Wendell T. Hill

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We have created a long-lived (≈40 s) persistent current in a toroidal Bose-Einstein condensate held in an all-optical trap. A repulsive optical barrier across one side of the torus creates a tunable weak link in the condensate circuit, which can affect the current around the loop. Superflow stops abruptly at a barrier strength such that the local flow(More)
Distributed feedback dye lasers, which use a holographic grating, present a very simple and reliable way to generate ultrashort pulses. We have developed a new technique for wavelength tuning of this type of laser by projecting the image of a second grating into the dye cell. Single-line operating and tuning was demonstrated with transform-limited output(More)
A laser beam with phase singularities is an interesting object to study in optics and may have important applications in guiding atoms and molecules. We explore the characteristics of a singularity in a nondiffracting Bessel beam experimentally by use of a programmable spatial light modulator with 64-level phase holograms. The diffraction efficiency with(More)
We present two spatial-shaping approaches - phase and amplitude - for creating two-dimensional optical dipole potentials for ultracold neutral atoms. When combined with an attractive or repulsive Gaussian sheet formed by an astigmatically focused beam, atoms are trapped in three dimensions resulting in planar confinement with an arbitrary network of(More)
This thesis investigates polarization-insensitive methods for optical signal processing. Two signal processing techniques are studied: clock recovery based on two-photon absorption in silicon and demultiplexing based on cross-phase modulation in highly nonlinear fiber. The clock recovery system is tested at an 80 Gb/s data rate for both back-to-back and(More)
We report for the first time the ability to perform time resolved imaging of terahertz (THz) waves propagating within a Fabry-Perot resonator on a LiNbO<sub>3</sub> slab. Electro-optic effect is used to record the full spatiotemporal evolution of THz fields inside the resonator. In addition to revealing the real-space behavior, the data further demonstrate(More)
The energy spectrum of relativistic electrons is an important characterization of high intensity laser-matter interactions. We present a technique that utilizes Cerenkov radiation to measure the time-resolved energy distribution of electrons. Electrons escaping from targets irradiated by high-intensity laser pulses were measured, demonstrating the(More)
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