Sandia Corporation

National Technology & Engineering Solutions of Sandia, LLC

City University of New York

University of Texas System

Mayo Foundation for Medical Education and Research

Boston University

U.S. Department of Energy

The Trustees of Boston College

Eric A Shaner

Xiaoyu Miao

Brandon Passmore

Igal Brener

Michael C Wanke

Daniel M Wasserman

Thomas John Rogers

Todd Andrew Barrick

Gregory Aizin

Lorenzo Jiron

Gregory Conrad Dyer

Paul Davids

Xin Zhang

Anna Tauke-Pedretti

John F Klem

David W Peters

Richard Douglas Averitt

Jin K Kim

Hu Tao

Bradley C Salzbrenner

Mark Lee

Michael Goldflam

Troy Daniel Ribaudo

Willie John Padilla

Andrew Strikwerda

S James Allen

Edward G Winrow

Zachary Medaris Wilson

Young Chul Jun

Katherine Anne Barrick

Victor H Chavez

Devyani Lal

Benjamin Varberg Olson

Mark B Wehde

Michael Alexis Omana

Clark N Kadlec

Torben Ray Fortune

Dora K Wiemann

John M Angeli

Emil Andrew Kadlec

John L Reno

Kevin Fortier

Todd A Barrick

A reusable, protective face mask has two detachable filter trays that attach on each side of the mask, a soft elastomeric face seal, and straps to go around the user's head. Exhalations and inhalations can pass through the same filter material. The filter trays can accept arbitrary filter media. A forward-facing port can be used to increase speech intelligibility by transmitting sound through a diaphragm without a prohibitive amount of distortion. Manufacture of the mask is facilitated because the mask body and the other mask components can be produced by injection molding. Decontamination and sterilization are facilitated because the mask can be fully disassembled.

Reusable filtering face mask

A test fixture facilitates non-destructive testing of a protective mask. The test fixture includes a mock facial structure, a clamping form that makes a seal around at least part of the facial structure, and can employ the retaining straps of the protective mask to a make a seal around at least part of the facial structure. In use, the protective mask is tested in situ on the facial structure. In some examples, the clamping form has a negative contour of the mock facial structure or of the outer surface of a protective mask that is to be tested. The testing can include repetitive testing of the fit, structural components (e.g., ultrasonic welds and straps), and the degradation of materials as a function of donning/doffing or environmental factors (e.g., temperature and humidity).

Respirator test system

Systems and methods are provided for filtering coherent infrared light from a thermal background for protection of infrared (IR) imaging arrays and detection systems. A Michelson interferometer is used for coherent light filtering. In an implementation, a system includes a fixed mirror, a beam splitter, and a moving mirror which can be controlled translationally, as well as tip/tilt. The Michelson interferometer may be used as an imaging system. For imaging applications, a system may comprise a tunable array of micro-electromechanical systems (MEMS) mirrors. A mid-wave IR interferometer with electronic feedback and MEMS mirror array is provided.

Tunable coherent light filter for optical sensing and imaging

A time-resolved microwave reflectance apparatus comprises a pulsed or modulated optical source that irradiates a semiconductor sample with an excitation pump beam, a microwave oscillator that irradiates the sample with a continuous beam of microwaves, and a microwave detector that detects the microwaves reflected by the sample. Therefore, charge detection, rather than conventional absorption measurements (that detect the loss of photons), can be used to extract the absorption coefficient and band edge of a semiconductor material.

Apparatus and method to measure semiconductor optical absorption using microwave charge sensing

In a superlattice (SL) photodetector, each period of the SL includes first and second semiconductor layers having different compositions, at least one of which comprises indium arsenide (InAs). At least one of these two semiconductor layers has a graded composition. In embodiments, the first semiconductor layer comprises InAs and the second semiconductor layer is a graded layer comprising indium arsenide antimonide (InAsSb), wherein the antimony (Sb) concentration is varied. In examples, the Sb concentration in the second layer gradually increases from the top and bottom toward the middle of the layer.

Superlattice photodetector having improved carrier mobility

A mid-infrared tunable metamaterial comprises an array of resonators on a semiconductor substrate having a large dependence of dielectric function on carrier concentration and a semiconductor plasma resonance that lies below the operating range, such as indium antimonide. Voltage biasing of the substrate generates a resonance shift in the metamaterial response that is tunable over a broad operating range. The mid-infrared tunable metamaterials have the potential to become the building blocks of chip based active optical devices in mid-infrared ranges, which can be used for many applications, such as thermal imaging, remote sensing, and environmental monitoring.

Mid-infrared tunable metamaterials

An electrically tunable terahertz two-path plasmonic interferometer with an integrated detection element can down convert a terahertz field to a rectified DC signal. The integrated detector utilizes a resonant plasmonic homodyne mixing mechanism that measures the component of the plasma waves in-phase with an excitation field that functions as the local oscillator in the mixer. The plasmonic interferometer comprises two independently tuned electrical paths. The plasmonic interferometer enables a spectrometer-on-a-chip where the tuning of electrical path length plays an analogous role to that of physical path length in macroscopic Fourier transform interferometers.

Two-path plasmonic interferometer with integrated detector

A tunable plasmonic crystal comprises several periods in a two-dimensional electron or hole gas plasmonic medium that is both extremely subwavelength (&#x2dc;&#x3bb;/100) and tunable through the application of voltages to metal electrodes. Tuning of the plasmonic crystal band edges can be realized in materials such as semiconductors and graphene to actively control the plasmonic crystal dispersion in the terahertz and infrared spectral regions. The tunable plasmonic crystal provides a useful degree of freedom for applications in slow light devices, voltage-tunable waveguides, filters, ultra-sensitive direct and heterodyne THz detectors, and THz oscillators.

Tunable plasmonic crystal

A highly directional thermal emitter device comprises a two-dimensional periodic array of heavily doped semiconductor structures on a surface of a substrate. The array provides a highly directional thermal emission at a peak wavelength between 3 and 15 microns when the array is heated. For example, highly doped silicon (HDSi) with a plasma frequency in the mid-wave infrared was used to fabricate nearly perfect absorbing two-dimensional gratings structures that function as highly directional thermal radiators. The absorption and emission characteristics of the HDSi devices possessed a high degree of angular dependence for infrared absorption in the 10-12 micron range, while maintaining high reflectivity of solar radiation (&#x2dc;64%) at large incidence angles.

Highly directional thermal emitter

A heterodyne photomixer spectrometer comprises a receiver photomixer that is driven at a different frequency than the source photomixer, thereby maintaining the coherent nature of the detection, eliminating etalon effects, and providing not only the amplitude but also the phase of the received signal. The heterodyne technique can be applied where the source and receiver elements are components of a waveguide thereby forming an on-chip heterodyne spectrometer.

Heterodyne photomixer spectrometer with receiver photomixer driven at different frequency than source photomixer

An apparatus and method are disclosed for detecting terahertz radiation at room temperature. A detecting pixel includes a sub-wavelength split-ring resonator, and is mechanically coupled to (but thermally decoupled from) a substrate via a cantilever formed from two materials that have a significant mismatch in their thermal expansion coefficients. Incident radiation causes the split-ring resonator to resonate, thereby generating heat that is transferred to the cantilever, causing the cantilever to flex. An optical readout system includes a secondary light source, such as a laser, that shines on a reflective surface on the pixel, whereby a photodiode detects the reflected light and permits calculation of a relative deflection of the pixel in the nanometer range. An exemplary detector has a noise equivalent power rating of approximately 60 pW/&#x221a;Hz.

Thermal imager using metamaterials

A tunable extraordinary optical transmission (EOT) device wherein the tunability derives from controlled variation of the dielectric constant of a semiconducting material (semiconductor) in evanescent-field contact with a metallic array of sub-wavelength apertures. The surface plasmon resonance wavelength can be changed by changing the dielectric constant of the dielectric material. In embodiments of this invention, the dielectric material is a semiconducting material. The dielectric constant of the semiconducting material in the metal/semiconductor interfacial region is controllably adjusted by adjusting one or more of the semiconductor plasma frequency, the concentration and effective mass of free carriers, and the background high-frequency dielectric constant in the interfacial region. Thermal heating and/or voltage-gated carrier-concentration changes may be used to variably adjust the value of the semiconductor dielectric constant.

Tunable surface plasmon devices

A direct detector for terahertz radiation comprises a grating-gated field-effect transistor with one or more quantum wells that provide a two-dimensional electron gas in the channel region. The grating gate can be a split-grating gate having at least one finger that can be individually biased. Biasing an individual finger of the split-grating gate to near pinch-off greatly increases the detector's resonant response magnitude over prior QW FET detectors while maintaining frequency selectivity. The split-grating-gated QW FET shows a tunable resonant plasmon response to FIR radiation that makes possible an electrically sweepable spectrometer-on-a-chip with no moving mechanical optical parts. Further, the narrow spectral response and signal-to-noise are adequate for use of the split-grating-gated QW FET in a passive, multispectral terahertz imaging system. The detector can be operated in a photoconductive or a photovoltaic mode. Other embodiments include uniform front and back gates to independently vary the carrier densities in the channel region, a thinned substrate to increase bolometric responsivity, and a resistive shunt to connect the fingers of the grating gate in parallel and provide a uniform gate-channel voltage along the length of the channel to increase the responsivity and improve the spectral resolution.

Direct detector for terahertz radiation

Growing community of inventors

Rio Rancho, NM, United States of America

Eric A Shaner