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https://www.readbyqxmd.com/read/28526826/high-efficiency-broadband-second-harmonic-generation-in-single-hexagonal-gaas-nanowire
#1
Jing Wang, Ying Yu, Yu-Ming Wei, Shun-Fa Liu, Juntao Li, Zhang-Kai Zhou, Zhi-Chuan Niu, Si-Yuan Yu, Xue-Hua Wang
In this paper, we investigate second harmonic generation in a single hexagonal GaAs nanowire. An excellent frequency converter based on this nanowire excited using a femtosecond laser is demonstrated to operate over a range from 730 nm to 1960 nm, which is wider than previously reported ranges for nanowires in the literature. The converter always operates with a high conversion efficiency of ~10(-5) W(-1) which is ~10(3) times higher than that obtained from the surface of bulk GaAs. This nanoscale nolinear optical converter that simultaneously owns high efficiency and broad bandwidth may open a new way for application in imaging, bio-sensing and on-chip all-optical signal processing operations...
May 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28522530/high-harmonic-generation-in-graphene-enhanced-by-elliptically-polarized-light-excitation
#2
Naotaka Yoshikawa, Tomohiro Tamaya, Koichiro Tanaka
The electronic properties of graphene can give rise to a range of nonlinear optical responses. One of the most desirable nonlinear optical processes is high-harmonic generation (HHG) originating from coherent electron motion induced by an intense light field. Here, we report on the observation of up to ninth-order harmonics in graphene excited by mid-infrared laser pulses at room temperature. The HHG in graphene is enhanced by an elliptically polarized laser excitation, and the resultant harmonic radiation has a particular polarization...
May 19, 2017: Science
https://www.readbyqxmd.com/read/28513724/role-of-electronic-correlations-in-photoionization-of-no2-in-the-vicinity-of-the-2-a1-2-b2-conical-intersection
#3
Danilo S Brambila, Alex G Harvey, Karel Houfek, Zdeněk Mašín, Olga Smirnova
We present the first ab initio multi-channel photoionization calculations for NO2 in the vicinity of the (2)A1/(2)B2 conical intersection, for a range of nuclear geometries, using our newly developed set of tools based on the ab initio multichannel R-matrix method. Electronic correlation is included in both the neutral and the scattering states of the molecule via configuration interaction. Configuration mixing is especially important around conical intersections and avoided crossings, both pertinent for NO2, and manifests itself via significant variations in photoelectron angular distributions...
May 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28511012/nonlinear-optical-magnetism-revealed-by-second-harmonic-generation-in-nanoantennas
#4
Sergey S Kruk, Rocio Camacho-Morales, Lei Xu, Mohsen Rahmani, Daria A Smirnova, Lei Wang, Hark Hoe Tan, Chennupati Jagadish, Dragomir N Neshev, Yuri S Kivshar
Nonlinear effects at the nanoscale are usually associated with the enhancement of electric fields in plasmonic structures. Recently emerged new platform for nanophotonics based on high-index dielectric nanoparticles utilizes optically induced magnetic response via multipolar Mie resonances and provides novel opportunities for nanoscale nonlinear optics. Here, we observe strong second-harmonic generation from AlGaAs nanoantennas driven by both electric and magnetic resonances. We distinguish experimentally the contribution of electric and magnetic nonlinear response by analyzing the structure of polarization states of vector beams in the second-harmonic radiation...
May 22, 2017: Nano Letters
https://www.readbyqxmd.com/read/28507292/growth-properties-and-theoretical-analysis-of-m2livo4-m%C3%A2-%C3%A2-rb-cs-crystals-two-potential-mid-infrared-nonlinear-optical-materials
#5
Guopeng Han, Ying Wang, Xin Su, Zhihua Yang, Shilie Pan
Mid-Infrared nonlinear optical (Mid-IR NLO) crystals with excellent performances play a particularly important role for applications in areas such as telecommunications, laser guidance, and explosives detection. However, the design and growth of high performance Mid-IR NLO crystals with large NLO efficiency and high laser-damage threshold (LDT) still face numerous fundamental challenge. In this study, two potential Mid-IR NLO materials, Rb2LiVO4 (RLVO) and Cs2LiVO4 (CLVO) with noncentrosymmetric structures (Orthorhombic, Cmc21) were synthesized by high-temperature solution method...
May 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28504736/third-harmonic-blue-light-generation-from-kerr-clustered-combs-and-dispersive-waves
#6
Shun Fujii, Takumi Kato, Ryo Suzuki, Takasumi Tanabe
We demonstrated the deterministic generation of blue light emission (438 nm) via the third-harmonic process from an infrared pump by carefully engineering the dispersion of a high-quality-factor whispering gallery mode microcavity. We present two different approaches to obtaining broad bandwidth light. One is based on a clustered comb and the other employs a dispersive wave, and a broad Kerr comb spanning a half-octave is obtained. This allowed frequency conversion over a broad bandwidth ranging from 438 to 612 nm...
May 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28470531/assessment-of-population-and-ecm-production-using-multiphoton-microscopy-as-an-indicator-of-cell-viability
#7
Martin Vielreicher, Oliver Friedrich
Multiphoton microscopy allows continuous depth-resolved, nondestructive imaging of scaffold-seeded cells during cell or tissue culture. Spectrally separated images in high resolution can be provided while cells are conserved in their native state. Here we describe the seeding of mesenchymal stem cells to bacterial nanocellulose hydropolymer scaffolds followed by 2-channel imaging of cellular autofluorescence (AF) and collagen-I formation using second harmonic generation (SHG) signals. With this approach the simultaneous observation of the progression of cell morphology and production of extracellular matrix as hallmarks of viability and cell fitness is possible...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28468388/phase-matching-of-noncollinear-sum-and-difference-frequency-high-harmonic-generation-above-and-below-the-critical-ionization-level
#8
Jennifer L Ellis, Kevin M Dorney, Charles G Durfee, Carlos Hernández-García, Franklin Dollar, Christopher A Mancuso, Tingting Fan, Dmitriy Zusin, Christian Gentry, Patrik Grychtol, Henry C Kapteyn, Margaret M Murnane, Daniel D Hickstein
We investigate the macroscopic physics of noncollinear high harmonic generation (HHG) at high pressures. We make the first experimental demonstration of phase matching of noncollinear high-order-difference-frequency generation at ionization fractions above the critical ionization level, which normally sets an upper limit on the achievable cutoff photon energies. Additionally, we show that noncollinear high-order-sum-frequency generation requires much higher pressures for phase matching than single-beam HHG does, which mitigates the short interaction region in this geometry...
May 1, 2017: Optics Express
https://www.readbyqxmd.com/read/28463291/high-brightness-low-coherence-digital-holographic-microscopy-for-3d-visualization-of-an-in-vitro-sandwiched-biological-sample
#9
D G Abdelsalam, Takeshi Yasui
We achieve practically a bright-field digital holographic microscopy (DHM) configuration free from coherent noise for three-dimensional (3D) visualization of an in-vitro sandwiched sarcomere sample. Visualization of such sandwiched samples by conventional atomic force microscope (AFM) is impossible, while visualization using DHM with long coherent lengths is challenging. The proposed configuration is comprised of an ultrashort pulse laser source and a Mach-Zehnder interferometer in transmission. Periodically poled lithium niobate (PPLN) crystal was used to convert the fundamental beam by second harmonic generation (SHG) to the generated beam fit to the CCD camera used...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28454168/laser-waveform-control-of-extreme-ultraviolet-high-harmonics-from-solids
#10
Yong Sing You, Mengxi Wu, Yanchun Yin, Andrew Chew, Xiaoming Ren, Shima Gholam-Mirzaei, Dana A Browne, Michael Chini, Zenghu Chang, Kenneth J Schafer, Mette B Gaarde, Shambhu Ghimire
Solid-state high-harmonic sources offer the possibility of compact, high-repetition-rate attosecond light emitters. However, the time structure of high harmonics must be characterized at the sub-cycle level. We use strong two-cycle laser pulses to directly control the time-dependent nonlinear current in single-crystal MgO, leading to the generation of extreme ultraviolet harmonics. We find that harmonics are delayed with respect to each other, yielding an atto-chirp, the value of which depends on the laser field strength...
May 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/28454156/continuously-wavelength-tunable-high-harmonic-generation-via-soliton-dynamics
#11
Francesco Tani, Michael H Frosz, John C Travers, Philip St J Russell
We report the generation of high harmonics in a gas jet pumped by pulses self-compressed in a He-filled hollow-core photonic crystal fiber through the soliton effect. The gas jet is placed directly at the fiber output. As the energy increases, the ionization-induced soliton blueshift is transferred to the high harmonics, leading to emission bands that are continuously tunable from 17 to 45 eV.
May 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/28453957/a-magnetic-droplet-vaporization-approach-using-perfluorohexane-encapsulated-magnetic-mesoporous-particles-for-ultrasound-imaging-and-tumor-ablation
#12
Zhaogang Teng, Ronghui Wang, Yang Zhou, Michael Kolios, Yanjie Wang, Nan Zhang, Zhigang Wang, Yuanyi Zheng, Guangming Lu
Phase change agents consisting of low boiling point perfluorocarbon (PFC) compounds have attracted increasing attention for ultrasound contrast-enhanced imaging and tumor therapy. However, the refraction, acoustic shadowing, reverberation, or limited penetration depth hamper their practical applications through previously reported acoustic droplet vaporization (ADV) or optical droplet vaporization (ODV) technique. Herein, we demonstrate a magnetic droplet vaporization (MDV) approach by loading perflurohexane (PFH) in magnetic mesoporous particles with a hollow space to carry out ultrasound imaging and tumor ablation...
April 15, 2017: Biomaterials
https://www.readbyqxmd.com/read/28447616/high-order-harmonics-measured-by-the-photon-statistics-of-the-infrared-driving-field-exiting-the-atomic-medium
#13
N Tsatrafyllis, I K Kominis, I A Gonoskov, P Tzallas
High-order harmonics in the extreme-ultraviolet spectral range, resulting from the strong-field laser-atom interaction, have been used in a broad range of fascinating applications in all states of matter. In the majority of these studies the harmonic generation process is described using semi-classical theories which treat the electromagnetic field of the driving laser pulse classically without taking into account its quantum nature. In addition, for the measurement of the generated harmonics, all the experiments require diagnostics in the extreme-ultraviolet spectral region...
April 27, 2017: Nature Communications
https://www.readbyqxmd.com/read/28447398/a-suite-of-essential-biodiversity-variables-for-detecting-critical-biodiversity-change
#14
Dirk S Schmeller, Lauren V Weatherdon, Adeline Loyau, Alberte Bondeau, Lluis Brotons, Neil Brummitt, Ilse R Geijzendorffer, Peter Haase, Mathias Kuemmerlen, Corinne S Martin, Jean-Baptiste Mihoub, Duccio Rocchini, Hannu Saarenmaa, Stefan Stoll, Eugenie C Regan
Key global indicators of biodiversity decline, such as the IUCN Red List Index and the Living Planet Index, have relatively long assessment intervals. This means they, due to their inherent structure, function as late-warning indicators that are retrospective, rather than prospective. These indicators are unquestionably important in providing information for biodiversity conservation, but the detection of early-warning signs of critical biodiversity change is also needed so that proactive management responses can be enacted promptly where required...
April 26, 2017: Biological Reviews of the Cambridge Philosophical Society
https://www.readbyqxmd.com/read/28443939/magnetic-fano-resonance-induced-second-harmonic-generation-enhancement-in-plasmonic-metamolecule-rings
#15
Da-Jie Yang, Song-Jin Im, Gui-Ming Pan, Si-Jing Ding, Zhong-Jian Yang, Zhong-Hua Hao, Li Zhou, Qu-Quan Wang
The "artificial magnetic" resonance in plasmonic metamolecules extends the potential application of magnetic resonance from terahertz to optical frequency bypassing the problem of magnetic response saturation by replacing the conduction current with the ring displacement current. So far, the magnetic Fano resonance-induced nonlinearity enhancement in plasmonic metamolecule rings has not been reported. Here, we use the magnetic Fano resonance to enhance second-harmonic generation (SHG) in plasmonic metamolecule rings...
May 11, 2017: Nanoscale
https://www.readbyqxmd.com/read/28436654/crystal-phase-transitions-and-photocatalysis-in-supramolecular-scaffolds
#16
Roman V Kazantsev, Adam J Dannenhoffer, Adam S Weingarten, Brian T Phelan, Boris Harutyunyan, Taner Aytun, Ashwin Narayanan, Daniel J Fairfield, Job Boekhoven, Hiroaki Sai, Andrew Senesi, Pascual I O'Dogherty, Liam C Palmer, Michael J Bedzyk, Michael R Wasielewski, Samuel I Stupp
The energy landscape of a supramolecular material can include different molecular packing configurations that differ in stability and function. We report here on a thermally driven crystalline order transition in the landscape of supramolecular nanostructures formed by charged chromophore amphiphiles in salt-containing aqueous solutions. An irreversible transition was observed from a metastable to a stable crystal phase within the nanostructures. In the stable crystalline phase, the molecules end up organized in a short scroll morphology at high ionic strengths and as long helical ribbons at lower salt content...
April 24, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28436436/time-reversal-symmetry-breaking-hidden-order-in-sr2-ir-rh-o4
#17
Jaehong Jeong, Yvan Sidis, Alex Louat, Véronique Brouet, Philippe Bourges
Layered 5d transition iridium oxides, Sr2(Ir,Rh)O4, are described as unconventional Mott insulators with strong spin-orbit coupling. The undoped compound, Sr2IrO4, is a nearly ideal two-dimensional pseudospin-1/2 Heisenberg antiferromagnet, similarly to the insulating parent compound of high-temperature superconducting copper oxides. Using polarized neutron diffraction, we here report a hidden magnetic order in pure and doped Sr2(Ir,Rh)O4, distinct from the usual antiferromagnetic pseudospin ordering. We find that time-reversal symmetry is broken while the lattice translation invariance is preserved in the hidden order phase...
April 24, 2017: Nature Communications
https://www.readbyqxmd.com/read/28435961/single-photon-coulomb-explosion-of-methanol-using-broad-bandwidth-ultrafast-euv-pulses
#18
Itamar Luzon, Krishna Jagtap, Ester Livshits, Oleg Lioubashevski, Roi Baer, Daniel Strasser
Single-photon Coulomb explosion of methanol is instigated using the broad bandwidth pulse achieved through high-order harmonics generation. Using 3D coincidence fragment imaging of one molecule at a time, the kinetic energy release (KER) and angular distributions of the products are measured in different Coulomb explosion (CE) channels. Two-body CE channels breaking either the C-O or the C-H bonds are described as well as a proton migration channel forming H2O(+), which is shown to exhibit higher KER. The results are compared to intense-field Coulomb explosion measurements in the literature...
April 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28432315/experimental-evidence-of-fano-resonances-in-nanomechanical-resonators
#19
Stefano Stassi, Alessandro Chiadò, Giuseppe Calafiore, Gianluca Palmara, Stefano Cabrini, Carlo Ricciardi
Fano resonance refers to an interference between localized and continuum states that was firstly reported for atomic physics and solid-state quantum devices. In recent years, Fano interference gained more and more attention for its importance in metamaterials, nanoscale photonic devices, plasmonic nanoclusters and surface-enhanced Raman scattering (SERS). Despite such interest in nano-optics, no experimental evidence of Fano interference was reported up to now for purely nanomechanical resonators, even if classical mechanical analogies were referred from a theoretical point of view...
April 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28429023/probing-the-role-of-excited-states-in-ionization-of-acetylene
#20
Daniel Dundas, Peter Mulholland, Abigail Wardlow, Alejandro de la Calle
Ionization of acetylene by linearly-polarized, vacuum ultraviolet (VUV) laser pulses is modelled using time-dependent density functional theory. Several laser wavelengths are considered including one that produces direct ionization to the first excited cationic state while another excites the molecules to a Rydberg series incorporating an autoionizing state. We show that for the wavelengths and intensities considered, ionization is greatest whenever the molecule is aligned along the laser polarization direction...
April 21, 2017: Physical Chemistry Chemical Physics: PCCP
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