Sandia National Laboratories

About: Sandia National Laboratories is a facility organization based out in Livermore, California, United States. It is known for research contribution in the topics: Laser & Thin film. The organization has 21501 authors who have published 46724 publications receiving 1484388 citations. The organization is also known as: SNL & Sandia National Labs.

A three-dimensional neural recording microsystem with implantable data compression circuitry

Abstract: A 256-site, fully implantable, 3-D neural recording microsystem has been developed. The microsystem incorporates four active neural probes with integrated circuitry for site selection, amplification, and multiplexing. The probes drive an embedded data-compression ASIC that successfully detects neural spikes in the presence of neural and circuit noise. The spike detection ASIC achieves a factor of 12 bandwidth reduction while preserving the key features of the action potential waveshape necessary for spike discrimination. This work extends the total number of neural channels that can be recorded across a transcutaneous inductively coupled wireless link from 25 to 312. When a spike is detected, this ASIC serially shifts the 5-bit amplitude and 5-bit address of the spike off of the chip over a single 2.5 Mb/s wired or wireless line. The spike detection ASIC occupies 6 mm/sup 2/ in 0.5 /spl mu/m features and consumes 2.6 mW while the entire microsystem consumes 5.4 mW of power from a 3-V supply.

Photoinduced hysteresis changes and optical storage in (Pb,La)(Zr,Ti)O3 thin films and ceramics

Abstract: Pb(Zr,Ti)O3 and (Pb,La)(Zr,Ti)O3 thin films and bulk ceramics are shown to exhibit two distinct, but related types of photoinduced changes in their hysteresis behavior: (1) a photoinduced suppression of the switchable polarization and (2) a photoinduced voltage shift. Both effects give rise to stable and reproducible hysteresis changes and, thus, either could be the basis of an optical memory. Both phenomena can be explained by trapping of photogenerated charge at domain boundaries to minimize internal depolarizing fields. The space‐charge field that causes the voltage‐shift effect is primarily due to the migration and subsequent trapping of electrons. However, the thickness dependence of the voltage shift implies that the trapped charge is not confined to the interface. The voltage‐shift kinetics exhibit a stretched‐exponential dependence, whereas the polarization‐suppression effect follows an exponential time dependence. However, both effects exhibit similar relaxation times. In addition, the relaxation...

Broken Symmetry Dielectric Resonators for High Quality Factor Fano Metasurfaces

Abstract: We present a new approach to dielectric metasurface design that relies on a single resonator per unit cell and produces robust, high quality factor Fano resonances. Our approach utilizes symmetry breaking of highly symmetric resonator geometries, such as cubes, to induce couplings between the otherwise orthogonal resonator modes. In particular, we design perturbations that couple “bright” dipole modes to “dark” dipole modes whose radiative decay is suppressed by local field effects in the array. Our approach is widely scalable from the near-infrared to radio frequencies. We first unravel the Fano resonance behavior through numerical simulations of a germanium resonator-based metasurface that achieves a quality factor of ∼1300 at ∼10.8 μm. Then, we present two experimental demonstrations operating in the near-infrared (∼1 μm): a silicon-based implementation that achieves a quality factor of ∼350; and a gallium arsenide-based structure that achieves a quality factor of ∼600, the highest near-infrared qualit...

Best Possible Inequalities for the Probability of a Logical Function of Events

Abstract: (1965). Best Possible Inequalities for the Probability of a Logical Function of Events. The American Mathematical Monthly: Vol. 72, No. 4, pp. 343-359.