keyword
MENU ▼
Read by QxMD icon Read
search

Pulse

keyword
https://www.readbyqxmd.com/read/28438007/high-speed-cleaving-of-crystals-with-ultrafast-bessel-beams
#1
L Rapp, R Meyer, L Furfaro, C Billet, R Giust, F Courvoisier
We develop a novel concept for ultra-high speed cleaving of crystalline materials with femtosecond lasers. Using Bessel beams in single shot, fracture planes can be induced nearly all along the Bessel zone in sapphire. For the first time, we show that only for a pulse duration below 650 fs, a single fracture can be induced in sapphire, while above this duration, cracks appear in all crystallographic orientations. We determine the influential parameters which are polarization direction, crystallographic axes and scanning direction...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28438002/hot-luminescence-from-gold-nanoflowers-and-its-application-in-high-density-optical-data-storage
#2
Yunbao Zheng, Haiying Liu, Jin Xiang, Qiaofeng Dai, Min Ouyang, Shaolong Tie, Sheng Lan
Gold nanoflowers with feature sizes ranging from several tenths to several hundred nanometers were synthesized by using the one-pot method. They were formed by the self-organization of gold nanoparticles of several nanometers and exhibited broad extinction spectra in the near infrared spectral range. Randomly distributed hot spots originating from the strongly localized modes were generated in gold nanoflowers and their appearances exhibited strong dependences on both the polarization and wavelength of the excitation light...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437994/high-speed-asynchronous-optical-sampling-based-on-ghz-yb-kyw-oscillators
#3
C Li, N Krauß, G Schäfer, L Ebner, O Kliebisch, J Schmidt, S Winnerl, M Hettich, T Dekorsy
A low-cost scheme of high-speed asynchronous optical sampling based on Yb:KYW oscillators is reported. Two GHz diode-pumped oscillators with a slight pulse repetition rate offset serve as pump and probe source, respectively. The temporal resolution of this system is limited to 500 fs mainly by the pulse duration of the oscillators and also by relative timing jitter between the oscillators. A near-shot-noise noise floor around 10<sup>-6</sup> (∆R/R) is obtained within a data acquisition time of a few seconds...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437977/polymer-optical-fiber-bragg-grating-inscription-with-a-single-uv-laser-pulse
#4
A Pospori, C A F Marques, O Bang, D J Webb, P André
We experimentally demonstrate the first polymer optical fiber Bragg grating inscribed with only one krypton fluoride laser pulse. The device has been recorded in a single-mode poly(methyl methacrylate) optical fiber, with a core doped with benzyl dimethyl ketal for photosensitivity enhancement. One laser pulse with a duration of 15 ns, which provide energy density of 974 mJ/cm<sup>2</sup>, is adequate to introduce a refractive index change of 0.74×10<sup>-4</sup> in the fiber core. After the exposure, the reflectivity of the grating increases for a few minutes following a second order exponential saturation...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437973/1867-2010-nm-tunable-femtosecond-thulium-doped-all-fiber-laser
#5
Biao Sun, Jiaqi Luo, Zhiyu Yan, Kun Liu, Junhua Ji, Ying Zhang, Qi Jie Wang, Xia Yu
We propose and demonstrate a broadly wavelength tunable mode-locked thulium-doped all-fiber laser, delivering sub-400 femtosecond (fs) pulses and tuning from 1867 nm to 2010 nm. The tunable range of 143 nm, to our best knowledge, is the widest in the femtosecond mode-locked thulium-doped fiber lasers (TDFLs). The broadly tunable range and femtosecond pulse oscillation attribute to the large free spectral range and bandwidth of the fiber-based Lyot filter, benefiting from the hybrid device based compact configuration...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437966/energy-scaling-and-extended-tunability-of-terahertz-wave-parametric-oscillator-with-mgo-doped-near-stoichiometric-linbo-sub-3-sub-crystal
#6
Yuye Wang, Longhuang Tang, Degang Xu, Chao Yan, Yixin He, Jia Shi, Dexian Yan, Hongxiang Liu, Meitong Nie, Jiachen Feng, Jianquan Yao
A widely tunable, high-energy terahertz wave parametric oscillator based on 1 mol. % MgO-doped near-stoichiometric LiNbO<sub>3</sub> crystal has been demonstrated with 1064 nm nanosecond pulsed laser pumping. The tunable range of 1.16 to 4.64 THz was achieved. The maximum THz wave output energy of 17.49 μJ was obtained at 1.88 THz under the pump energy of 165 mJ/pulse, corresponding to the THz wave conversion efficiency of 1.06 × 10<sup>-4</sup> and the photon conversion efficiency of 1...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437963/raman-gain-and-femtosecond-laser-induced-damage-of-ge-as-s-chalcogenide-glasses
#7
Yan Zhang, Yinsheng Xu, Chenyang You, Dong Xu, Junzhou Tang, Peiqing Zhang, Shixun Dai
Chemical stoichiometric Ge-As-S glasses were prepared, and their thermal properties, refractive index (n), optical bandgap, Raman gain, and femtosecond laser damage were examined. Results revealed that the n and density (ρ) of the glasses decreased as Ge concentration increased, whereas the bandgap and glass transition temperature (Tg) increased. The Raman gain coefficients (g<sub>R</sub>) of the samples were calculated on the basis of spontaneous Raman scattering spectra. g<sub>R</sub> decreased from 2...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437962/rapidly-reconfigurable-high-fidelity-optical-arbitrary-waveform-generation-in-heterogeneous-photonic-integrated-circuits
#8
Shaoqi Feng, Chuan Qin, Kuanping Shang, Shibnath Pathak, Weicheng Lai, Binbin Guan, Matthew Clements, Tiehui Su, Guangyao Liu, Hongbo Lu, Ryan P Scott, S J Ben Yoo
This paper demonstrates rapidly reconfigurable, high-fidelity optical arbitrary waveform generation (OAWG) in a heterogeneous photonic integrated circuit (PIC). The heterogeneous PIC combines advantages of high-speed indium phosphide (InP) modulators and low-loss, high-contrast silicon nitride (Si<sub>3</sub>N<sub>4</sub>) arrayed waveguide gratings (AWGs) so that high-fidelity optical waveform syntheses with rapid waveform updates are possible. The generated optical waveforms spanned a 160 GHz spectral bandwidth starting from an optical frequency comb consisting of eight comb lines separated by 20 GHz channel spacing...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437960/wind-ranging-and-velocimetry-with-low-peak-power-and-long-duration-modulated-laser
#9
Eiichi Yoshikawa, Tomoo Ushio
A novel approach to simultaneous wind ranging and velocimetry using low peak power, long-duration modulated laser pulse transmissions is proposed. Received signals backscattered by aerosol particles are processed by a multi-reference matched-filter (MRMF) which performs matched filter processing between the received signal and several reference signals in parallel and outputs a range-velocity profile of received power. Ranging and velocimetry are performed simultaneously by estimating received power, radial velocity, and velocity dispersion from a velocity profile at an arbitrary range in the range-velocity profile...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437959/high-average-power-2-%C3%AE-m-femtosecond-optical-parametric-oscillator-synchronously-pumped-by-a-thin-disk-mode-locked-laser
#10
T Petersen, J D Zuegel, J Bromage
A high-energy, extended-cavity femtosecond BiBO optical parametric oscillator synchronously pumped by a 1.0-ps, 1030-nm Yb:YAG, thin-disk pump laser is presented. The oscillator operated near degeneracy in a noncollinear interaction geometry, producing signal wavelength tunability from 1.99 to 2.20 μm. The signal pulses have an average power exceeding 2 W, producing 455-fs pulses at 7.08 MHz with energies up to 350 nJ, showing increased potential for tunable sources of scalable ultrafast pulses in the infrared...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437957/widely-wavelength-tunable-gain-switched-er-sup-3-sup-doped-zblan-fiber-laser-around-2-8-%C3%AE-m
#11
Chen Wei, Hongyu Luo, Hongxia Shi, YanJia Lyu, Han Zhang, Yong Liu
In this paper, we demonstrate a wavelength widely tunable gain-switched Er<sup>3+</sup>-doped ZBLAN fiber laser around 2.8 μm. The laser can be tuned over 170 nm (2699 nm~2869.9 nm) for various pump power levels, while maintaining stable μs-level single-pulse gain-switched operation with controllable output pulse duration at a selectable repetition rate. To the best of our knowledge, this is the first wavelength tunable gain-switched fiber laser in the 3 μm spectral region with the broadest tuning range (doubling the record tuning range) of the pulsed fiber lasers around 3 μm...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437955/cyclic-coding-for-brillouin-optical-time-domain-analyzers-using-probe-dithering
#12
Haritz Iribas, Alayn Loayssa, Florian Sauser, Miguel Llera, Sébastien Le Floch
We study the performance limits of mono-color cyclic coding applied to Brillouin optical time-domain analysis (BOTDA) sensors that use probe wave dithering. BOTDA analyzers with dithering of the probe use a dual-probe-sideband setup in which an optical frequency modulation of the probe waves along the fiber is introduced. This avoids non-local effects while keeping the Brillouin threshold at its highest level, thus preventing the spontaneous Brillouin scattering from generating noise in the deployed sensing fiber...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437952/real-time-observation-of-round-trip-resolved-spectral-dynamics-in-a-stabilized-fs-fiber-laser
#13
Bowen Li, Ying Yu, Xiaoming Wei, Yiqing Xu, Kevin K Tsia, Kenneth K Y Wong
Fiber-stretcher based phase-lock loop (PLL) is a mature technique in fiber mode-locked lasers for repetition-rate stabilization. However, undesired side effects may be induced if not properly handled, which is easily overlooked owing to the lack of single-shot spectral analyzers. Thanks to the ultrafast spectral analyzing capability of optical time-stretch, an intriguing spectral dynamics is observed in a repetition-rate-stabilized nonlinear polarization rotation (NPR) mode-locked laser. Under the dynamic state, the optical spectra of pulses undergo dramatic evolution in every round trip while the pulse energy is relatively constant...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437920/cmos-integrated-gan-led-array-for-discrete-power-level-stepping-in-visible-light-communications
#14
Alexander D Griffiths, Mohamed Sufyan Islim, Johannes Herrnsdorf, Jonathan J D McKendry, Robert Henderson, Harald Haas, Erdan Gu, Martin D Dawson
We report a CMOS integrated micro-LED array capable of generating discrete optical output power levels. A 16 × 16 array of individually addressable pixels are on-off controlled through parallel logic signals. With carefully selected groups of LEDs driven together, signals suitable for discrete transmission schemes are produced. The linearity of the device is assessed, and data transmission using pulse amplitude modulation (PAM) and orthogonal frequency division multiplexing (OFDM) is performed. Error-free transmission at a symbol rate of 100 MSamples/s is demonstrated with 4-PAM, yielding a data rate of 200 Mb/s...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437908/ionization-degree-measurement-in-the-gain-medium-of-a-hydrocarbon-free-rubidium-vapor-laser-operating-in-pulsed-and-cw-modes
#15
Xiaofan Zhao, Zining Yang, Weihong Hua, Hongyan Wang, Xiaojun Xu
Although the diode pumped alkali laser (DPAL) works in a three-level scheme, higher energy-state excitation and ionization processes exist during operation, which may lead to deleterious effects on laser performance. In this paper, we report the ionization degree measurement in the gain medium of an operational hydrocarbon-free Rb DPAL by using the optogalvanic method. The results show that, at the pulsed mode with a duration of ~1 ms, a maximal ionization degree of ~0.06% is obtained at a pump power of 140 W...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437905/amplitude-modulation-of-femtosecond-laser-pulses-in-the-megahertz-range-for-frequency-multiplexed-two-photon-imaging
#16
Dmitri Tsyboulski, Natalia Orlova, Peter Saggau
We present a frequency-multiplexed multi-site two-photon imaging method utilizing amplitude modulation of femtosecond laser pulses in the MHz range to tag each excitation beam and the corresponding fluorescence signals with specific frequencies. The frequency tags are generated with an interferometric scheme employing acousto-optic deflectors (AODs) to achieve precise spatial overlap of femtosecond laser pulses with periodically varying phase shift. Creating matching excitation beam patterns in each interferometer arm using multiple AOD driving frequencies, and subsequently overlapping these matching patterns, results in multiple encoded excitation beams with unique beat frequencies available for scanning...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437903/real-time-broadband-radio-frequency-spectrum-analyzer-based-on-parametric-spectro-temporal-analyzer-pasta
#17
Liao Chen, Yuhua Duan, Haidong Zhou, Xi Zhou, Chi Zhang, Xinliang Zhang
A real-time broadband radio frequency (RF) spectrum analyzer is proposed and experimentally demonstrated to rapidly measure the RF spectrum of broadband optical signal. Cross phase modulation in the highly-nonlinear fiber is used to convert the RF spectrum carried by the pump to the optical spectrum of the probe signal, then the optical spectrum is real-time analyzed with the parametric spectro-temporal analyzer (PASTA) technology. The system performances are investigated in detail, including bandwidth, resolution, frame rate, and dynamic range...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437814/assessment-of-early-cardiovascular-risk-in-children-and-adolescents-with-essential-hypertension
#18
Andreja Stelcar, Evgenija Homsak, Natasa Marcun Varda
The aim of our study was to investigate some early markers of hypertensive target organ damage in hypertensive children and adolescents, and to detect those showing most prominent clinical significance. We included 100 children with essential hypertension (EH) and 50 age-matched healthy control children, and evaluated left ventricular mass (LVM), intima-media thickness in the carotid arteries (IMT), pulse wave velocity (PWV), microalbuminuria, biochemical parameters and some adipokines. Statistically significant differences between the 2 groups were observed for HDL-cholesterol, LDL-cholesterol, triglycerides, insulin, uric acid, glucose, apolipoprotein A1, and total adiponectin...
April 24, 2017: Klinische Pädiatrie
https://www.readbyqxmd.com/read/28437700/nanomolar-electrochemical-detection-of-caffeic-acid-in-fortified-wine-samples-based-on-gold-palladium-nanoparticles-decorated-graphene-flakes
#19
Kokulnathan Thangavelu, Nehru Raja, Shen-Ming Chen, Wei-Cheng Liao
Amalgamation of noble metal nanomaterials on graphene flakes potentially paves one way to improve their physicochemical properties. This paper deals with the simultaneous electrochemical deposition of gold and palladium nanoparticles on graphene flakes (Au/PdNPs-GRF) for the sensitive determination of caffeic acid (CA). The physiochemical properties of the prepared Au/PdNPs-GRF was characterized by using numerous analytical techniques such as scanning electron microscopy, electron dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray powder diffraction, Raman spectroscopy and electrochemical impedance spectroscopy...
April 13, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28437230/high-diversity-of-antimicrobial-resistance-genes-class-1-integrons-and-genotypes-of-multidrug-resistant-escherichia-coli-in-beef-carcasses
#20
Chih-Ming Chen, Se-Chin Ke, Chia-Ru Li, Ying-Chen Wu, Ter-Hsin Chen, Chih-Ho Lai, Xin-Xia Wu, Lii-Tzu Wu
Multidrug-resistant Escherichia coli can contaminate food meat during processing and cause human infection. Phenotypic and genotypic characterization of the antimicrobial resistance were conducted for 45 multidrug-resistant E. coli isolates from 208 samples of beef carcasses. The mechanisms of resistance were evaluated using polymerase chain reaction and sequencing methods, and the clonal relationship among isolates was evaluated using multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE)...
February 23, 2017: Microbial Drug Resistance: MDR: Mechanisms, Epidemiology, and Disease
keyword
keyword
117828
1
2
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"