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Low-intensity pulsed laser

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https://www.readbyqxmd.com/read/28317370/two-dimensional-ch3nh3pbi3-perovskite-nanosheets-for-ultrafast-pulsed-fiber-lasers
#1
Pengfei Li, Yao Chen, Tieshan Yang, Ziyu Wang, Han Lin, Yanhua Xu, Lei Li, Haoran Mu, Bannur Nanjunda Shivananju, Yupeng Zhang, Qinglin Zhang, Anlian Pan, Shaojuan Li, Ding Yuan Tang, Baohua Jia, Han Zhang, Qiaoliang Bao
Even though the nonlinear optical effects of solution processed organic-inorganic perovskite films have been studied, the nonlinear optical properties in two-dimensional (2D) perovskites especially their applications for ultrafast photonics are largely unexplored. In comparison to bulk perovskite films, 2D perovskite nanosheets with small thickness of a few unit cells are more suitable for investigating the intrinsic nonlinear optical properties because bulk recombination of photo-carriers and the nonlinear scattering are relatively small...
March 20, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28315815/self-assembled-photoadditives-in-polyester-films-allow-stop-and-go-chemical-release
#2
Ting Cheng, Richard O'Rorke, Raphael Francois Ortiz, Tay Yee Yan, Eva Hemmer, Fiorenzo Vetrone, Robert S Marks, Terry W J Steele
Near-infrared (NIR) triggered chemical delivery allows on-demand release with the advantage of external tissue stimulation. Bioresorbable polyester poly-L-lactic acid (PLLA) was compounded with photoadditives of neat zinc oxide (ZnO) nanoparticles and 980 → 365 nm LiYF4:Tm(3+), Yb(3+) upconverting nanoparticles (UCNP). Subsequently, neat ZnO and UCNP blended PLLA films of sub-50 μm thickness were knife casted with a hydrophobic small molecule drug mimic, fluorescein diacetate. The PLLA films displayed a 500 times increase in fluorescein diacetate release from the 50 mW NIR irradiated PLLA/photoadditive film compared to non-irradiated PLLA control films...
March 15, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/28288450/laser-treatment-of-tattoos-basic-principles
#3
Wolfgang Bäumler
Tattooing has become very popular worldwide during the past decades, and millions of people have one or many tattoos at different anatomical sites. The color of tattoos is mainly black, followed by red, green, blue, and other colors. A part of the tattooed people regret tattooing or have permanent problems with tattoos and therefore seek for tattoo removal. Tattoos consist of solid pigment particles in the skin. Thus, tattoo removal requires fragmentation of these permanently incorporated particles. The gold standard of tattoo removal is laser therapy...
2017: Current Problems in Dermatology
https://www.readbyqxmd.com/read/28279642/low-intensity-400%C3%A2-mw-cm-2-500%C3%A2-khz-pulsed-transcranial-ultrasound-preconditioning-may-mitigate-focal-cerebral-ischemia-in-rats
#4
Hangdao Li, Junfeng Sun, Daqu Zhang, Daryl Omire-Mayor, Peter A Lewin, Shanbao Tong
BACKGROUND: Preconditioning methods, which could increase tolerance of brain to subsequent ischemic injuries with a small dose of non-injury stimuli, have gained attention. Capitalizing on noninvasiveness and safety of ultrasound modality, the pulsed transcranial ultrasound stimulation (pTUS) approach may provide a novel treatment for patients with high risk of stroke. OBJECTIVE: This study's goal was to investigate whether the risk of stroke could be minimized or eliminated by prior exposure to low-intensity, pulsed transcranial ultrasound stimulation (pTUS)...
February 27, 2017: Brain Stimulation
https://www.readbyqxmd.com/read/28271006/vcsel-based-swept-source-for-low-cost-optical-coherence-tomography
#5
Sucbei Moon, Eun Seo Choi
We present a novel wavelength-swept laser source for optical coherence tomography (OCT) which is based on the conventional laser diode technology of the vertical-cavity surface-emitting laser (VCSEL). In our self-heating sweep VCSEL (SS-VCSEL), a VCSEL device is simply driven by ramped pulses of currents in direct intensity modulation. The intrinsic property of VCSEL produces a frequency-swept output through the self-heating effect. By the injected current, the temperature of the active region is gradually increased in this effect...
February 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28267751/cost-effectiveness-of-adjunct-non-pharmacological-interventions-for-osteoarthritis-of-the-knee
#6
Beth Woods, Andrea Manca, Helen Weatherly, Pedro Saramago, Eleftherios Sideris, Christina Giannopoulou, Stephen Rice, Mark Corbett, Andrew Vickers, Matthew Bowes, Hugh MacPherson, Mark Sculpher
BACKGROUND: There is limited information on the costs and benefits of alternative adjunct non-pharmacological treatments for knee osteoarthritis and little guidance on which should be prioritised for commissioning within the NHS. This study estimates the costs and benefits of acupuncture, braces, heat treatment, insoles, interferential therapy, laser/light therapy, manual therapy, neuromuscular electrical stimulation, pulsed electrical stimulation, pulsed electromagnetic fields, static magnets and transcutaneous electrical nerve Stimulation (TENS), based on all relevant data, to facilitate a more complete assessment of value...
2017: PloS One
https://www.readbyqxmd.com/read/28256507/high-operating-temperature-and-low-power-consumption-boron-nitride-nanosheets-based-broadband-uv-photodetector
#7
Manuel Rivera, Rafael Velázquez, Ali Aldalbahi, Andrew F Zhou, Peter Feng
We extend our work on the use of digitally controlled pulsed laser plasma deposition (PLPD) technique to synthesize high quality, 2-dimensional single crystalline boron nitride nanosheets (BNNSs) at a low substrate temperature for applications in high-performance deep UV photodetectors. The obtained sample consists of a large amount of BNNSs partially overlapping one another with random orientations. Each sheet is composed of a few (from 2 to 10) stacked atomic layers exhibiting high transparency due to its highly ordered hBN crystallinity...
March 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28248324/100%C3%A2-%C3%A2-khz-yb-fiber-laser-pumped-3%C3%A2-%C3%A2-%C3%AE-m-optical-parametric-amplifier-for-probing-solid-state-systems-in-the-strong-field-regime
#8
Giedre Marija Archipovaite, Stéphane Petit, Jean-Christophe Delagnes, Eric Cormier
We report on a laser source operating at 100 kHz repetition rate and delivering 8 μJ few-cycle mid-IR pulses at 3 μm. The system is based on optical parametric amplification pumped by a high repetition rate Yb-doped femtosecond fiber-chirped amplifier. This high-intensity ultrafast system is a promising tool for strong-field experiments (up to 50 GV/m and 186 T) in low ionization potential atomic and molecular systems, or solid-state physics with coincidence measurements. As a proof of principle, up to the sixth harmonic has been generated in a 1 mm zinc selenide sample...
March 1, 2017: Optics Letters
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
#9
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
#10
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
#11
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
#12
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
#13
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
#14
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 28, 2017: ACS Nano
https://www.readbyqxmd.com/read/28107035/determination-of-the-zinc-concentration-in-human-fingernails-using-laser-induced-breakdown-spectroscopy
#15
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
#16
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
#17
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
#18
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
#19
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
#20
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
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