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Low-intensity pulsed laser

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https://www.readbyqxmd.com/read/28220602/mexametric-and-cutometric-assessment-of-the-signs-of-aging-of-the-skin-area-around-the-eyes-after-the-use-of-non-ablative-fractional-laser-non-ablative-radiofrequency-and-intense-pulsed-light
#1
Anna Maria Kołodziejczak, Helena Rotsztejn
The assessment of the signs of aging within eyes area in cutometric (skin elasticity) and mexametric (discoloration and severity of erythema) examination after the treatment with: non-ablative fractional laser, non-ablative radiofrequency (RF) and intense light source (IPL). This study included 71 patients, aged 33-63 years (the average age was 45.81) with Fitzpatrick skin type II and III. 24 patients received 5 successive treatment sessions with a 1,410-nm non-ablative fractional laser in two-week intervals, 23 patients received 5 successive treatment sessions with a non-ablative RF in one-week intervals and 24 patients received 5 successive treatment sessions with an IPL in two-week intervals...
February 21, 2017: Dermatologic Therapy
https://www.readbyqxmd.com/read/28158105/time-resolved-thermal-lens-spectroscopy-with-a-single-pulsed-laser-excitation-beam-an-analytical-model-for-dual-beam-mode-mismatched-experiments
#2
Mohammad Sabaeian, Hamidreza Rezaei, Abdolmohammad Ghalambor-Dezfouli
Pulsed laser beam excitations are more commonly used in thermal lens spectroscopy (TLS) than continuous-wave (CW) ones, because CW excitations limit the measurement to linear absorption processes [J. Opt. A5, 256 (2003)]. In this work, we present a new and full analytical model for a single-pulsed laser excitation dual-beam mode-mismatched TLS for low absorption solid-state and liquid samples. Our model has been based on a new solution of time-dependent heat equation for a finite-radius cylindrical sample exposed to a single-pulsed excitation laser beam...
February 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28157952/intensity-fluctuation-of-a-gain-switched-semiconductor-laser-for-quantum-key-distribution-systems
#3
Kensuke Nakata, Akihisa Tomita, Mikio Fujiwara, Ken-Ichiro Yoshino, Akio Tajima, Atsushi Okamoto, Kazuhisa Ogawa
Security certification of quantum key distribution (QKD) systems under practical conditions is necessary for social deployment. This article focused on the transmitter, and, in particular, investigated the intensity fluctuation of the optical pulses emitted by a gain-switched semiconductor laser used in QKD systems implementing decoy-BB84 protocol. A large intensity fluctuation was observed for low excitation, showing strong negative correlation between the adjacent pulses, which would affect the final key rate...
January 23, 2017: Optics Express
https://www.readbyqxmd.com/read/28146539/laser-crater-enhanced-raman-spectroscopy
#4
Vasily N Lednev, Pavel A Sdvizhenskii, Mikhail Ya Grishin, Mikhail N Filippov, Alexander N Shchegolikhin, Sergey M Pershin
Raman signal enhancement by multiple scattering inside laser crater cones was observed for the first time, to the best of our knowledge. Laser crater enhanced Raman spectroscopy (LCERS) yielded a 14-fold increase in the Raman spectra bands due to efficient multiple scattering of laser irradiation within the laser crater walls. The same pulsed Nd:YAG laser (532 nm, 10 ns) was used for both laser crater formation and Raman scattering experiments by varying the output pulse energy. First, powerful pulses are used to produce the laser crater; then low-energy pulses are used to perform Raman scattering measurements...
February 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/28135747/-flexible-guidance-of-ultra-short-laser-pulses-in-ophthalmic-therapy-systems
#5
J Blum, M Blum, M S Rill, J Haueisen
In the last 20 years, the role of ultrashort pulsed lasers in ophthalmology has become increasingly important. However, it is still impossible to guide ultra-short laser pulses with standard glass fibres. The highly energetic femtosecond pulses would destroy the fibre material, and non-linear dispersion effects would significantly change beam parameters. In contrast, photonic crystal fibres mainly guide the laser pulses in air, so that absorption and dispersive pulse broadening have essentially no effect. This article compares classical beam guidance with mirrors, lenses and prisms with photonic crystal fibres and describes the underlying concepts and the current state of technology...
January 2017: Klinische Monatsblätter Für Augenheilkunde
https://www.readbyqxmd.com/read/28125779/monolayer-ws2-nanopores-for-dna-translocation-with-light-adjustable-sizes
#6
Gopinath Danda, Paul Masih Das, Yung-Chien Chou, Jerome T Mlack, William M Parkin, Carl H Naylor, Kazunori Fujisawa, Tianyi Zhang, Laura Beth Fulton, Mauricio Terrones, Alan T Charlie Johnson, Marija Drndić
Two-dimensional materials are promising for a range of applications, as well as testbeds for probing the physics of low-dimensional systems. Tungsten disulfide (WS2) monolayers exhibit a direct band gap and strong photoluminescence (PL) in the visible range, opening possibilities for advanced optoelectronic applications. Here, we report the realization of two-dimensional nanometer-size pores in suspended monolayer WS2 membranes, allowing for electrical and optical response in ionic current measurements. A focused electron beam was used to fabricate nanopores in WS2 membranes suspended on silicon-based chips and characterized using PL spectroscopy and aberration-corrected high-resolution scanning transmission electron microscopy...
February 1, 2017: ACS Nano
https://www.readbyqxmd.com/read/28107035/determination-of-the-zinc-concentration-in-human-fingernails-using-laser-induced-breakdown-spectroscopy
#7
Vlora A Riberdy, Christopher J Frederickson, Steven J Rehse
The absolute concentration of Zn in human fingernail clippings was determined ex vivo using 1064 nm laser-induced breakdown spectroscopy and confirmed by speciated isotope dilution mass spectrometry. A nail testing protocol that sampled across the nail (perpendicular to the direction of growth) was developed and validated by scanning electron microscopy energy-dispersive X-ray spectrometry. Using this protocol, a partial least squares (PLS) regression model predicted the Zn concentration in the fingernails of five people to within an average of 7 ppm...
January 1, 2017: Applied Spectroscopy
https://www.readbyqxmd.com/read/28106472/sample-preparation-for-repeated-measurements-on-a-single-liquid-droplet-using-laser-induced-breakdown-spectroscopy
#8
Violeta Lazic, Roberta Fantoni, Antonio Palucci, Massimiliano Ciaffi
We studied changes in laser-induced breakdown spectroscopy (LIBS) signal intensity with the thickness of a liquid layer placed on a solid substrate, where an easily evaporating methanol sample was used. For a certain optimal liquid film thickness we obtained a manifold increase of the LIBS signal from methanol. Progressive liquid film thinning leads to a reduction and a successive disappearance of laser-induced splashes; the latter condition drastically reduces the sample consumption and allows measurements to be repeated many times on a single liquid droplet...
January 1, 2017: Applied Spectroscopy
https://www.readbyqxmd.com/read/27965517/laser-enhanced-high-intensity-focused-ultrasound-heating-in-an-in-vivo-small-animal-model
#9
Janggun Jo, Xinmai Yang
The enhanced heating effect during the combination of high-intensity focused ultrasound (HIFU) and low-optical-fluence laser illumination was investigated by using an in vivo murine animal model. The thighs of murine animals were synergistically irradiated by HIFU and pulsed nano-second laser light. The temperature increases in the target region were measured by a thermocouple under different HIFU pressures, which were 6.2, 7.9, and 9.8 MPa, in combination with 20 mJ/cm(2) laser exposures at 532 nm wavelength...
November 21, 2016: Applied Physics Letters
https://www.readbyqxmd.com/read/27958518/-mw-peak-power-at-266-nm-low-jitter-khz-repetition-rate-from-intense-pumped-microlaser
#10
Lihe Zheng, Arvydas Kausas, Takunori Taira
Intense pulse pumped microlaser is proposed for high peak power and low timing jitter at high repetition rate. It is based on Intense and Fast Pulse Pump (IFPP) technique, in which fast pulse pumps up the upper-level population and then dumps it rapidly by Q-switching. That could come close to complete pumping efficiency to reduce thermal problems and contribute to suppress the timing jitter of passively Q-switched laser. In this work, linearly polarized 1064 nm beam from [100]-cut YAG/Nd3+:YAG and [110]-cut Cr4+:YAG passively Q-switched microlaser is directly guided into nonlinear crystals to obtain 532 nm and 266 nm output...
December 12, 2016: Optics Express
https://www.readbyqxmd.com/read/27939089/the-resolve-trial-for-people-with-chronic-low-back-pain-protocol-for-a-randomised-clinical-trial
#11
Matthew K Bagg, Markus Hübscher, Martin Rabey, Benedict M Wand, Edel O'Hagan, G Lorimer Moseley, Tasha R Stanton, Chris G Maher, Stephen Goodall, Sopany Saing, Neil E O'Connell, Hannu Luomajoki, James H McAuley
INTRODUCTION: Low back pain is the leading worldwide cause of disability, and results in significant personal hardship. Most available treatments, when tested in high-quality randomised, controlled trials, achieve only modest improvements in pain, at best. Recently, treatments that target central nervous system function have been developed and tested in small studies. Combining treatments that target central nervous system function with traditional treatments directed towards functioning of the back is a promising approach that has yet to be tested in adequately powered, prospectively registered, clinical trials...
January 2017: Journal of Physiotherapy
https://www.readbyqxmd.com/read/27929036/optimal-generation-of-spatially-coherent-soft-x-ray-isolated-attosecond-pulses-in-a-gas-filled-waveguide-using-two-color-synthesized-laser-pulses
#12
Cheng Jin, Kyung-Han Hong, C D Lin
We numerically demonstrate the generation of intense, low-divergence soft X-ray isolated attosecond pulses in a gas-filled hollow waveguide using synthesized few-cycle two-color laser waveforms. The waveform is a superposition of a fundamental and its second harmonic optimized such that highest harmonic yields are emitted from each atom. We then optimize the gas pressure and the length and radius of the waveguide such that bright coherent high-order harmonics with angular divergence smaller than 1 mrad are generated, for photon energy from the extreme ultraviolet to soft X-rays...
December 8, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27918005/a-review-of-melasma-treatment-focusing-on-laser-and-light-devices
#13
Janet Y Li, Elizabeth Rc Geddes, Deanne M Robinson, Paul M Friedman
Melasma is a pigmentary disorder of unclear etiology with numerous treatment options and high recurrence rates. Laser and light therapies may be utilized cautiously as second- or third-line options for recalcitrant melasma, but low-energy settings are preferred due to the risk of postinflammatory hyperpigmentation and melasma stimulation. Commonly used lasers include the low-fluence 1064-nm Q-switched neodymium-doped yttrium aluminum garnet laser, nonablative fractionated lasers, and intense pulsed light. Strict sun protection, concomitant use of bleaching agents, and maintenance treatments are necessary...
December 2016: Seminars in Cutaneous Medicine and Surgery
https://www.readbyqxmd.com/read/27886497/large-cross-phase-modulations-at-the-few-photon-level
#14
Zi-Yu Liu, Yi-Hsin Chen, Yen-Chun Chen, Hsiang-Yu Lo, Pin-Ju Tsai, Ite A Yu, Ying-Cheng Chen, Yong-Fan Chen
We demonstrate an efficient cross-phase modulation (XPM) based on a closed-loop double-Λ system. The property of the double-Λ medium can be controlled by changing the phases of the applied optical fields. This phase-dependent XPM scheme can achieve large phase modulations at low-light intensities without requiring cavities or tightly focusing laser beams. With this scheme, we observe a π-level phase shift with two pulses, both consisting of eight photons in cold rubidium atoms. Such a novel scheme provides a simple route to generate strong interactions between photons and may have potential applications in all-optical quantum signal processing...
November 11, 2016: Physical Review Letters
https://www.readbyqxmd.com/read/27868127/digital-dna-detection-based-on-a-compact-optofluidic-laser-with-ultra-low-sample-consumption
#15
Wonsuk Lee, Qiushu Chen, Xudong Fan, Dong Ki Yoon
DNA lasers self-amplify optical signals from a DNA analyte as well as thermodynamic differences between sequences, allowing quasi-digital DNA detection. However, these systems have drawbacks, such as relatively large sample consumption and complicated dye labelling. Moreover, although the lasing signal can detect the target DNA, it is superimposed on an unintended fluorescence background, which persists for non-target DNA samples as well. From an optical point of view, it is thus not truly digital detection and requires spectral analysis to identify the target...
November 29, 2016: Lab on a Chip
https://www.readbyqxmd.com/read/27828039/implementation-of-a-svwp-based-laser-beam-shaping-technique-for-generation-of-100-mj-level-picosecond-pulses
#16
J Adamonis, A Aleknavičius, K Michailovas, S Balickas, V Petrauskienė, T Gertus, A Michailovas
We present implementation of the energy-efficient and flexible laser beam shaping technique in a high-power and high-energy laser amplifier system. The beam shaping is based on a spatially variable wave plate (SVWP) fabricated by femtosecond laser nanostructuring of glass. We reshaped the initially Gaussian beam into a super-Gaussian (SG) of the 12th order with efficiency of about 50%. The 12th order of the SG beam provided the best compromise between large fill factor, low diffraction on the edges of the active media, and moderate intensity distribution modification during free-space propagation...
October 1, 2016: Applied Optics
https://www.readbyqxmd.com/read/27827347/imaging-pulsed-laser-deposition-growth-of-homo-epitaxial-srtio3-by-low-energy-electron-microscopy
#17
A J H van der Torren, S J van der Molen, J Aarts
By combining low-energy electron microscopy with in situ pulsed laser deposition we have developed a new technique for film growth analysis, making use of both diffraction and real-space information. Working at the growth temperature, we can use: the intensity and profile variations of the specular beam to follow the coverage in a layer-by-layer fashion; real-space microscopy to follow e.g. atomic steps at the surface; and electron reflectivity to probe the unoccupied band structure of the grown material. Here, we demonstrate our methodology for homo-epitaxial growth of SrTiO3...
November 9, 2016: Nanotechnology
https://www.readbyqxmd.com/read/27805636/ultra-stable-high-average-power-femtosecond-laser-system-tunable-from-1-33-to-20%C3%A2-%C3%A2-%C3%AE-m
#18
Tobias Steinle, Florian Mörz, Andy Steinmann, Harald Giessen
A highly stable 350 fs laser system with a gap-free tunability from 1.33 to 2.0 μm and 2.13 to 20 μm is demonstrated. Nanojoule-level pulse energy is achieved in the mid-infrared at a 43 MHz repetition rate. The system utilizes a post-amplified fiber-feedback optical parametric oscillator followed by difference frequency generation between the signal and idler. No locking or synchronization electronics are required to achieve outstanding free-running output power and spectral stability of the whole system...
November 1, 2016: Optics Letters
https://www.readbyqxmd.com/read/27802717/high-performance-charge-state-resolving-ion-energy-analyzer-optimized-for-intense-laser-studies-on-low-density-cluster-targets
#19
D Komar, K-H Meiwes-Broer, J Tiggesbäumker
We report on a versatile ion analyzer which is capable to resolve ion charge states and energies with a resolution of E/ΔE = 100 at 75 keV/nucleon. Charge states are identified by their characteristic deflection in a magnetic field, whereas the ion energies are independently determined by a time-of-flight measurement. To monitor the signals a delay-line detector is used which records ion impact positions and times in each laser shot. Compared to conventional Thomson parabola spectrometers our instrument provides a low background measurement, hence a superior dynamic range...
October 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27749891/gigahertz-repetition-rate-tm-doped-fiber-laser-passively-mode-locked-by-optoacoustic-effects-in-nanobore-photonic-crystal-fiber
#20
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
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