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https://www.readbyqxmd.com/read/29864638/spectral-nonlinear-optical-and-optical-limiting-properties-of-l-phenylalanine-l-phenylalaninium-formate-single-crystal
#1
Suneetha Nagaradona, Rajan Babu Dhanakotti
l-Phenylalanine l-Phenylalaninium Formate (LPPF) is an organic nonlinear optical crystal with molecular formula C9 H11 NO2 ·C9 H12 NO2 + ·CHO2 - , was grown by solution growth, slow evaporation method. Single crystal XRD reveals that the title compound crystallizes in monoclinic system with the space group P21. The presence of functional groups was identified by FT-IR spectrum. UV-visible spectrum analysis shows that the crystal exhibits good optical transparency with a minimum cut-off wavelength of 200 nm...
October 5, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29722528/insights-into-laser-ablation-processes-of-heterogeneous-samples-toward-analysis-of-through-silicon-vias
#2
Pavel Moreno-García, Valentine Grimaudo, Andreas Riedo, Alena Cedeño López, Reto Wiesendanger, Marek Tulej, Cynthia Gruber, Emanuel Lörtscher, Peter Wurz, Peter Broekmann
State-of-the-art three-dimensional very large-scale integration (3D-VLSI) relies, among other factors, on the purity of high-aspect-ratio Cu interconnects such as through-silicon-vias (TSVs). Accurate spatial chemical analysis of electroplated TSV structures has been proven to be challenging due to their large aspect ratios and their multimaterial composition (Cu and Si) with distinct physical properties. Here, we demonstrate that these structures can be accurately analyzed by femtosecond (fs) laser beam ablation techniques in combination with ionization mass spectrometry (LIMS)...
June 5, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29532785/radiation-characterisation-and-dosimetric-measurements-of-a-femtosecond-pulsed-laser-ablation-system
#3
J Prieto-Pena, F Gómez, D M González-Castaño, M T Flores-Arias, J Arines, C Bao-Varela, F Cambronero-López, A Martínez Maqueira
This work describes the radiation characterisation and dosimetric measurements performed on the low-energy micromachining station of the femtosecond STELA (Santiago TErawatt LAser) at the University of Santiago de Compostela (Spain). For this aim, ionisation chambers, solid state detectors, and radiochromic films were used. The results show the emission of pulsed x-ray produced by laser-accelerated electrons from the ablated material exhibiting both bremsstrahlung and characteristic radiation. Although this radiation was produced unintentionally, a high superficial dose rate can be achieved...
June 2018: Journal of Radiological Protection: Official Journal of the Society for Radiological Protection
https://www.readbyqxmd.com/read/29462711/exogenous-mineralization-of-hard-tissues-using-photo-absorptive-minerals-and-femto-second-lasers-the-case-of-dental-enamel
#4
A D Anastasiou, S Strafford, C L Thomson, J Gardy, T J Edwards, M Malinowski, S A Hussain, N K Metzger, A Hassanpour, C T A Brown, A P Brown, M S Duggal, A Jha
A radical new methodology for the exogenous mineralization of hard tissues is demonstrated in the context of laser-biomaterials interaction. The proposed approach is based on the use of femtosecond pulsed lasers (fs) and Fe3+ -doped calcium phosphate minerals (specifically in this work fluorapatite powder containing Fe2 O3 nanoparticles (NP)). A layer of the synthetic powder is applied to the surface of eroded bovine enamel and is irradiated with a fs laser (1040 nm wavelength, 1 GHz repetition rate, 150 fs pulse duration and 0...
April 15, 2018: Acta Biomaterialia
https://www.readbyqxmd.com/read/29328276/femto-nano-second-switchable-passively-mode-locked-fiber-laser-with-analytic-modeling-by-the-cubic-quintic-ginzburg-landau-equation
#5
Wen-Hsuan Kuan, Li-Ting Kao, Jing-Yun Wang, Kuei-Huei Lin
We report a passively mode-locked erbium-doped fiber laser with pulse widths switchable from 473 fs to 76.8 ns, where the fundamental mode-locking, noise-like pulse, nanosecond mode-locking, and dual-width mode-locking (DML) are obtained by adjusting a polarization controller. Co-existence of femto- and nano-second pulses in DML is attributed to the gain balancing. Analytic modeling of the fiber laser with the cubic-quintic Ginzburg-Landau equation is presented, in which the pulse widths are calculated as functions of dispersion, self-phase modulation (SPM), cubic saturable absorption (SA), and quintic SA...
January 15, 2018: Optics Letters
https://www.readbyqxmd.com/read/29304077/ideal-parameters-for-femto-second-laser-assisted-anterior-capsulotomy-animal-studies
#6
Min-Ji Kang, Yong-Eun Lee, Jun-Sub Choi, Choun-Ki Joo
In femtosecond laser-assisted cataract surgery, the parameter such as horizontal spot spacing and energy level can be adjusted. Although there have been several studies reported on various laser systems, showing the effects of varying energy levels and horizontal spot spacing on lens capsulotomy cut edges, none have been reported on the Catalys laser system (Abbott Medical Optics, Inc., Santa Ana, CA). The aim of this study is to evaluate, using scanning electron microscopy (SEM), the quality of the cut edges of the laser lens capsulotomy obtained using the Catalys Laser System, using different horizontal spot spacing and energy levels, and to determine the ideal parameters based on SEM results...
2018: PloS One
https://www.readbyqxmd.com/read/29123674/characterization-of-temporal-coherence-of-hard-x-ray-free-electron-laser-pulses-with-single-shot-interferograms
#7
Taito Osaka, Takashi Hirano, Yuki Morioka, Yasuhisa Sano, Yuichi Inubushi, Tadashi Togashi, Ichiro Inoue, Kensuke Tono, Aymeric Robert, Kazuto Yamauchi, Jerome B Hastings, Makina Yabashi
Temporal coherence is one of the most fundamental characteristics of light, connecting to spectral information through the Fourier transform relationship between time and frequency. Interferometers with a variable path-length difference (PLD) between the two branches have widely been employed to characterize temporal coherence properties for broad spectral regimes. Hard X-ray interferometers reported previously, however, have strict limitations in their operational photon energies, due to the specific optical layouts utilized to satisfy the stringent requirement for extreme stability of the PLD at sub-ångström scales...
November 1, 2017: IUCrJ
https://www.readbyqxmd.com/read/28789006/lightning-rod-resonance-of-a-plasmonic-near-field-transducer
#8
Chubing Peng, Kaspar D Ko
We demonstrate the lightning-rod resonance of a lollipop near-field transducer integrated in magnetic writer for heat-assisted magnetic recording by collecting the two-photon excited photoluminescence (TPL) signal when excited by a pulsed femto-second fiber laser tuned to the desired mode resonance. The lollipop transducer consists of a round disk and a protruding peg to take advantage of the lightning-rod effect. It is found that the TPL signal is extremely sensitive to the peg length where even a 3-5 nm deviation from the optimal peg length halves the TPL signal...
June 26, 2017: Optics Express
https://www.readbyqxmd.com/read/28747621/evaluation-of-biomechanical-changes-in-myopia-patients-with-unsatisfactory-corneas-after-femto-second-laser-in-situ-keratomileusis-fs-lasik-concurrent-with-accelerated-corneal-collagen-cross-linking-using-corvis-st-two-year-follow-up-results
#9
Weiwei Xu, Ye Tao, Liqiang Wang, Yifei Huang
BACKGROUND Some myopia patients with unsatisfactory corneas consider corneal refractive surgery for different reasons. Accelerated corneal collagen crosslinking (ACXL) is an effective method to enhance the resistance of the cornea. The present investigation was designed to evaluate the changes of biomechanical properties in patients with myopia and thin corneas after femtosecond-laser in situ keratomileusis (FS-LASIK) concurrent with ACXL. MATERIAL AND METHODS A prospective study was designed. A total of 22 eyes of 11 myopia astigmatism patients with unsatisfactory corneas were enrolled...
July 27, 2017: Medical Science Monitor: International Medical Journal of Experimental and Clinical Research
https://www.readbyqxmd.com/read/28660920/faradaic-oxygen-evolution-from-srtio-3-under-nano-and-femto-second-pulsed-light-excitation
#10
D J Aschaffenburg, X Chen, T Cuk
During photocatalytic water oxidation, n-SrTiO3 (100) demonstrated near 100% Faradaic efficiency for O2 evolution with nano- (30 ns) and femto- (150 fs) second pulsed laser excitation of the band gap, despite surface rearrangements attributed to the high peak power (300 MW cm-2 ). Therefore, these results establish a methodology for tracking intermediates of the water oxidation cycle at the n-SrTiO3 (100) surface from the picosecond time scales of charge transfer through to the millisecond time scales of O2 evolution...
June 29, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28629164/cataract-surgery-performed-by-high-frequency-ldv-z8-femtosecond-laser-safety-efficacy-and-its-physical-properties
#11
Bojan Pajic, Zeljka Cvejic, Brigitte Pajic-Eggspuehler
BACKGROUND: The aim of our study was to investigate the safety and efficacy of the LDV Z8 femtosecond laser in cataract surgery compared to the conventional procedure. METHODS: This prospective study was performed at the Swiss Eye Research Foundation, Eye Clinic ORASIS, Reinach, Switzerland. The study included 130 eyes from 130 patients: 68 treated with femtosecond laser-assisted cataract surgery (FLACS) using the FEMTO LDV Z8 and 62 treated with conventional phacoemulsification...
June 18, 2017: Sensors
https://www.readbyqxmd.com/read/28085824/laser-damage-properties-of-broadband-low-dispersion-mirrors-in-sub-nanosecond-laser-pulse
#12
Jinlong Zhang, Xiaoqing Bu, Hongfei Jiao, Bin Ma, Xinbin Cheng, Zhangshan Wang
Broadband low dispersion (BBLD) mirrors are an essential component in femto-second (fs) pulse laser systems. We designed and produced Ta<sub>2</sub>O<sub>5</sub>-HfO<sub>2</sub>/SiO<sub>2</sub> composite quarter-wave and non-quarter-wave HfO<sub>2</sub>/SiO<sub>2</sub> BBLD mirrors for the 30fs petawatt laser system. The laser damage properties of the BBLD mirrors were investigated in an uncompressed sub-nanosecond laser pulse. It showed that the Ta<sub>2</sub>O<sub>5</sub>-HfO<sub>2</sub>/SiO<sub>2</sub> composite BBLD mirror possessed higher LIDT due to the low electric-field intensity (EFI) in the case of the coating without artificial nodules...
January 9, 2017: Optics Express
https://www.readbyqxmd.com/read/28059773/attosecond-physics-at-the-nanoscale
#13
M F Ciappina, J A Pérez-Hernández, A S Landsman, W A Okell, S Zherebtsov, B Förg, J Schötz, L Seiffert, T Fennel, T Shaaran, T Zimmermann, A Chacón, R Guichard, A Zaïr, J W G Tisch, J P Marangos, T Witting, A Braun, S A Maier, L Roso, M Krüger, P Hommelhoff, M F Kling, F Krausz, M Lewenstein
Recently two emerging areas of research, attosecond and nanoscale physics, have started to come together. Attosecond physics deals with phenomena occurring when ultrashort laser pulses, with duration on the femto- and sub-femtosecond time scales, interact with atoms, molecules or solids. The laser-induced electron dynamics occurs natively on a timescale down to a few hundred or even tens of attoseconds (1 attosecond  =  1 as  =  10-18 s), which is comparable with the optical field. For comparison, the revolution of an electron on a 1s orbital of a hydrogen atom is  ∼152 as...
May 2017: Reports on Progress in Physics
https://www.readbyqxmd.com/read/27643602/-experience-with-introduction-of-smile-learning-phase-of-our-first-200-treatments
#14
S Taneri, S Kießler, A Rost, B Dick
Background  Small Incision Lenticule Extraction (SMILE) is a relatively new surgical method to correct myopia and myopic astigmatism. Although considered to be safe and effective, it is not yet popular. Potential reasons for its limited use could be that surgeons fear inferior results and a higher complication rate in the learning phase. Therefore we present our experiences with the treatment of our first 200 eyes, with special attention to refraction results, complications, and learning curve. Patients and Methods  200 myopic or myopic astigmatic eyes of 102 patients were treated with SMILE...
January 2017: Klinische Monatsblätter Für Augenheilkunde
https://www.readbyqxmd.com/read/27466066/all-optical-switching-in-granular-ferromagnets-caused-by-magnetic-circular-dichroism
#15
Matthew O A Ellis, Eric E Fullerton, Roy W Chantrell
Magnetic recording using circularly polarised femto-second laser pulses is an emerging technology that would allow write speeds much faster than existing field driven methods. However, the mechanism that drives the magnetisation switching in ferromagnets is unclear. Recent theories suggest that the interaction of the light with the magnetised media induces an opto-magnetic field within the media, known as the inverse Faraday effect. Here we show that an alternative mechanism, driven by thermal excitation over the anisotropy energy barrier and a difference in the energy absorption depending on polarisation, can create a net magnetisation over a series of laser pulses in an ensemble of single domain grains...
July 28, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27414182/single-cdte-nanowire-optical-correlator-for-femtojoule-pulses
#16
Chenguang Xin, Shaoliang Yu, Qingyang Bao, Xiaoqin Wu, Bigeng Chen, Yipei Wang, Yingxin Xu, Zongyin Yang, Limin Tong
On the basis of the transverse second harmonic generation (TSHG) in a highly nonlinear subwavelength-diameter CdTe nanowire, we demonstrate a single-nanowire optical correlator for femto-second pulse measurement with pulse energy down to femtojoule (fJ) level. Pulses to be measured were equally split and coupled into two ends of a suspending nanowire via tapered optical fibers. The couterpropagating pulses meet each other around the central area of the nanowire, and emit TSHG signal perpendicular to the axis of the nanowire...
August 10, 2016: Nano Letters
https://www.readbyqxmd.com/read/27370440/1-hz-linewidth-ti-sapphire-laser-as-local-oscillator-for-40-ca-optical-clocks
#17
Wu Bian, Yao Huang, Hua Guan, Peiliang Liu, Longsheng Ma, Kelin Gao
A Ti:sapphire laser at 729 nm is frequency stabilized to an ultra-stable ultra-low thermal expansion coefficient (ULE) cavity by means of Pound-Drever-Hall method. An acousto-optic modulator is used as the fast frequency feedback component. 1 Hz linewidth and 2 × 10(-15) frequency stability at 1-100 s are characterized by optical beating with a separated Fabry-Perot cavity stabilized diode laser. Compared to the universal method that the error signal feedback to inject current of a diode laser, this scheme is demonstrated to be simple and also effective for linewidth narrowing...
June 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27099462/clinical-outcomes-using-standard-phacoemulsification-and-femtosecond-laser-assisted-surgery-with-toric-intraocular-lenses
#18
Arnaldo Espaillat, Obniel Pérez, Richard Potvin
PURPOSE: To compare the 1-month and 1-year results of toric intraocular lens (IOL) implantation with standard (manual) phacoemulsification vs femtosecond laser-assisted surgery. PATIENTS AND METHODS: Refractive data, visual acuity data, and ocular aberration measured with a wavefront aberrometer were collected for two groups of patients from one site. The first group had standard phacoemulsification, while the second group had femtosecond laser-assisted surgery, and both groups were implanted with toric IOLs, either monofocal or multifocal...
2016: Clinical Ophthalmology
https://www.readbyqxmd.com/read/26481604/ultrafast-electronic-state-conversion-at-room-temperature-utilizing-hidden-state-in-cuprate-ladder-system
#19
R Fukaya, Y Okimoto, M Kunitomo, K Onda, T Ishikawa, S Koshihara, H Hashimoto, S Ishihara, A Isayama, H Yui, T Sasagawa
Photo-control of material properties on femto- (10(-15)) and pico- (10(-12)) second timescales at room temperature has been a long-sought goal of materials science. Here we demonstrate a unique ultrafast conversion between the metallic and insulating state and the emergence of a hidden insulating state by tuning the carrier coherence in a wide temperature range in the two-leg ladder superconductor Sr(14-x)Ca(x)Cu24O41 through femtosecond time-resolved reflection spectroscopy. We also propose a theoretical scenario that can explain the experimental results...
2015: Nature Communications
https://www.readbyqxmd.com/read/26417526/fast-single-photon-avalanche-photodiode-based-time-resolved-diffuse-optical-tomography-scanner
#20
Ying Mu, Mark Niedre
Resolution in diffuse optical tomography (DOT) is a persistent problem and is primarily limited by high degree of light scatter in biological tissue. We showed previously that the reduction in photon scatter between a source and detector pair at early time points following a laser pulse in time-resolved DOT is highly dependent on the temporal response of the instrument. To this end, we developed a new single-photon avalanche photodiode (SPAD) based time-resolved DOT scanner. This instrument uses an array of fast SPADs, a femto-second Titanium Sapphire laser and single photon counting electronics...
September 1, 2015: Biomedical Optics Express
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