Optical Storage, Atom Traps Featured at Annual Laser Science Meeting
A special plenary session on Monday afternoon featured a keynote address by Carl Wieman (University of Colorado) on new studies in Bose-Einstein condensation, preceded by a ceremonial session marking the presentation of the 1997 Schawlow Prize to Erich Ippen (MIT) and Charles Shank (Lawrence Berkeley Laboratory). The conference also featured four critical review presentations, a feature first introduced in 1995 to highlight exciting new developments in laser science by recognized experts. This year, the four speakers and their topics included Wolfgang Ketterle (MIT) on Bose-Einstein condensation and the atom laser; Nasser Peyghambarian (University of Arizona) on polymer optoelectronics; Daniel Chemla (Lawrence Berkeley National Laboratory) on recent advances in single molecule spectroscopy; and Katherine Hall (MIT) on the progress and outlook for all-topical ultrafast switching.
Charles Brucker of Eastman Kodak gave a Monday morning tutorial on optical storage materials, reviewing the design, fabrication and performance issues for the deposited thin film layer stacks used in current and potential future generation optical disk storage media. According to Glenn Sincerbox of the University of Arizona, who reported on recent advances in the enabling technologies and materials for holographic data storage, "Holographic storage technology has the potential of providing high capacity, rapid access and fast retrieval of digitally stored information."
In a later tutorial on Monday, Donald Carlin of Sarnoff Corp. summarized several developing optical storage technologies: near-field optical storage; electron-trapping optical memories; two-photon memories; and persistent hole burning. According to Carlin, some of the remaining technical challenges include development of improved storage materials, improved diode lasers, and compact optical systems. In addition, "New technologies must be aimed at consumer products to be pervasive," he said. "An emerging technology must be embraced by a number of major manufacturers worldwide in order to have the hope of being accepted as a standard." The new storage products must also bring overwhelming advantages to users as magnetic storage devices continue to improve.
Atom Traps and Cold Collisions
Using spectroscopy of weakly bound, excited molecules formed by collisions of ultra-cold atoms in an optical field to yield their ground-state atomic scattering properties, new Nobelist William Phillips of NIST reported in a Tuesday morning session on the observance of unambiguous evidence of the effect of radiative retardation on the molecular spectra. Other NIST researchers have developed a new technique for observing collisions at very low relative velocities, which was used to measure rates of spin-polarized Penning ionizing collisions for both fermionic and bosonic isotopes of xenon. The same group has found that the collision rate of atoms arranged in an optical lattice is suppressed by at least a factor of two when it has thermalized, in comparison to atoms in the free state.
Several speakers reported on the status of various schemes for quantum computation. A research group at Los Alamos National Laboratory is investigating two proposed quantum computer technologies: nuclear magnetic resonance, in which nuclear spins are used to store quantum information, and trapped ions, in which quantum information is stored in the atomic quantum levels. They recently demonstrated quantum computation with cold, trapped calcium ions. Scientists with the Weapons Science Directorate are investigating the use of electron-nuclear double resonance with laser-pulse induced selection electronic excitation control for quantum computing applications.
In addition, researchers at the California Institute of Technology are developing a scheme by which quantum networks might be realized. According to Hideo Mabuchi, these networks would consist of spatially separated quantum nodes connected by quantum channels. The nodes would generate, process and store quantum information, and consist of the internal states of a collection of atoms. The channels would transport quantum states and distribute entanglement by way of photons.
Hyperpolarized Noble Gas MRI
Researchers at the University of Michigan have used laser optical pumping techniques to enhance the polarization of noble gas isotopes, including helium-3 and xenon-129, for magnetic resonance imaging (MRI). According to Timothy Chupp, although helium-3 is particularly suitable for lung and air space imaging, xenon-129 is of interest because xenon gas crosses the blood-gas barrier, is dissolved in the blood, and is carried to tissue where magnetization can build up and be imaged. Using this approach, scientists at the Universitat Mainz in Germany performed the first clinical survey of he-3 MRI of the lungs of healthy probands, as well as patients suffering from various lung diseases.
Photorefractive Keratectomy and Retinal Physiology
Researchers at Summit Technology, Inc. have developed a next- generation large area excimer laser refractive workstation which uses a unique, patented, single-use laser disc to treat myopia, hyperopia, and both myopic and hyperopic compound astigmatism. The Emphasis LaserDisc contains all the required information that is necessary to impart the desired corneal surface shape transformations to achieve the intended refractive outcome. In a related area, Donald Hood of Columbia University described new techniques that allow the study of single classes of cell, such as rod or cone receptors, and rod onbipolars. Also, a relatively new multi-stimulation technique allows for simultaneous recording from many localized regions. Hood illustrated his techniques with studies of light adaptation of the normal retina, as well as with studies of the abnormal activity of diseased retinas.
Optics in Entertainment
Through advances in plasma tube and optical coating technologies, laser manufacturers have met the ever-increasing demands of the entertainment industry with improved output power, color balance, and packaging of white ion lasers. According to Kurt Klavuhn of Spectra-Physics Lasers, who spoke at a Monday morning session, these advancements provide more flexibility and versatility for further advancing the cutting edge of laser entertainment displays. For example, Robert Martinsen of the Corporation for Laser Optics Research described a new projection display, called Color Visiona. The display uses pulsed, solid state lasers with a modulation technique known as acousto-optic line writing to create images exhibiting a unique combination of brightness, spatial resolution, and chromatic strength, specifically suited for large area displays in bright ambient lighting.
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