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high harmonic generation

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https://www.readbyqxmd.com/read/28454168/laser-waveform-control-of-extreme-ultraviolet-high-harmonics-from-solids
#1
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
#2
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
#3
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
#4
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
#5
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
#6
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...
April 26, 2017: Nanoscale
https://www.readbyqxmd.com/read/28436654/crystal-phase-transitions-and-photocatalysis-in-supramolecular-scaffolds
#7
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
#8
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
#9
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
#10
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
#11
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
https://www.readbyqxmd.com/read/28418013/a-graphene-based-frequency-quadrupler
#12
Chuantong Cheng, Beiju Huang, Xurui Mao, Zanyun Zhang, Zan Zhang, Zhaoxin Geng, Ping Xue, Hongda Chen
Benefit from exceptional electrical transport properties, graphene receives worldwide attentions, especially in the domain of high frequency electronics. Due to absence of effective bandgap causing off-state the device, graphene material is extraordinarily suitable for analog circuits rather than digital applications. With this unique ambipolar behavior, graphene can be exploited and utilized to achieve high performance for frequency multipliers. Here, dual-gated graphene field-effect transistors have been firstly used to achieve frequency quadrupling...
April 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28409641/efficient-second-harmonic-generation-in-nanocrystalline-silicon-nanoparticles
#13
Sergey V Makarov, Mihail I Petrov, Urs Zywietz, Valentin Milichko, Dmitry Zuev, Natalia Lopanitsyna, Alexey Kuksin, Ivan Mukhin, George Zograf, Evgeniy Ubyivovk, Daria A Smirnova, Sergey Starikov, Boris N Chichkov, Yuri S Kivshar
Recent trends to employ high-index dielectric particles in nanophotonics are motivated by their reduced dissipative losses and large resonant enhancement of nonlinear effects at the nanoscale. Because silicon is a centrosymmetric material, the studies of nonlinear optical properties of silicon nanoparticles have been targeting primarily the third-harmonic generation effects. Here we demonstrate, both experimentally and theoretically, that resonantly excited nanocrystalline silicon nanoparticles fabricated by an optimized laser printing technique can exhibit strong second-harmonic generation (SHG) effects...
April 24, 2017: Nano Letters
https://www.readbyqxmd.com/read/28408758/super-tunable-broadband-up-conversion-of-a-high-power-cw-laser-in-an-engineered-nonlinear-crystal
#14
Ameneh Bostani, Amirhossein Tehranchi, Raman Kashyap
A specially-designed chirped periodically poled lithium niobate nonlinear crystal was fabricated with a phase-matching bandwidth as large as 50 nm for sum frequency generation to operate at room and higher temperatures. This device also benefits from insensitivity to laser frequency drift and fine alignment. The loosely-focused beam position of a high-power CW laser at around 1550 nm is optimized within the grating for maximum up-conversion efficiency, to realize a super-tunable source in the range of 770-778 nm by tuning a narrowband control signal over 30 nm in the communication band...
April 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28402622/broken-symmetry-induced-strong-nonlinear-optical-effects-in-spiral-ws2-nanosheets
#15
Xiaopeng Fan, Ying Jiang, Xiujuan Zhuang, Hongjun Liu, Tao Xu, Weihao Zheng, Peng Fan, Honglai Li, Xueping Wu, Xiaoli Zhu, Qinglin Zhang, Hong Zhou, Wei Hu, Xiao Wang, Litao Sun, Xiangfeng Duan, Anlian Pan
Transition metal dichalcogenides have provided a new stage to study the light-matter interaction and optical application at atomic scale for their ultrathin thickness and their appropriate bandgap in the visible region. Here, we report the strong nonlinear optical effects, including second harmonic generation (SHG) and third harmonic generation (THG) in spiral WS2 structures. SHG intensity quadratically increases with layer numbers, other than diminishing oscillation of 2H stacking TMDs. The contrary SHG behavior is attributed to the broken symmetry from twisted screw structures, revealed by aberration corrected transmission electronic microscope (AC-TEM) observation...
April 12, 2017: ACS Nano
https://www.readbyqxmd.com/read/28397809/second-harmonic-generation-imaging-of-corneal-stroma-after-infection-by-pseudomonas-aeruginosa
#16
Danielle M Robertson, Nathan A Rogers, W Matthew Petroll, Meifang Zhu
Pseudomonas aeruginosa is a pathogenic gram-negative organism that has the ability to cause blinding corneal infections following trauma and during contact lens wear. In this study, we investigated the directional movement and orientation of an invasive corneal isolate of P. aeruginosa in the corneal stroma during infection of ex vivo and in vivo rabbit corneas using multiphoton fluorescence and second harmonic generation (SHG) imaging. Ex vivo, rabbit corneas were subject to three partial thickness wounds prior to inoculation...
April 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28394900/acute-development-of-cortical-porosity-and-endosteal-na%C3%A3-ve-bone-formation-from-the-daily-but-not-weekly-short-term-administration-of-pth-in-rabbit
#17
Hiroshi Yamane, Aya Takakura, Yukari Shimadzu, Toshiyuki Kodama, Ji-Won Lee, Yukihiro Isogai, Toshinori Ishizuya, Ryoko Takao-Kawabata, Tadahiro Iimura
Teriparatide [human parathyroid hormone (1-34)], which exerts an anabolic effect on bone, is used for the treatment of osteoporosis in patients who are at a high risk for fracture. That the once-daily administration of teriparatide causes an increase in cortical porosity in animal models and clinical studies has been a matter of concern. However, it is not well documented that the frequency of administration and/or the total dose of teriparatide affect the cortical porosity. The present study developed 4 teriparatide regimens [20 μg/kg/day (D20), 40 μg/kg/day (D40), 140 μg/kg/week (W140) and 280 μg/kg/week (W280)] in the rabbit as a model animal with a well-developed Haversian system and osteons...
2017: PloS One
https://www.readbyqxmd.com/read/28394608/second-generation-triple-helical-peptide-inhibitors-of-matrix-metalloproteinases
#18
Manishabrata Bhowmick, Dorota Tokmina-Roszyk, Lillian Onwuha-Ekpete, Kelli Harmon, Trista Robichaud, Rita Fuerst, Roma Stawikowska, Bjorn Steffensen, William Roush, Hector R Wong, Gregg B Fields
The design of selective matrix metalloproteinase (MMP) inhibitors that also possess favorable solubility properties has proved to be especially challenging. A prior approach using collagen-model templates combined with transition state analogs produced a first generation of triple-helical peptide inhibitors (THPIs) that were effective in vitro against discrete members of the MMP family. These THPI constructs were also highly water-soluble. The present study sought improvements in the first generation THPIs by enhancing thermal stability and selectivity...
April 19, 2017: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28387014/weak-by-the-machines-muscle-motor-protein-dysfunction-ndash-a-side-effect-of-intensive-care-unit-treatment
#19
REVIEW
O Friedrich, S Diermeier, L Larsson
Intensive care interventions involve periods of mechanical ventilation, sedation and complete mechanical silencing of patients. Critical illness myopathy (CIM) is an ICU-acquired myopathy that is associated with limb muscle weakness, muscle atrophy, electrical silencing of muscle and motor-proteinopathy. The hallmark of CIM is a preferential muscle myosin loss due to increased catabolic and reduced anabolic activity. The ubiquitin-proteasome pathway plays an important role, apart from recently identified novel mechanisms affecting nonlysosomal protein degradation or autophagy...
April 7, 2017: Acta Physiologica
https://www.readbyqxmd.com/read/28381038/second-harmonic-generation-in-nano-structured-thin-film-lithium-niobate-waveguides
#20
Cheng Wang, Xiao Xiong, Nicolas Andrade, Vivek Venkataraman, Xi-Feng Ren, Guang-Can Guo, Marko Lončar
Integrated thin-film lithium niobate platform has recently emerged as a promising candidate for next-generation, high-efficiency wavelength conversion systems that allow dense packaging and mass-production. Here we demonstrate efficient, phase-matched second harmonic generation in lithographically-defined thin-film lithium niobate waveguides with sub-micron dimensions. Both modal phase matching in fixed-width waveguides and quasi-phase matching in periodically grooved waveguides are theoretically proposed and experimentally demonstrated...
March 20, 2017: Optics Express
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