Semiconductor Hyperbolic Metamaterials at the Quantum Limit
Abstract not provided.
Publications
Towards Electromagnetic Simulations to Translate an Exterior Environment to Assess Effects on Electronic System Performance
This report explores the coupling between EIGER simulations and a transmission line analytical model to enable end-to-end simulations to translate an exterior electromagnetic environment to assess effects on electronic system performance.
Epsilon-near-zero materials: Optical properties and applications
Abstract not provided.
Compact Silicon Photonic Phase Modulators based on Epsilon-Near_Zero Materials
Abstract not provided.
Preliminary Survey on the Effectiveness of an Electromagnetic Dampener to Improve System Shielding Effectiveness
This report explores the potential for reducing the fields and the quality factor within a system cavity by introducing microwave absorbing materials. Although the concept of introducing absorbing (lossy) materials within a cavity to drive the interior field levels down is well known, increasing the loading into a complex weapon cavity specifically for improved electromagnetic performance has not, in general, been considered, and this will be the subject of this work. We compare full-wave simulations to experimental results, demonstrating the applicability of the proposed method.
Low Dissipation Spectral Filtering at Long Infrared Wavelengths using a Field-Effect Tunable III-V Hybrid Metasurface
Abstract not provided.
Improved quantitative circuit model of realistic patch-based nanoantenna-enabled detectors
Journal of the Optical Society of America B: Optical Physics
Improving the sensitivity of infrared detectors is an essential step for future applications, including satellite- and terrestrial-based systems. We investigate nanoantenna-enabled detectors (NEDs) in the infrared, where the nanoantenna arrays play a fundamental role in enhancing the level of absorption within the active material of a photodetector. The design and optimization of nanoantenna-enabled detectors via full-wave simulations is a challenging task given the large parameter space to be explored. Here, we present a fast and accurate fully analytic circuit model of patch-based NEDs. This model allows for the inclusion of real metals, realistic patch thicknesses, non-absorbing spacer layers, the active detector layer, and absorption due to higher-order evanescent modes of the metallic array. We apply the circuit model to the design of NED devices based on Type II superlattice absorbers, and show that we can achieve absorption of ∼70% of the incoming energy in subwavelength (∼λ∕5) absorber layers. The accuracy of the circuit model is verified against full-wave simulations, establishing this model as an efficient design tool to quickly and accurately optimize NED structures.
Compact epsilon-near-zero silicon photonic phase modulators
Optics Express
In this paper, we analyze a compact silicon photonic phase modulator at 1.55 μm using epsilon-near-zero transparent conducting oxide (TCO) films. The operating principle of the non-resonant phase modulator is field-effect carrier density modulation in a thin TCO film deposited on top of a passive silicon waveguide with a CMOS-compatible fabrication process. We compare phase modulator performance using both indium oxide (In2O3) and cadmium oxide (CdO) TCO materials. Our findings show that practical phase modulation can be achieved only when using high-mobility (i.e. low-loss) epsilon-near-zero materials such as CdO. The CdO-based phase modulator has a figure of merit of 17.1°/dB in a compact 5 μm length. This figure of merit can be increased further through the proper selection of high-mobility TCOs, opening a path for device miniaturization and increased phase shifts.
Low dissipation spectral filtering using a field-effect tunable III-V hybrid metasurface
Applied Physics Letters
Considering the power constrained scaling of silicon complementary metal-oxide-semiconductor technology, the use of high mobility III-V compound semiconductors such as In0.53Ga0.47As in conjunction with high-κ dielectrics is becoming a promising option for future n-type metal-oxide-semiconductor field-effect-transistors. Development of low dissipation field-effect tunable III-V based photonic devices integrated with high-κ dielectrics is therefore very appealing from a technological perspective. In this work, we present an experimental realization of a monolithically integrable, field-effect-tunable, III-V hybrid metasurface operating at long-wave-infrared spectral bands. Our device relies on strong light-matter coupling between epsilon-near-zero (ENZ) modes of an ultra-thin In0.53Ga0.47As layer and the dipole resonances of a complementary plasmonic metasurface. The tuning mechanism of our device is based on field-effect modulation, where we modulate the coupling between the ENZ mode and the metasurface by modifying the carrier density in the ENZ layer using an external bias voltage. Modulating the bias voltage between ±2 V, we deplete and accumulate carriers in the ENZ layer, which result in spectrally tuning the eigenfrequency of the upper polariton branch at 13 μm by 480 nm and modulating the reflectance by 15%, all with leakage current densities less than 1 μA/cm2. Our wavelength scalable approach demonstrates the possibility of designing on-chip voltage-tunable filters compatible with III-V based focal plane arrays at mid- and long-wave-infrared wavelengths.
ATLOG Modeling of Buried Cables from the November 2016 HERMES Electromagnetic Pulse Experiments
This report compares ATLOG modeling results for the response of a finite-length dissipative buried conductor interacting with a conducting ground to a measurement taken November 2016 at the High-Energy Radiation Megavolt Electron Source (HERMES) facility. We use the ATLOG frequency-domain method based on transmission line theory. Estimates of the impedance per unit length and admittance per unit length for a cable laying in a PVC pipe embedded in a concrete block are reported. Current wave shapes from both a single conductor and composite differential mode and antenna mode arrangements are close to those observed in the experiments. Intentionally Left Blank
Resonant Ultrathin Infrared Detectors Enabling High Quantum Efficiency
Abstract not provided.
Formulas For Plane Wave Coupling To A Transmission Line Above Ground With Terminating Loads
This report considers plane wave coupling to a transmission line consisting of a wire above a conducting ground. Comparisons are made for the two types of available source models, along with a discussion about the decomposition of the line currents. Simple circuit models are constructed for the terminating impedances at the ends of the line including radiation effects. Results from the transmission line with these loads show good agreement with full wave simulations. Intentionally Left Blank
Voltage Tuning of Reflectance from a Strongly Coupled Metasurface-Semiconductor Hybrid Structure
Abstract not provided.
Reflectance Modulation from a Metasurface Coupled to Intersubband Transitions in Semiconductor Quantum Wells using Quantum Tunneling
Abstract not provided.
Modeling E1/E2 EMP events on Power Grids
Abstract not provided.
Electromagnetic Dampeners to Improve Shielding Effectiveness
Abstract not provided.
Ultrafast Epsilon-Near-Zero Electroabsorption Modulators
Abstract not provided.
Parametric Analysis of Vertically Oriented Metamaterials for Wideband Omnidirectional Absorption
Abstract not provided.
Electromagnetic Dampeners to Improve Shielding Effectiveness
Abstract not provided.
Decay length
Abstract not provided.
First principles model of electric and magnetic cable braid penetrations
2018 International Applied Computational Electromagnetics Society Symposium in Denver, ACES-Denver 2018
In this paper, we report our recent findings about a first principles, multipole-based model of electric and magnetic cable braid penetrations. We consider for brevity a one-dimensional array of wires, but the model can be readily applied to realistic cable geometries. Comparisons between the first principles method and analytical formulas will be provided for both electric and magnetic penetration cases. These comparisons confirm that our first principles model works within the geometric characteristics of many commercial cables.
Massively parallel frequency domain electromagnetic simulation codes
2018 International Applied Computational Electromagnetics Society Symposium in Denver, ACES-Denver 2018
This paper provides an overview of the electromagnetic frequency domain simulation capabilities of the Electromagnetic Theory department at Sandia National Laboratories via a description of two of its codes. EIGER is a Method of Moments code for electromagnetic simulations, but it only runs on traditional CPUs, not on new architectures. Gemma is in development to replace EIGER and will run on many architectures, including CPUs, GPUs, and MICs, by leveraging the Kokkos library.
Vertically oriented metamaterial broadband linear polariser
Electronics Letters
Control and manipulation of polarisation is an important topic for imaging and light matter interactions. In the infrared regime, the large wavelengths make wire grid polarisers (WGPs) a viable option, as it is possible to create periodic arrays of metallic wires at that scale. The recent advent of metamaterials has spurred an increase in non-traditional polariser motifs centred around more complicated repeat units, which potentially provide more functionality. The authors explore the use of 2D arrays of single and back-to-back vertically oriented cross dipoles arranged in a cubic in-plane silicon matrix. They show that both single and back-to-back versions have higher rejection ratios and larger bandwidths than either WGPs or 2D arrays of linear dipoles.
A hybrid tunable III-V metasurface using voltage-controlled quantum tunneling
Abstract not provided.
Ultrathin energy-efficient field-effect tunable III-V hybrid metasurface
Abstract not provided.
Results 51–75 of 194