Electrically tunable plasmonic metasurface as a matrix of nanoantennas.

We report the fabrication and characterization of a plasmonic metasurface comprising electrically-contacted sub-wavelength gold dipole nanoantennas, conformally coated by a thin hafnia film, an indium tin oxide layer and a backside mirror, forming metal-oxide-semiconductor (MOS) capacitors, for use as an electrically-tunable reflectarray or metasurface. By voltage biasing the nanoantennas through metallic connectors and leveraging the carrier refraction effect in the MOS capacitors, our measurements demonstrate phase control in reflection over a range of about 30°, with a constant magnitude of reflection coefficient of 0.5, and the absence of secondary lobes.

High-resolution SiN spectrometer: architecture & virtual channel synthesis and experimental demonstration.

Up-to-date network telemetry is the key enabler for resource optimization by capacity scaling, fault recovery, and network reconfiguration among other means. Reliable optical performance monitoring in general and, specifically, the monitoring of the spectral profile of WDM signals in fixed- and flex- grid architectures across the entire C-band, remains challenging. This article describes a two-stage spectrometer architecture amenable to integration on a single chip that can measure quantitatively the spectrum across the entire C-band with a resolution of ∼ 1.

Inpatient Neurology Deaths and Factors Associated With Discharge to Hospice.

Background And Purpose: The Neurology Mortality Review Committee at our institution identified variability in location of death for patients on our inpatient neurology services. Hospice may increase the number of patients dying in their preferred locations. This study aimed to characterize patients who die on inpatient neurology services and explore barriers to discharge to hospice.

Outcomes of a Neurohospitalist Program at an Academic Medical Center.

Background And Purpose: The purpose is to determine the impact of an academic neurohospitalist service on clinical outcomes.

Methods: We performed a retrospective, quasi-experimental study of patients discharged from the general neurology service before (August 2010-July 2014) and after implementation of a full-time neurohospitalist service (August 2016-July 2018) compared to a control group of stroke patients. Primary outcomes were length of stay and 30-day readmission.

Quality Improvement Metrics and Methods for Neurohospitalists.

Measurement of clinical performance is largely driven by the requirements of the Centers for Medicare and Medicaid Services and accrediting bodies like The Joint Commission. Performance measures include length of stay, readmission rate, mortality rate, hospital-acquired complications, and stroke core measures. Hospital rankings also depend heavily on quality and patient safety indicators.

On the performance of optical phased array technology for beam steering: effect of pixel limitations.

Optical phased arrays are of strong interest for beam steering in telecom and LIDAR applications. A phased array ideally requires that the field produced by each element in the array (a pixel) is fully controllable in phase and amplitude (ideally constant). This is needed to realize a phase gradient along a direction in the array, and thus beam steering in that direction.

A Standardized Checklist Improves the Transfer of Stroke Patients from the Neurocritical Care Unit to Hospital Ward.

Background And Purpose: The transfer of patients with ischemic stroke from the intensive care unit (ICU) to noncritical care inpatient wards involves detailed information sharing between care teams. Our local transfer process was not standardized, leading to potential patient risk. We developed and evaluated an "ICU Transfer Checklist" to standardize communication between the neurocritical care team and the stroke ward team.

Neuroimaging selection for thrombectomy in pediatric stroke: a single-center experience.

Background: The extended time window for endovascular therapy in adult stroke represents an opportunity for stroke treatment in children for whom diagnosis may be delayed. However, selection criteria for pediatric thrombectomy has not been defined.

Methods: We performed a retrospective cohort study of patients aged <18 years presenting within 24 hours of acute large vessel occlusion.

U-shaped PN junctions for efficient silicon Mach-Zehnder and microring modulators in the O-band: erratum.

We correct two minor errors in the manuscript. The effective diameter of the ring modulator should be 62.5 μm rather than 65 μm.

Tri-layer silicon nitride-on-silicon photonic platform for ultra-low-loss crossings and interlayer transitions.

We present a three-layer silicon nitride on silicon platform for constructing very large photonic integrated circuits. Efficient interlayer transitions are enabled by the close spacing between adjacent layers, while ultra-low-loss crossings are enabled by the large spacing between the topmost and bottommost layers. We demonstrate interlayer taper transitions with losses < 0.

High-performance silicon photonic tri-state switch based on balanced nested Mach-Zehnder interferometer.

This work proposes a novel silicon photonic tri-state (cross/bar/blocking) switch, featuring high-speed switching, broadband operation, and crosstalk-free performance. The switch is designed based on a 2 × 2 balanced nested Mach-Zehnder interferometer structure with carrier injection phase tuning. As compared to silicon photonic dual-state (cross/bar) switches based on Mach-Zehnder interferometers with carrier injection phase tuning, the proposed switch not only has better performance in cross/bar switching but also provides an extra blocking state.

U-shaped PN junctions for efficient silicon Mach-Zehnder and microring modulators in the O-band.

We demonstrate U-shaped silicon PN junctions for energy efficient Mach-Zehnder modulators and ring modulators in the O-band. This type of junction has an improved modulation efficiency compared to existing PN junction geometries, has low losses, and supports high-speed operation. The U-shaped junctions were fabricated in an 8" silicon photonics platform, and they were incorporated in travelling-wave Mach-Zehnder modulators and microring modulators.

Design and implementation of a modulator-based free-space optical backplane for multiprocessor applications.

Design and implementation of a free-space optical backplane for multiprocessor applications is presented. The system is designed to interconnect four multiprocessor nodes that communicate by using multiplexed 32-bit packets. Each multiprocessor node is electrically connected to an optoelectronic VLSI chip which implements the hyperplane interconnection architecture.

Implementation of a compact, four-stage, scalable optical interconnect for photonic backplane applications.

We report on the implementation of a dense 512-beam free-space optical interconnect linking four optoelectronic VLSI chips at the backplane level. The system presented maximizes the positioning tolerances of the components by use of slow f-number (f/16) Gaussian beams and oversized apertures. A beam-clustering scheme whereby a 4 x 4 array of beams is transmitted by each minilens is used to provide a high channel density.