James S. Harris - US grants

A vertical field-effect transistor may in principal combine the advantages of both the permeable base transistor and hetrojunction biploar transistor in providing the capability of achieving ballistic action. A device design is developed as a new structure for studying ballistic transport, and modifications to the structure are aimed at limiting parasitics; the results are explored to make practical use of the device possible.

0423076
Smith
The goal of this project is the design of a novel implantable brain imaging device called an IOS sensor. Based on a microscale integrated array of intermingled GaAs NIR emitters and detectors, this device will be optimized to image the intrinsic optical signal (IOS), a diffuse optical reflectance correlate of brain electrical activity rich in detail about sensory and motor information processing in mammalian cortex. The neurobiological utility of IOS imaging is already very well established, but all previous IOS imaging has used bulky, benchtop-scale instruments that require subjects to be immobilized and, almost always, anesthetized. Because of its small size, the IOS sensor will allow unprecedented imaging of cortical activity patterns in unanaesthetized and freely behaving subjects. Applications of the implantable IOS sensor will include neuroscience research, prosthetics for neurological injury patients, and drug discovery.

This award supports Stanford?s ongoing program on advanced gravitational wave detectors. The research will focus on continuing projects on the development and testing of the Advanced LIGO seismic isolation and control systems and on the investigation of improved sensors for increasing performance of active isolation systems. In addition, research will continue on the use of ultraviolet light to mitigate the buildup of electrostatic charges on Advanced LIGO mirrors and on the evaluation of thermalized optical losses in core optic materials and optical coatings. All these efforts have as their goal the increased performance of Advanced LIGO.

Gravitational waves were predicted almost 90 years ago in Einstein's General Theory of Relativity, but they have not yet been detected due to the extreme sensitivity required. Interacting black holes, coalescing compact binary stellar systems, stellar collapses, pulsars and low mass X-ray binaries are all possible sources of gravitational waves, as is the random background of radiation from the early universe. Laser interferometer detectors, which operate by measuring strains in the fabric of space-time that are expected to be produced by gravitational waves, are now becoming operational and may soon give us a first detection. Detectors of higher performance, such as Advanced LIGO, should allow us to develop gravitational wave astronomy as a new window on the Universe. Stanford has a strong, multidisciplinary program in developing the technology for such detectors with participants from many areas of physics and engineering. The program provides training for future scientists and engineers at both the undergraduate and graduate levels, it integrates basic scientific research with scientific education, and includes outreach programs that inform and educate the broader community.

0967257
Schnitzer

The applicants plan to create mode-locked, ultrashort-pulsed lasers that are made in a monolithic manner on a single semiconductor wafer using photonic crystal technology. In the long run, the resulting lasers could reshape how life scientists, educators and students use nonlinear optical microscopy. For researchers, large-scale or distributed two-photon imaging systems could provide wholly new capabilities for inspecting the biological world or screening large libraries of specimens by the combined use of many microscopes in parallel. The lasers will also find immediate usage in their own neuroscience research, for visualizing neuronal dynamics in awake behaving mice. In combination with microfabricated scanning mirrors, the chip-scale lasers will allow us to make tiny two-photon microscopes such that each mouse carries its own microscope on its cranium The research will be a collaboration between two Stanford labs of complementary expertise. James Harris is a pioneer in the use of molecular beam epitaxy (MBE) techniques for growing semiconductor optical devices. Mark Schnitzer is deeply experienced in the design and construction of two-photon microscopes and their usages for brain imaging. As a proof-of-principle demonstration, the two groups will design, build, test, and refine 10 tiny two-photon microscopes based on chip-scale lasers.