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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Plasmon-phonon coupling between mid-infrared chiral metasurfaces and molecular vibrations

Plasmon-phonon coupling between metamaterials and molecular vibrations provides a new path for studying mid-infrared light-matter interactions and molecular detection. So far, the coupling between the plasmonic resonances of metamaterials and the phonon vibrational modes of molecules has been realized under linearly polarized light. Here, mid-infrared chiral plasmonic metasurfaces with high circular dichroism (CD) in absorption over 0.65 in the frequency range of 50 to 60 THz are demonstrated to strongly interact with the phonon vibrational resonance of polymethyl methacrylate (PMMA) molecules at 52 THz, under both left-handed and right-handed circularly polarized (LCP and RCP) light. The mode splitting features in the absorption spectra of the coupled metasurface-PMMA systems under both circular polarizations are studied in PMMA layers with different thicknesses. The relation between the mode splitting gap and the PMMA thickness is also revealed. The demonstrated results can be applied in areas of chiral molecular sensing, thermal emission, and thermal energy harvesting.

42 ENGINEERING↗
DOE OSTI2017

Tunability of indium tin oxide materials for mid-infrared plasmonics applications

Transparent conductive oxides (TCOs) have emerged as alternative plasmonic materials in recent years to replace noble metals. The advantages of TCOs include CMOS compatibility, tunability of optical and structural properties, and reduced losses. In this work, we demonstrate how post-deposition annealing of indium tin oxide (ITO) films in oxygen atmosphere allows for tuning their optical dispersion properties to the mid-infrared spectral range while simultaneously reducing their absorption losses. In particular, we show a materials strategy that extends the epsilon-near-zero (ENZ) point of ITO from the near-infrared to the mid-infrared range. This is demonstrated by fabricating periodic arrays of ITO discs of varying diameters and characterizing their plasmonic resonances in the mid-infrared range from λ = 5 to 10 µm. The developed ITO plasmonic structures pave the way to the development of novel infrared active devices for sensing and spectroscopy on a silicon-compatible platform.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Ultrafast quantum photonics enabled by coupling plasmonic nanocavities to strongly radiative antennas

Quantum emitters coupled to plasmonic nanostructures can act as exceptionally bright sources of single photons, operating at room temperature. Plasmonic mode volumes supported by these nanostructures can be several orders of magnitude smaller than the cubic wavelength, which leads to dramatically enhanced light–matter interactions and drastically increased photon production rates. However, when increasing the light localization further, these deeply subwavelength modes may in turn hinder the fast outcoupling of photons into free space. Plasmonic hybrid nanostructures combining a highly confined cavity mode and a larger antenna mode circumvent this issue. We establish the fundamental limits for quantum emission enhancement in such systems and find that the best performance is achieved when the cavity and antenna modes differ significantly in size. We experimentally support this idea by photomodifying a nanopatch antenna deterministically assembled around a nanodiamond known to contain a single nitrogen–vacancy (NV) center. As a result, the cavity mode shrinks, further shortening the NV fluorescence lifetime and increasing the single-photon brightness. Our analytical and numerical simulation results provide intuitive insight into the operation of these emitter–cavity–antenna systems and show that this approach could lead to single-photon sources with emission rates up to hundreds of THz and efficiencies close to unity.

47 OTHER INSTRUMENTATION↗
DOE OSTI2026

Electrically tunable nonlinear light generation in plasmonic tunnel junctions

Active and efficient control of nonlinear optical processes is essential for integrated photonics, with applications in signal processing, ultrafast switching, and quantum light manipulation. While nanophotonic structures are powerful for enhancing nonlinearities, achieving wide-range electrical tunability has remained a challenge. Plasmonic tunnel junctions offer a unique path to bridge this gap because they combine extreme optical field confinement with direct electrical control in a single nanoscale device. Here, we report the first, to our knowledge, demonstration of electrically tunable second-harmonic generation (SHG) in plasmonic tunnel junctions. Using ultra-stable epitaxial heterostructures, we achieve reproducible modulation of SHG with depths up to ∼500% and magnitudes above 1.3V −1 . We identify two mechanisms, electric-field-induced SHG (EFISH) and ion migration, that can either compete or cooperate depending on junction thickness and bias, enabling both broad tunability and ferroelectric-like hysteretic switching. These findings establish plasmonic tunnel junctions as a platform for electrically controlled nonlinear optics, with potential for nanoscale light sources, reconfigurable modulators, and neuromorphic photonic devices..

42 ENGINEERING↗
DOE OSTI2016

Time Resolved Optical Studies on The Plasmonic Field Enhancement of Bacteriorhodopsin Proton Photo-current: Final Technical Report Covering Aug 31, 2015–Aug 31, 2016

Our research continues to focus on the effects of plasmonic nanoparticles on organic and inorganic light-harvesting materials. Recent work has focused on the synthesis of stabilized gold nanoparticles to enhance the efficiency of dye-sensitized solar cells (DSSCs). Two major concerns in dye sensitized solar cells (DSSCs) are efficient light absorption and charge collection. Charge collection typically suffers because transport of electrons through the mesoporous TiO 2 substrate is slow. Thus, one obvious way to improve charge collection is to reduce the thickness of the TiO 2 . Alternatively, a form of TiO 2 with fewer grain boundaries, such as nanotubes, could be used in place of sintered nanospheres. Unfortunately, both of these solutions end up reducing the amount of surface area available to adsorb dye molecules. This directly reduces the percentage of photons absorbed. This problem could be avoided if dye molecules with larger absorption were designed; although synthetic chemists seem to be pushing the limits of what is achievable. Plasmonic nanoparticles offer an alternative way to boost light absorption. It is well known that plasmonic nanoparticles can enhance the local electric field of resonant frequencies of light. If this were in the same spectral region as the dye’s absorption band it would increase the percentage of absorbed photons. One concern is that if the nanoparticles are too close to the dye molecules they can quench the excited state. To avoid this problem, we prepared gold nanoparticles with a silica shell. This limited the amount of quenching while still permitting some enhancement of absorption. Unfortunately, we ran into some serious issues. The iodide based electrolyte etched the gold nanoparticles, completely dissolving them within a few hours. The silica shell should have provided protection but there were pinholes through which iodide could diffuse. Increasing the thickness of the silica to over 10 nm prevented etching but also limited any photon absorption enhancement.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Modeling and Fabrication of IR Photonic Devices for Plasmon-Mediated Catalysis and Sensor Applications

Sandia National Laboratories (SNL) and Southwest Research Institute (SWRI) collaborated on this CRADA to explore novel 3-D metamaterial structures or devices that are proficient at eliciting surface plasmon-polaritons at infrared (IR) frequencies. The derived structures play a central role in answering fundamental questions pertaining to the vibrational coupling of molecules with surface plasmons and the potential binding interactions or catalytic effects that result from this coupling. Three-D metamaterial samples fabricated at SNL were characterized by SWRI, showing potential utility for binding molecules with similar vibrational frequencies that match the plasmon-polaritons of the metamaterial structure.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Emerging Materials for Plasmonics, Metamaterials and Metasurfaces

This symposium addressed emerging topics of hybrid nanophotonics including plasmonics, metamaterials, metasurfaces, and two-dimensional materials to overcome existing limitations that prevent the development of practical photonic devices. Symposium topics are related to fundamental, basic, and applied research, and the symposium addressed the need for basic and applied research in developing plasmonic materials and metamaterials aiming at fast optical switching including utilizing materials with large broadband optical nonlinearities, the ability to effectively reduce transmission, and ultra-fast response time. The advanced material designs are put forth by numerical and experimental methods with an emphasis on developing hierarchical designs and two/three-dimensional self-assembly of multifunctional materials and advance material concepts including transformational optics. Novel plasmonic materials for optoelectronics with the aim to increase in the data rate are of great interest. Besides that, the efforts are in understanding electromagnetic phenomena in solid-state materials and structure involving the latest developments in semiconductor materials and device physics. In the fundamental research and engineering science, the symposium topics in electronics and material science focus on investigations of novel metamaterial, metasurface and optical component designs as well as diving into developments of alternative materials. The symposium provided a general overview of recent advances in new design concepts and material platforms, including fabrication techniques and promising applications enabled by the new developments.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Nanoscale Imaging of Optical-Frequency Plasmonic Energy Transfer in Individual Nanoparticles and their Assemblies

The nonradiative transfer of energy from plasmonic metal nanostructures to their neighboring environments is a rapidly expanding research area because of its tremendous potential impact on photovoltaics and photocatalysis. Despite the significant progress achieved via optical spectroscopies, understanding the differing and competing energy transfer pathways available to these systems still presents a major challenge due to a lack of insight into their nanoscale optical responses. With the atom-scale spatial resolving power of the electron microscope and its ability to probe optical transitions, electron spectroscopies like EELS are uniquely suited for these challenges. Our proposal addressed STEM/EELS techniques (Camden) to directly measure and even control energy transfer pathways in hybrid plasmon-resonator systems and leveraged detailed theoretical models combined with simulation (Masiello) to understand the essential underlying physics. In particular, the outcome of our proposed studies deepened the fundamental understanding of how surface plasmons shed energy to their environment and the practical knowledge gained here will influence the design of future high-efficiency solar energy-harvesting devices and photocatalysts capable of operating throughout the visible and the infrared.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2024

The International Conference on Surface Plasmon Photonics 10

The International Conference on Surface Plasmon Photonics (SPP Conference) is widely regarded as the premier global conference in nanoscale photonics. The SPP10 meeting was held in the United States for the first time, at Rice University in Houston, Texas, on May 21-26, 2023. This conference was an outstanding venue for communicating research breakthroughs and accomplishments in the represented fields, as well as for visibility, networking, and recruiting, for students, postdoctoral fellows, and faculty throughout the US and the world as they attended this conference. The SPP10 conference hosted sessions on fundamental science, innovations, and applications in modern photonics with high potential for commercialization. Plenary sessions, invited talks from leading scientists in the field, and contributed talks from the larger photonics community on highly multidisciplinary topics of Quantum Plasmonics and Photonics; Energy Harvesting and Plasmonic Chemistry; Active Photonics and Devices; Ultrafast and Nonlinear Phenomena; and Machine Learning/Artificial Intelligence. The meeting schedule includes 3 plenary speakers, 31 Invited talks and 58 contributed talks. There were three well attended poster sessions which included lively discussions. Lunch time in the University Colleges allowed unstructured time for additional networking and discussions. The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both U.S. and foreign scientists, senior researchers, young investigators, and students. The co-chairs of the conference were Prof. Naomi Halas and Prof. Peter Nordlander. The grant from DoE supported student’s and early career scientist’s registration and housing on campus.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
NASA NTRS1983

Long-range surface plasmons in electrode structures

Surface polaritons guided by symmetric double metal film structures are analyzed, with particular attention given to the attenuation of the two long-range modes that occur. It is found that long-range surface plasmon polariton modes do exist for double electrode structures over a limited range of material parameters. Guided by thin metal electrodes, surface plasmon polaritons can achieve millimeter plus propagation distances in the near infrared. It is pointed out that if the slab is electrooptic, then very low voltages will be needed to manipulate the waves. The fact that long-range modes exist simultaneously with junction tunnel plasmons may be of use in providing directional radiation from light-emitting junctions or the inverse process of light to electrical energy conversion.

Stegeman, G. I.↗
NASA NTRS1983

Harnessing surface plasmons for solar energy conversion

NASA research on the feasibility of solar-energy conversion using surface plasmons is reviewed, with a focus on inelastic-tunnel-diode techniques for power extraction. The need for more efficient solar converters for planned space missions is indicated, and it is shown that a device with 50-percent efficiency could cost up to 40 times as much per sq cm as current Si cells and still be competitive. The parallel-processing approach using broadband carriers and tunable diodes is explained, and the physics of surface plasmons on metal surfaces is outlined. Technical problems being addressed include phase-matching sunlight to surface plasmons, minimizing ohmic losses and reradiation in energy transport, coupling into the tunnels by mode conversion, and gaining an understanding of the tunnel-diode energy-conversion process. Diagrams illustrating the design concepts are provided.

Anderson, L. M.↗
NASA NTRS1986

Observation of radiative surface plasmons in metal-oxide-metal tunnel junctions

A peak in the UV region of the spectrum of light emitted from metal-oxide-metal (MOM) tunnel junctions has been observed at room temperature. Both the amplitude and wavelength of the peak are sensitive to applied junction bias. The UV peak corresponds to the normal or radiative surface plasmon mode while a visible peak, also present in the present spectra and reported in past MOM literature, is due to the tangential or nonradiative mode. The radiative mode requires no surface roughness or gratings for photon coupling. The results show that it is possible to obtain radiative surface plasmon production followed by a direct decay into photons with MOM tunnel diodes. A MOM diode with a double anode structure is found to emit light associated only with the nonradiative mode. The thickness dependence of the UV peak, along with the experimental results of the double anode MOM diode and the ratio of the UV peak to visible peak, support the contention that the UV light emission is indeed due to the radiative surface plasmon.

Donohue, J. F.↗
NASA NTRS1986

Lateral shift of an optical beam due to leaky surface-plasmon excitations

A leaky-wave theory is applied to the study of the lateral shift of a bounded optical beam reflected from a prism-air-metal (and prism-metal-air) layered configuration with surface-plasmon excitations. The locations of the pole and the zero of the reflection coefficient for the leaky surface-plasmon mode are calculated as one varies the thickness of the center layer. The excited surface-plasmon mode is leaky because of the presence of the prism. Both the real part and the imaginary part of the pole are affected by the energy leakage. The detailed structure of the reflected intensity and the forward and backward shifts of the reflected beam are illustrated.

Chuang, S. L.↗
NASA NTRS1997

Annealing Effects on the Surface Plasmon of MgO Implanted with Gold

Gold ion implantation was carried out with the energy of 1.1 MeV into (100) oriented MgO single crystal. Implanted doses are 1, 3, 6, 10 x 10(exp 16) ions/sq cm. The gold irradiation results in the formation of gold ion implanted layer with a thickness of 0.2 microns and defect formation. In order to form gold colloids from the as-implanted samples, we annealed the gold implanted MgO samples in three kinds of atmospheres: (1)Ar only, (2)H2 and Ar, and (3)O2 and Ar. The annealing over 1200 C enhanced the gold colloid formation which shows surface plasmon resonance band of gold. The surface plasmon bands of samples annealed in three kinds of atmospheres were found to be at 535 nm (Ar only), 524 nm(H2+Ar), and 560 nm (02+Ar), The band positions of surface plasmon can be reversibly changed by an additional annealing.

Ueda, A.↗
NASA NTRS2001

Devices based on surface plasmon interference filters

Devices based on surface plasmon filters having at least one metal-dielectric interface to support surface plasmon waves. A multi-layer-coupled surface plasmon notch filter is provided to have more than two symmetric metal-dielectric interfaces coupled with one another to produce a transmission spectral window with desired spectral profile and bandwidth. Such notch filters can form various color filtering devices for color flat panel displays.

Wang, Yu↗
NASA NTRS2010

Nanorice Particles: Hybrid Plasmonic Nanostructures

A new hybrid nanoparticle, i.e., a nanorice particle, which combines the intense local fields of nanorods with the highly tunable plasmon resonances of nanoshells, is described herein. This geometry possesses far greater structural tunability than previous nanoparticle geometries, along with much larger local field enhancements and far greater sensitivity as a surface plasmon resonance (SPR) nanosensor than presently known dielectric-conductive material nanostructures. In an embodiment, a nanoparticle comprises a prolate spheroid-shaped core having a first aspect ratio. The nanoparticle also comprises at least one conductive shell surrounding said prolate spheroid-shaped core. The nanoparticle has a surface plasmon resonance sensitivity of at least 600 nm RIU(sup.-1). Methods of making the disclosed nanorice particles are also described herein.

Wang, Hui↗
DOE OSTI2014

Plasmon resonant cavities in vertical nanowire arrays

Tunable plasmon resonant cavity arrays in paired parallel nanowire waveguides are presented. Resonances can be observed when the waveguide length is an odd multiple of quarter plasmon wavelengths, consistent with boundary conditions of node and antinode at the ends. Two nanowire waveguides can satisfy the dispersion relation of a planar metal-dielectric-metal waveguide of equivalent width equal to the square field average weighted gap. Confinement factors of over 10.sup.3 are possible due to plasmon focusing in the inter-wire space.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2020

Plasmonic energy conversion device for vapor generation

The present invention is related to using a plasmonic energy conversion device comprised of a non-permeable substrate and of a plurality of nanorods, either free standing or embedded in aluminum matrix, that utilizes plasmons to generate vapor from a fluid as a result of being exposed to radiation. Methods of manufacturing the plasmonic energy converter device are described.

14 SOLAR ENERGY↗