behaviours that are dramatically different than anything reported on the subject. Furthermore, through a simple modification of the experimental apparatus we have demonstrated the ability to scatter a probe pulse into many Raman orders, generating bandwidth comparable to the best pump-probe experiments of MRG. By using a numeric fast Fourier transform, we predict that our spectra can generate pulses as short as 3. 3fs, with energies an order of magnitude larger than pulses of comparable duration that are made using current techniques.

High-peak power laser systems are defined along with a brief introduction of the technology used in their development and application to the project. A review of concepts surrounding optical pulses, focusing on the particular phenomena involved with the ultrafast, follows. Numerical models involving optical pulses are introduced and verified. An extensive description of the laser system is presented, including models used in its design. Data verifying the correct operation of the laser system is presented and interpreted. A dispersion compensation system, including a function model, is introduced, and its application to the laser system is analyzed. An introduction to pulse characterization techniques is presented followed by the design and verification of two different characterization devices. Experiments utlizing the dispersion compensation system and pulse characterization devices are presented and the results are interpreted. Conclusions are made regarding the performance of the laser system models and pulse characterization devices, along with suggested improvements for each. The results of the experiments are discussed including suggestions for future work.

This thesis describes the design, development, and implementation of a pulsed source of polarization-entangled photons using spontaneous parametric down-conversion in a Sagnac interferometer. A tangle of 0.9286 ± 0.0015, fidelity to the state (|10〉 + |01〉)/√2 of 0.9798 ± 0.0004 and a brightness of 597 pairs/s/mW were demonstrated. Spontaneous parametric down-conversion is a nonlinear optical process in which one photon is split into two lower-frequency photons while conserving momentum and energy, in this experiment nearly degenerate photons are produced. These photons are then interfered at the output beamsplitter of the interferometer, exchanging path entanglement for polarization entanglement and generating the desired polarization-entangled photon pairs.

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)

We have used ultrafast optics, primarily focused on the nonlinear processes of Polarization Gating and of Optical Parametric Amplification, one for measurement and the other for imaging purposes. For measurement, we have demonstrated a robust method of measurement to simultaneously measure both optical pulses used in a pump-probe type configuration. We refer to this method of pulse measurement as Double Blind Polarization Gating FROG. We have demonstrated this single-shot method for measuring two unknown pulses using one device. In addition to pulse measurement, we have demonstrated the processes of Optical Parametric Amplification (OPA) applicability to imaging of complex objects. We have done this where the Fourier transform plane is used during the interaction. We have amplified and wavelength converted a complex image. We observe a gain of ~100, and, although our images were averaged over many shots, we used a single-shot geometry, capable of true single-shot OPA imaging. To our knowledge, this is the first Fourier-plane OPA imaging of more than a single spatial-frequency component of an image. We observe more than 30 distinct spatial frequency components in both our amplified image and our wavelength shifted image. We have demonstrated all-optical spatial filtering for these complex images. We have demonstrated that direct Fourier filtering of spatial features is possible by using a shaped pump beam. We can isolate certain portions of the image simply by rotating the crystal.