A5105350481- Terahertz technology and applications
- Metamaterials and Metasurfaces Applications
- Laser-Matter Interactions and Applications
- Advanced Fiber Laser Technologies
- Plasmonic and Surface Plasmon Research
- Physics of Superconductivity and Magnetism
- Photonic and Optical Devices
- Photonic Crystal and Fiber Optics
- Semiconductor Quantum Structures and Devices
- Laser-Plasma Interactions and Diagnostics
- Advanced Antenna and Metasurface Technologies
- Millimeter-Wave Propagation and Modeling
- Laser Design and Applications
- Spectroscopy and Laser Applications
- Antenna Design and Analysis
- Magnetic and transport properties of perovskites and related materials
- Superconducting and THz Device Technology
- Optical Network Technologies
- Rare-earth and actinide compounds
- Multiferroics and related materials
- Topological Materials and Phenomena
- Advanced Condensed Matter Physics
- Iron-based superconductors research
- Mechanical and Optical Resonators
- Laser-induced spectroscopy and plasma
Center for Integrated Nanotechnologies
2014-2024
Los Alamos National Laboratory
2014-2024
Los Alamos Medical Center
1996-2020
Physical Sciences (United States)
2019-2020
National Yang Ming Chiao Tung University
2018
University at Buffalo, State University of New York
2018
Konkuk University
2018
Peac Institute of Multiscale Sciences
2017
Rutgers, The State University of New Jersey
2012-2015
University of Nebraska–Lincoln
2015
Polarization is one of the basic properties electromagnetic waves conveying valuable information in signal transmission and sensitive measurements. Conventional methods for advanced polarization control impose demanding requirements on material attain only limited performance. Here, we demonstrate ultrathin, broadband, highly efficient metamaterial-based terahertz converters that are capable rotating a linear state into its orthogonal one. Based these results create metamaterial structures...
Utilizing terahertz time domain spectroscopy, we have characterized the electromagnetic response of a planar array split ring resonators (SRRs) fabricated upon high resistivity GaAs substrate. The measured frequency dependent magnetic and electric resonances are in excellent agreement with theory simulation. For two polarizations, SRRs yield negative (epsilon < 0). We demonstrate, for first time, dynamical control electrical through photoexcitation free carriers An excited carrier density...
A transient photocurrent model is developed to explain coherent terahertz emission from air irradiated by a symmetry-broken laser field composed of the fundamental and its second harmonic pulses. When total asymmetric across individual optical cycles, nonvanishing electron current surge can arise during ionization air, emitting electromagnetic pulse. Terahertz power scalability also investigated, with pump energy tens millijoules per pulse, peak strengths in excess 150 kV/cm are routinely produced.
We demonstrate THz metamaterials exhibiting either amplitude control, via carrier injection or depletion in the active semiconductor substrate frequency photoexcitation of carriers into semiconducting materials incorporated sub-wavelength metamaterial structure.
The limiting effects of varying the thickness a dielectric overlayer on planar double split-ring resonator (SRR) arrays are studied by terahertz time-domain spectroscopy. Uniform overlayers from 100 nm to 16 mum thick deposited onto fixed SRR in order shift resonance frequency electric response. We discuss bounds shifting and emphasize resulting limitations for SRR-based sensing. These results presented context typical biosensing situations compared previous work other existing sensing platforms.
We present a class of artificial materials that exhibit tailored response to the electrical component electromagnetic radiation. These electric metamaterials are investigated theoretically, computationally, and experimentally using terahertz time-domain spectroscopy. structures display resonant including regions negative permittivity ${ϵ}_{1}(\ensuremath{\omega})<0$ ranging from...
We present a novel approach of antireflection coating using metamaterials. It dramatically reduces the reflection and greatly enhances transmission near specifically designed frequency over wide range incidence angles for both transverse magnetic electric polarizations. A classical interference mechanism is identified through analytical derivations numerical simulations. elucidates that tailored magnitude phase waves reflected transmitted at boundaries metamaterial are responsible antireflection.
Planar electric split ring resonator (eSRR) metamaterials and their corresponding inverse structures are designed characterized computationally experimentally utilizing finite element modeling THz time domain spectroscopy. A complementary response is observed in transmission. Specifically, for the eSRRs a decrease transmission at resonance whereas display an increase The frequency dependent effective complex dielectric functions extracted from experimental data and, combination with...
We design and implement a multipixel spatial modulator for terahertz beams using active metamaterials. Our first-generation device consists of 4×4 pixel array, where each is an array subwavelength-sized split-ring resonator elements fabricated on semiconductor substrate, independently controlled by applying external voltage. Through transmission experiments, we show that the has uniform modulation depth around 40% across all pixels, negligible crosstalk, at resonant frequency. This can...
Abstract We demonstrate a broadband, polarization independent, wide-angle absorber based on metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of solar spectrum exhibits low absorptivity (emissivity) at mid- far-infrared wavelengths. The complex unit cell consists eight pairs gold nano-resonators that are separated from ground plane by thin silicon dioxide spacer. Our experimental measurements reveal high-performance...
We experimentally demonstrate a planar terahertz Fano metamaterial with an ultrahigh quality (Q) factor of 227. This is achieved by the excitation nonradiative dark modes introducing tiny asymmetry in structure. The extremely sharp quadrupole and resonances are excited at normal incidence for orthogonal polarizations electric field. In order to capture narrow linewidth resonance modes, we perform high resolution time-domain measurements scan length 200 picoseconds frequency 5 GHz. These...
During the past decades, major advances have been made in both generation and detection of infrared light; however, its efficient wavefront manipulation information processing still encounter great challenges. Efficient fast optoelectronic modulators spatial light are required for mid-infrared imaging, sensing, security screening, communication navigation, to name a few. However, their development remains elusive, prevailing methods reported so far suffered from drawbacks that significantly...
We present the design, numerical simulations and experimental measurements of terahertz metamaterial absorbers with a broad flat absorption top over wide incidence angle range for either transverse electric or magnetic polarization depending on incident direction. The absorber unit cell consists two sets structures resonating at different but close frequencies. overall spectrum is superposition individual components becomes significant bandwidth. results are in excellent agreement simulations.
In this Letter we present resonance properties in terahertz metamaterials consisting of a split-ring resonator array made from high temperature superconducting films. By varying the temperature, observed efficient metamaterial switching and frequency tuning with some features not revealed before. The results were well reproduced by numerical simulations using experimentally measured complex conductivity film. We developed theoretical model that explains features, which takes into account...
We demonstrated giant optical activity using a chiral metamaterial composed of an array conjugated bilayer metal structures. The metamaterials were further integrated with photoactive inclusions to accomplish wide tuning range the through illumination near-infrared light. strong chirality observed in our results negative refractive index, which can also be well controlled by excitation.
Solar energy promises a viable solution to meet the ever-increasing power demand by providing clean, renewable alternative fossil fuels. For solar thermophotovoltaics (STPV), high-temperature absorbers and emitters with strong spectral selectivity are imperative efficiently couple radiation into photovoltaic cells. Here, we demonstrate refractory metasurfaces for STPV tailored absorptance emittance characterized in-situ measurements, featuring thermal stability up at least 1200 C. Our...
Abstract Controlled charge flows are fundamental to many areas of science and technology, serving as carriers energy information, probes material properties dynamics 1 a means revealing 2,3 or even inducing 4,5 broken symmetries. Emerging methods for light-based current control 5–16 offer particularly promising routes beyond the speed adaptability limitations conventional voltage-driven systems. However, optical generation manipulation currents at nanometre spatial scales remains basic...