Read by QxMD icon Read

high harmonic generation

Nariyuki Saito, Nobuhisa Ishii, Teruto Kanai, Shuntaro Watanabe, Jiro Itatani
Long-wavelength lasers have great potential to become a new-generation drive laser for tabletop coherent light sources in the soft X-ray region. Because of the significantly low conversion efficiency from a long-wavelength light field to high-order harmonics, their pulse characterization has been carried out by measuring the carrier-envelope phase and/or spatial dependences of high harmonic spectra. However, these photon detection schemes, in general, have difficulty in obtaining information on the spectral phases, which is crucial to determine the temporal structures of high-order harmonics...
October 18, 2016: Scientific Reports
Ryan J Gallacher, Derek Keir, Nicholas Harmon, Graham Stuart, Sylvie Leroy, James O S Hammond, J-Michael Kendall, Atalay Ayele, Berhe Goitom, Ghebrebrhan Ogubazghi, Abdulhakim Ahmed
Melting of the mantle during continental breakup leads to magmatic intrusion and volcanism, yet our understanding of the location and dominant mechanisms of melt generation in rifting environments is impeded by a paucity of direct observations of mantle melting. It is unclear when during the rifting process the segmented nature of magma supply typical of seafloor spreading initiates. Here, we use Rayleigh-wave tomography to construct a high-resolution absolute three-dimensional shear-wave velocity model of the upper 250 km beneath the Afar triple junction, imaging the mantle response during progressive continental breakup...
October 18, 2016: Nature Communications
M Pang, W He, P St J Russell
We report a Tm-doped soliton fiber laser passively mode-locked by intense optoacoustic interactions in a short length of solid-core silica photonic crystal fiber (PCF) with a nanobore in core-center. A repetition rate of 1.446 GHz pulse is achieved, corresponding to the 52nd harmonic of the 27.8 MHz cavity round-trip frequency. Strong optoacoustic interactions in this PCF-based, Tm-doped fiber laser ensure stable and repeatable gigahertz-rate pulse train generation at 1.85 μm wavelength, with a high supermode noise suppression ratio and low pulse timing jitter...
October 1, 2016: Optics Letters
Alexei Smolyaninov, Mu-Han Yang, Lin Pang, Yeshaiahu Fainman
A high-density array of plasmonic coaxial nanoantennas is used to enhance the two-photon absorption (TPA) process in a conventional silicon photodetector from a mode-locked 76 MHz Ti:sapphire laser over a spectral range from 1340 to 1550 nm. This enhanced TPA was used to generate an interferometric autocorrelation trace of a 150 fs laser pulse. Unlike second-harmonic generation, this technique does not require phase matching or a bulky crystal and can be used on a low-cost integrated silicon platform over a wide range of near-IR wavelengths compatible with modern commercial tunable femtosecond sources...
October 1, 2016: Optics Letters
Erica Roitero, Federico Lasserre, Marc Anglada, Frank Mücklich, Emilio Jiménez-Piqué
OBJECTIVE: The aim of this work is to generate micrometric linear patterns with different topography on dental grade zirconia by means of UV laser interference and to assess the quality of the produced surface, both in term of the geometry produced and of the surface damage induced in the material. METHODS: The third harmonic of a Q-switched Nd:YAG laser (355nm, pulse duration of 10ns and repetition rate of 1Hz) was employed to pattern the surface of 3Y-TZP with micrometric-spaced lines...
October 10, 2016: Dental Materials: Official Publication of the Academy of Dental Materials
Gregory J Wright, Matthew C Coombs, R Glenn Hepfer, Brooke J Damon, Thierry H Bacro, Michael K Lecholop, Elizabeth H Slate, Hai Yao
Approximately 30% of temporomandibular joint (TMJ) disorders include degenerative changes to the articular disc, with sex-specific differences in prevalence and severity. Limited tensile biomechanical properties of human TMJ discs have been reported. Stress relaxation tests were conducted on TMJ disc specimens harvested bilaterally from six males and six females (68.9±7.9 years), with step-strain increments of 5%, 10%, 15%, 20% and 30%, at 1% strain-per-second. Stress versus strain plots were constructed, and Young׳s Modulus, Instantaneous Modulus and Relaxed Modulus were determined...
October 6, 2016: Journal of Biomechanics
Mingjun Xia, Xingxing Jiang, Zheshuai Lin, Rukang Li
A new nonlinear optical (NLO) material Bi3TeBO9 (BTBO) is successfully grown from high temperature solution method. BTBO crystallizes in a polar space group of P63 with a framework structure composed of [Bi3O9] blocks, with TeO6 and BO3 interconnection. It is interesting that in the BTBO structure three types of NLO-active units, including stereochemically active lone pair cations (Bi3+ cations), second-order Jahn-Teller distorted octahedra (TeO6 octahedra) and π-orbital planar groups (BO3 groups), simultaneously exist...
October 14, 2016: Journal of the American Chemical Society
Qiang Bian, Zhihua Yang, Ying Wang, Chao Cao, Shilie Pan
Searching for high performance materials for optical communication and laser industry in deep-ultraviolet (DUV) region has been the subject of considerable interest. Such materials by design from scratching on multi-component complex crystal systems are challenging. Here, we predict, through density function calculations and unbiased structure searching techniques, the formation of quaternary NaBeBO3 compounds at ambient pressure. Among the four low-energy phases, the P63/m structure exhibits a DUV cutoff edge of 20 nm shorter than α-BaB2O4 (189 nm) - the best-known DUV birefringent material...
October 13, 2016: Scientific Reports
Pierre Çarçabal, Dominique Descamps, Stéphane Petit, Yann Mairesse, Valérie Blanchet, Raluca Cireasa
5-Fluorouracil (5FU) is a radiosensitiser molecule routinely used in combined chemo- and radio-therapies to enhance and localize cancer treatments. We have employed ultra-short XUV pulses produced by high harmonic generation (HHG) as a pump pulse to study the dynamics underlying the photo-stability and the radiation damage of this molecule. This work shows that it is possible to resolve individual dynamics even when using unselected HH. By comparing the results with those obtained in the multiphoton absorption at 400 nm, we were able to identify the frequencies of the HH comb relevant to the recorded dynamics: HH5 and HH3...
September 22, 2016: Faraday Discussions
Barry D Bruner, Zdeněk Mašín, Matteo Negro, Felipe Morales, Danilo Brambila, Michele Devetta, Davide Faccialà, Alex G Harvey, Misha Ivanov, Yann Mairesse, Serguei Patchkovskii, Valeria Serbinenko, Hadas Soifer, Salvatore Stagira, Caterina Vozzi, Nirit Dudovich, Olga Smirnova
High harmonic generation (HHG) spectroscopy has opened up a new frontier in ultrafast science, where electronic dynamics can be measured on an attosecond time scale. The strong laser field that triggers the high harmonic response also opens multiple quantum pathways for multielectron dynamics in molecules, resulting in a complex process of multielectron rearrangement during ionization. Using combined experimental and theoretical approaches, we show how multi-dimensional HHG spectroscopy can be used to detect and follow electronic dynamics of core rearrangement on sub-laser cycle time scales...
September 26, 2016: Faraday Discussions
Seunghwoi Han, Hyunwoong Kim, Yong Woo Kim, Young-Jin Kim, Seungchul Kim, In-Yong Park, Seung-Woo Kim
Plasmonic high-harmonic generation (HHG) drew attention as a means of producing coherent extreme ultraviolet (EUV) radiation by taking advantage of field enhancement occurring in metallic nanostructures. Here a metal-sapphire nanostructure is devised to provide a solid tip as the HHG emitter, replacing commonly used gaseous atoms. The fabricated solid tip is made of monocrystalline sapphire surrounded by a gold thin-film layer, and intended to produce EUV harmonics by the inter- and intra-band oscillations of electrons driven by the incident laser...
October 10, 2016: Nature Communications
Daniel M Reich, Lars Bojer Madsen
We present a general theory of bicircular high-order-harmonic generation from N-fold rotationally symmetric molecules. Using a rotating frame of reference we predict the complete structure of the high-order-harmonic spectra for arbitrary driving frequency ratios and show how molecular symmetries can be directly identified from the harmonic signal. Our findings reveal that a characteristic fingerprint of rotational molecular symmetries can be universally observed in the ultrafast response of molecules to strong bicircular fields...
September 23, 2016: Physical Review Letters
Christopher A Mancuso, Kevin M Dorney, Daniel D Hickstein, Jan L Chaloupka, Jennifer L Ellis, Franklin J Dollar, Ronny Knut, Patrik Grychtol, Dmitriy Zusin, Christian Gentry, Maithreyi Gopalakrishnan, Henry C Kapteyn, Margaret M Murnane
Atoms undergoing strong-field ionization in two-color circularly polarized femtosecond laser fields exhibit unique two-dimensional photoelectron trajectories and can emit bright circularly polarized extreme ultraviolet and soft-x-ray beams. In this Letter, we present the first experimental observation of nonsequential double ionization in these tailored laser fields. Moreover, we can enhance or suppress nonsequential double ionization by changing the intensity ratio and helicity of the two driving laser fields to maximize or minimize high-energy electron-ion rescattering...
September 23, 2016: Physical Review Letters
Zhonghui Liu, Jian Ye
Creating plasmonic nanostructures with controllable Fano resonances is of great interest for a number of important applications including metamaterials and biosensors. Realizing double Fano resonances is even more challenging but may become favorable to the applications such as surface enhanced Raman scattering (SERS) and second harmonic generation (SHG). Here we have developed plasmonic metasurfaces consisting of a nanoring array and a metallic film separated by a dielectric spacer for the generation of double Fano resonances...
October 14, 2016: Nanoscale
Dane R Austin, Felicity McGrath, Lukas Miseikis, David Wood, Peter Hawkins, Allan S Johnson, Morgane Vacher, Zdeněk Mašín, Alex Harvey, Misha Ivanov, Olga Smirnova, Jon P Marangos
We theoretically study high-harmonic generation in toluene, ortho-xylene and fluorobenzene driven by a 1.8 μm ultrashort pulse. We find that the chemical substitutions have a strong influence on the amplitude and phase of the emission from the highest occupied molecular orbital, despite having a small influence on the orbital itself. We show that this influence is due to the tunnel ionization step, which depends critically on the sign and amplitude of the asymptotic part of the wave function. We discuss how these effects would manifest in phase-sensitive high-harmonic generation spectroscopy experiments...
September 14, 2016: Faraday Discussions
L R Mingabudinova, V V Vinogradov, V A Milichko, E Hey-Hawkins, A V Vinogradov
The last five years have witnessed a huge breakthrough in the creation and the study of the properties of a new class of compounds - metamaterials. The next stage of this technological revolution will be the development of active, controllable, and non-linear metamaterials, surpassing natural media as platforms for optical data processing and quantum information applications. However, scientists are constantly faced with the need to find new methods that can ensure the formation of quantum and non-linear metamaterials with higher resolution...
September 26, 2016: Chemical Society Reviews
Ádám Krolopp, Attila Csákányi, Dóra Haluszka, Dániel Csáti, Lajos Vass, Attila Kolonics, Norbert Wikonkál, Róbert Szipőcs
A novel, Yb-fiber laser based, handheld 2PEF/SHG microscope imaging system is introduced. It is suitable for in vivo imaging of murine skin at an average power level as low as 5 mW at 200 kHz sampling rate. Amplified and compressed laser pulses having a spectral bandwidth of 8 to 12 nm at around 1030 nm excite the biological samples at a ~1.89 MHz repetition rate, which explains how the high quality two-photon excitation fluorescence (2PEF) and second harmonic generation (SHG) images are obtained at the average power level of a laser pointer...
September 1, 2016: Biomedical Optics Express
Margaret T Butko, Ben Moree, Richard B Mortensen, Joshua Salafsky
There is a high demand for characterizing oligonucleotide structural changes associated with binding interactions, as well as identifying novel binders that modulate their structure and function. In this study, second-harmonic generation (SHG) was used to study RNA and DNA oligonucleotide conformational changes associated with ligand binding. For this purpose we developed an avidin-based biotin capture surface based on a supported lipid bilayer membrane. The technique was applied to two well-characterized aptamers, both of which undergo conformational changes upon binding either a protein or a small molecule ligand...
October 4, 2016: Analytical Chemistry
Breann Yanagisawa, Gabriel Ghiaur, B Douglas Smith, Richard J Jones
Considerable evidence suggests that rare leukemia cells with stem cell features, including self-renewal capacity and drug resistance, are primarily responsible for both disease maintenance and relapses. Traditionally, these so-called leukemia stem cells (LSCs) have been identified in the laboratory by their ability to engraft acute myeloid leukemia (AML) into immunocompromised mice. For many years, only those rare AML cells characterized by a hematopoietic stem cell (HSC) CD34(+)CD38(-) phenotype were believed capable of generating leukemia in immunocompromised mice...
September 28, 2016: Experimental Hematology
Matthew R Edwards, Julia M Mikhailova
We consider the efficiency limit of relativistic high-order-harmonic emission from solid targets achievable with tailored light fields. Using one-dimensional particle-in-cell simulations, the maximum energy conversion efficiency is shown to reach as high as 10% for the harmonics in the range of 80-200 eV and is largely independent of laser intensity and plasma density. The waveforms most effective at driving harmonics have a broad spectrum with a lower-frequency limit set by the width of the incident pulse envelope and an upper limit set by the relativistic plasma frequency...
September 16, 2016: Physical Review Letters
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"