Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session F62: Nanostructures and Metamaterials IV |
Hide Abstracts |
Sponsoring Units: DMP Chair: Igal Brener, Sandia National Laboratories Room: Mile High Ballroom 4C |
Tuesday, March 3, 2020 8:00AM - 8:12AM |
F62.00001: Engineering quantum light emission from color-centers in atomically thin crystals with phase gradient metasurfaces. Pankaj Jha, Ghazaleh Kafaie Shirmanesh, Hamidreza Akbari, Meir Grajower, Benjamin Vest, Harry Atwater Single-photon sources are elementary building blocks for photonic quantum technologies. However, progress in photonic quantum technologies has been constrained due to a lack of suitable materials with desired optical properties and the challenges in achieving coherent light-matter interaction at the quantum level. Here, we report a new approach for building chip-scale quantum hardware with color-centers in wide bandgap materials, such as hexagonal boron nitride (hBN), interfaced with planar arrays of classical nanoantennas, also known as metasurfaces. We investigated both exfoliated and chemical vapor grown hBN samples at room temperature. We performed photon-photon correlation measurements to isolate centers with single-photon emission characteristics and designed a phase gradient metasurface such that the emission from these color-centers can be efficiently extracted as well as redirected along a preferred direction. Our approach of interfacing these bright emitters with photonic metasurfaces and manipulating their emission characteristics would enable new opportunities for on-chip quantum photonics. |
Tuesday, March 3, 2020 8:12AM - 8:24AM |
F62.00002: Modeling NV charge stability in nanodiamonds with DFT Claire Meara, Patrick Briddon, Mark Rayson, Jonathan Goss The nitrogen-vacancy (NV) defect in diamond is a controllable quantum system with strong fluorescence. When placed in nanodiamonds it provides nanoscale magnetometry and single biological cell tracking[1]. NV must be stable and negatively charged close to the nanodiamond surface. However, NV charge-state fluctuations near surfaces result in intermittent fluorescence; this effect is highly correlated with surface type and structures[2]. Electron affinity has been posited as a cause, but contradictions exist and underlying mechanisms still need to be fully understood. Recent work shows NV charge alternates with pH[3], suggesting acceptor levels from surface radicals play a role. Using DFT the electronic structure of NVs in nanodiamonds is studied for different, commonly observed terminations, adsorbates and surface radicals. A measure of charge stability is defined and an underlying cause for observed charge instability for certain terminations is proposed. Routes to manipulating NV surfaces to provide stable NV- in nanodiamonds is discussed, thereby allowing more reliable spatiotemporal nanosensors. |
Tuesday, March 3, 2020 8:24AM - 8:36AM |
F62.00003: Epsilon-near-zero modes in transdimensional planar plasmonic nanostructures Igor Bondarev, Hamze Mousavi, Vladimir Shalaev Transdimensional (TD) materials are ultrathin planar nanostructures composed of a precisely controlled finite number of monolayers[1]. Plasmonic TD materials offer advances such as controlled light confinement and thickness-controlled light-matter coupling that can further develop the fields of nanophotonics and metamaterials. We use quantum electrodynamics and the confinement-induced nonlocal dielectric response model based on the Keldysh-Rytova electron interaction potential to study the epsilon-near-zero modes (ENZ) of plasmonic films in the TD regime[2]. New remarkable effects are revealed. They are the plasmon mode degeneracy lifting and the dipole emitter coupling to the ENZ modes split. The latter leads to the thickness-controlled spontaneous decay with up to three-orders-of-magnitude increased rates. Knowledge of these features is advantageous both for the fundamental understanding of the electromagnetic properties and for the development of the new design principles of efficient photonic nanodevices with desired characteristics that are built on ultrathin metallic TD films. -- [1]A.Boltasseva & V.M.Shalaev, ACS Photonics 6, 1 (2019); [2]I.V.Bondarev, H.Mousavi, & V.M.Shalaev, arXiv1908.00640. |
Tuesday, March 3, 2020 8:36AM - 8:48AM |
F62.00004: Plasmon Assisted Coherent Random Lasing Dipendra S Khatri, Jiyang Chen, Ying Li, Elyahb Allie Kwizera, Xiaohua Huang, Christos Argyropoulos, Thang Hoang Random lasing occurs as the result of a coherent optical feedback from multiple scattering centers. Here, we demonstrate that plasmonic gold nanostars, through their small tips, are efficient light scattering centers which assist very narrow bandwidth and highly amplified coherent random lasing at a low lasing threshold. First, by embedding plasmonic gold nanostars in a rhodamine 6G dye gain medium, we observed a series of very narrow random lasing peaks with full-width at half-maximum (FWHM) ~0.8 nm. By contrast, free rhodamine 6G dye exhibited only a single lasing peak with FWHM of 6 nm. The lasing threshold for the dye with gold nanostars was two times smaller than that for a free dye. Further, by coating the tip of a single-mode fiber with these nanostars, we demonstrated the collection of the random lasing signal through the fiber that can easily be guided and analyzed. Time-resolved measurements showed a significant increase in the emission rate at above the lasing threshold, indicating a stimulated emission process. |
Tuesday, March 3, 2020 8:48AM - 9:00AM |
F62.00005: Photoluminescence quantum efficiency of nanowire quantum dots on silicon substrates Jiarong Cui, Yifei Wang, Ho Vinh, Vinh Q Nguyen Nanowire quantum dots grown on silicon substrates provide promising technologies for integrating advanced photonic technologies on a silicon microelectronics. In this research our GaAsP nanowires contain GaAs quantum dot in the middle of the nanowires. We report the photoluminescence quantum efficiency as well as the thermal quenching mechanism of nanowire quantum dots prepared by vapor−liquid−solid method. We have performed high resolution spectroscopy, quantum yield, power dependence, and temperature dependence measurements of photoluminescence intensity from nanowire quantum dots. The data provide a picture of the quantum efficiency, thermal quenching processes and activation energy levels of nanowire quantum dots. The results provide an important step in the realization of nanowire quantum dots for photonic devices on silicon platform. |
Tuesday, March 3, 2020 9:00AM - 9:12AM |
F62.00006: Environmentally friendly core-shell quantum dots for light-emitting devices: A computational study Mariami Rusishvili, Stefan Wippermann, Dmitri Talapin, Giulia Galli Semiconductor quantum dots (QDs) have been successfully used as light emitters in a variety of applications [1]. CdSe QDs exhibit the best performance in terms of tunable colors in the visible range and luminescence quantum yield. However, they contain a toxic heavy metal and the search for environmentally friendly nanostructured semiconductors is an active field of research. Recently InP based QDs have emerged as a promising alternative [2] to CdSe, although they exhibit broader emission spectra, possibly due to the sensitivity of their electronic structure to small morphological changes. Here we report on a first principle computational study of the structural and opto-electronic properties of InP/Zn(S/Se) core shell QDs. We used DFT with semi-local and hybrid functionals and the QuantumEspresso package (https://www.quantum-espresso.org/). We show that composition and interface morphology are key to achieve narrow emission lines, and we discuss the interplay between quantum confinement and strain in determining the electronic properties of these systems. |
Tuesday, March 3, 2020 9:12AM - 9:24AM |
F62.00007: Engineering thermochromic properties with plasmonics, quantum dots, and 2D materials. Dongheon Ha, Evgheni Strelcov, steven Blankenship, Amit Agrawal, Andrei Kolmakov, Nikolai Zhitenev For temperature-sensing applications, it is desirable to obtain strong thermochromic response in visible spectral range. We experimentally evaluate possible enhancements of sensitive thermochromic materials based on vanadium oxide (VOx) by nanophotonic engineering. First, we compare various growth methods, including a deposition and annealing of thin films and an electrochemical growth of single crystals. Second, we perform macro- and microscale temperature-dependent optical measurements of materials with different composition. Then, we demonstrate an enhanced thermochromic behavior by the application of plasmonic and quantum materials. With periodic gold hemispherical structures atop VO2 crystals, the optical contrast at the VO2 phase transition from semiconductor to metal is increased by ≈ 15 % at visible/near-infrared wavelengths. The enhancement is due to the localized surface plasmon resonances of gold particles and can be described within the Maxwell-Garnett effective medium theory. We also discuss other approaches, including the coupling of two dimensional materials and colloidal quantum dots, to further tailor temperature-dependent optical response of thermochromic materials. Finally, we introduce possible applications focusing on nanoscale temperature sensing. |
Tuesday, March 3, 2020 9:24AM - 9:36AM |
F62.00008: Surface functionalization of nanoparticles for fabrication of size-tunable and electrochemically actuable nanostructured shell assembly Mark Bartolo, Ryan Brisbin, Ryan Baxter, Sayantani Ghosh Surface modification of quantum dots (QDs) is one of the most versatile methods of customizing their optical and electronic properties. Our goal is to leverage surface functionalization of CdSe/ZnS QDs for optimal directed assembly to be utilized in biological and biomedical cargo delivery systems. We have developed nano-assembled micro-shell structures composed of gold nanoparticles functionalized with custom-designed ligands1 which allowed plasmonic actuation. Here, we focus on Bis(Imino)Pyradine (BIP) ligands which have improved thermal stability, optical properties, and biocompatibility of the shell structures, while allowing cargo release via electrochemical stimulation. In addition, the versatility of the BIP ligands have made it possible for us to tune the shell diameter from 200 nm to 1 micron, which vastly broadens the field of applications. In this study we present a systematic characterization of the QD surface chemistry to observe and understand correlations between QD diameter, ligand size and shell size. |
Tuesday, March 3, 2020 9:36AM - 9:48AM |
F62.00009: Transition to strong coupling regime for quantum emitters near a plasmonic nanostructures Tigran Shahbazyan We present a model for exciton-plasmon coupling based on energy exchange mechanism between quantum emitters (QE) and localized surface plasmons in metal-dielectric structures. Plasmonic correlations between QEs give rise to a collective state exchanging its energy cooperatively with a resonant plasmon mode. By defining carefully the plasmon mode volume for a QE ensemble, we obtain a relation between the QE-plasmon coupling and the cooperative energy transfer rate that is expressed in terms of local fields. For a single QE near a sharp metal tip, we find analytically the enhancement factor for the QE-plasmon coupling relative to the QE coupling to a cavity mode. For QEs distributed in an extended region enclosing a plasmonic structure, we find that the ensemble QE-plasmon coupling saturates to a universal value independent on system size and shape, consistent with the experiment. |
Tuesday, March 3, 2020 9:48AM - 10:00AM |
F62.00010: Tip-controlled Strong Coupling with Infrared Polaritonic Heterostructures Samuel C. Johnson, Nishant Nookala, Mikhail A. Belkin, Markus B. Raschke Infrared polaritonic metasurfaces based on a multi-quantum-well intersubband transition coupled to a gold antenna heterostructure exhibit record-high nonlinear optical responses and optical power limiting behavior. However, these structures are limited to passive performance depending on fabrication parameters. Here, we use infrared scattering scanning near-field optical microscopy to image single antenna quantum well heterostructures, and to actively tune quantum-well saturation, coupling strength, and quantum path interference through manipulation of the nanocavity mode volume through tip-sample distance control. Further, the AFM tip as a coupled antenna resonator is used to enhance far-field coupling to control photon emission, field orientation, and nanoscopic field heterogeneity. Previous picosecond laser far-field optical power limiting and pump-probe characterization is extended with near-field spectroscopy, using femtosecond laser, picosecond laser, and synchrotron infrared light sources. |
Tuesday, March 3, 2020 10:00AM - 10:12AM |
F62.00011: Active Tuning of Phonons and Surface-Phonon Polariton Resonances Adam Dunkelberger, Chase Ellis, Daniel Ratchford, Alexander Giles, D. Scott Katzer, Andrea Grafton, Vanessa Breslin, Elizabeth Ryland, Mijin Kim, Chul Soo Kim, Igor Vurgaftman, Joseph G Tischler, Jeffrey Owrutsky, Joshua D Caldwell The infrared spectra of many polar semiconductors are dominated by highly reflective reststhralen bands that occur between the transverse and longitudinal optical phonons. Through the LOPC effect, free carriers shift the reststrahlen band to higher frequencies. We have previously shown that photoinjected carriers transiently and reversibly modify the infrared reflectivity of bulk SiC. Within the reststrahlen band, SiC and InP nanostructures can exhibit surface-phonon polariton resonances. Here we report, for the first time, active tuning of SiC and InP surface-phonon polariton resonances via carrier photoinjection, achieving better modulation depths than active tuning in plasmonic systems. In SiC, ultraviolet excitation with femtosecond laser pulses induces >10 cm-1 shifts in the transverse dipole resonance (width = 7 cm-1). Time-resolved infrared reflection spectroscopy reveals that the photoinduced shifts decay in tens of ps, depending on the initial carrier density. Our results suggest that spatial redistribution of photoexcited carriers dominates the time dependence of the active tuning. We also report, for the first time, direct time-resolved infrared spectroscopy of the LO mode of GaN, made experimentally accessible through the Berreman effect. |
Tuesday, March 3, 2020 10:12AM - 10:24AM |
F62.00012: Excitation of non-radiating anapoles in dielectric nanospheres Uttam Manna, John A. Parker, Hiroshi Sugimoto, Brighton Coe, Daniel Eggena, Minoru Fujii, Norbert F. Scherer, Stephen K Gray Nonradiating anapoles are superposition of internal modes that can act as an energy reservoir by reducing the far-field scattering. We report experimental excitation of the electrodynamic anapole mode in isotropic silicon nanospheres at the optical frequencies using radially polarized beam illumination. The superposition of equal and out-of-phase amplitudes of the Cartesian electric and toroidal dipoles produces by a pronounced dip in the scattering spectra with the scattering intensity almost reaching zero – a signature of anapole excitation. The total scattering intensity associated with the anapole excitation is found to be more than 10 times weaker, and the internal energy is found to be 6 times greater for illumination with radially vs. linearly polarized beams. Our approach provides a simple, straightforward alternative path to realize electrodynamic anapole mode at the optical frequencies. |
Tuesday, March 3, 2020 10:24AM - 10:36AM |
F62.00013: Tailoring the chiro-optical response of Si-Ag/Au chiral heterostructure thin films fabricated by glancing angle deposition technique UFUK KILIC, Mathew Hilfiker, Rene Feder, Rafal Korlacki, Eva Schubert, Christos Argyropoulos, Mathias Schubert Chiro-optical response of subwavelength scale nanostructures have been the subject of many research projects such as bio-sensors, topological insulators, and photonic integrated circuit designs. [1] In this study, by using glancing angle deposition technique, subsequent and repeated depositions of silicon(Si) and gold(Au)/silver(Ag) lead to nanometer-dimension sub-chiral segments, and thus, we successfully fabricated spatially coherent, highly porous, super lattice type chiral heterostructure (CHS) thin films. We incorporated the transmission mode Mueller matrix spectroscopic ellipsometry technique with finite element modeling environment in order to investigate the chiro-optical properties of this new type plasmonic metamaterials. Interestingly, Au/Ag sub-chiral segments in CHS result in the emergence of multiple plasmonic modes which can be tunable depending on the Au/Ag-Si ratio in a single turn. Unlike the other studies [2,3] which employs periodic nanostructures made up of single type material, we observed extraordinary optical activity in our fabricated CHS thin films. |
Tuesday, March 3, 2020 10:36AM - 10:48AM |
F62.00014: STM Characterization of hBN-Decoupled Covalent Organic Frameworks Daniel Rizzo, Qingqing Dai, Christopher Bronner, Gregory Veber, Brian J Smith, Michio Matsumoto, Simil Thomas, Giang Duc Nguyen, Patrick R Forrester, William Zhao, Jakob H Jorgensen, William Dichtel, Felix Fischer, Hong Li, Jean-Luc E Bredas, Michael F Crommie Covalent organic frameworks (COFs) are crystalline molecular networks with potential applications in filtration, organic electronics, energy storage, and catalysis. Recent advances in COF synthesis have permitted the growth and characterization of COFs that exhibit different symmetries and that use a wide range of molecular building blocks. Despite this progress, there have only been a limited number of experimental demonstrations of the electronic structure-function relationship for COFs, particularly in the 2D limit. One experimental challenge is how to separate the intrinsic COF electronic structure from the influence of metallic growth substrates. In order to accomplish this, we have introduced an atomic insulating film of hBN between a COF and an underlying metallic substrate to act as a decoupling layer. Using scanning tunneling microscopy and spectroscopy we are able to obtain more detailed spectral information on hBN-decoupled COFs compared to those grown directly on a metallic substrate. First-principles DFT and tight-binding calculations confirm that hBN-decoupled COFs possess spectral features that reflect the COF’s Kagome lattice symmetry. |
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F62.00015: Strain Effect on Silicene Quantum Dot Embedded in Silicane Bi-Ru Wu A new design for silicene quantum dots (SiQDs) embedded in silicane probably makes magnetism and band gap of the SiQD being controllable by hydrogen. In this paper, the strain effect for the embedded SiQD in silicane was investigated by a first-principles method. The homogeneous strain and two types of uniaxial strains are considered. As expected, the band gap can be tuned by strains and the behavior of the band gap are distinct while applied with different strain types. However, the magnetism is still determined by the size and shape of the SiQD. Strain cannot alter the magnetism of the embedded SiQD. The variation of band gap of various shapes of embedded SiQD also have different behaviors under strains. |
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