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Low-intensity pulsed laser

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https://www.readbyqxmd.com/read/28438002/hot-luminescence-from-gold-nanoflowers-and-its-application-in-high-density-optical-data-storage
#1
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/28428549/low-noise-time-resolved-optical-sensing-of-electromagnetic-pulses-from-petawatt-laser-matter-interactions
#2
T S Robinson, F Consoli, S Giltrap, S J Eardley, G S Hicks, E J Ditter, O Ettlinger, N H Stuart, M Notley, R De Angelis, Z Najmudin, R A Smith
We report on the development and deployment of an optical diagnostic for single-shot measurement of the electric-field components of electromagnetic pulses from high-intensity laser-matter interactions in a high-noise environment. The electro-optic Pockels effect in KDP crystals was used to measure transient electric fields using a geometry easily modifiable for magnetic field detection via Faraday rotation. Using dielectric sensors and an optical fibre-based readout ensures minimal field perturbations compared to conductive probes and greatly limits unwanted electrical pickup between probe and recording system...
April 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28427634/enhanced-porosity-and-permeability-of-three-dimensional-alginate-scaffolds-via-acoustic-microstreaming-induced-by-low-intensity-pulsed-ultrasound
#3
Gepu Guo, Yong Ma, Yang Guo, Chunbing Zhang, Xiasheng Guo, Juan Tu, Alfred C H Yu, Junru Wu, Dong Zhang
The shear stress resulting from the microstreaming induced by low-intensity pulsed ultrasound (LIPUS) has been often used to improve the permeability of cell membrane or porous engineering scaffolds. In the present study, three-dimensional (3-D) scaffold culture systems were constituted to simulate the in vivo microenvironment, providing benefits for cell growth. In order to investigate the mechanism underlying the enhanced porosity and permeability of the 3-D alginate scaffolds by using LIPUS with varied acoustic intensities, two quantitative imaging techniques (i...
July 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28414231/organic-phosphorescence-nanowire-lasers
#4
Zhenyi Yu, Yishi Wu, Lu Xiao, Jianwei Chen, Qing Liao, Jiannian Yao, Hongbing Fu
Organic solid-state lasers (OSSLs) based on singlet fluorescence have merited intensive study as an important class of light sources. Although the use of triplet phosphors has led to 100% internal quantum efficiency in organic light-emitting diodes (OLEDs), stumbling blocks in triplet lasing include generally forbidden intersystem crossing (ISC) and a low quantum yield of phosphorescence (ΦP). Here, we reported the first triplet-phosphorescence OSSL from a nanowire microcavity of a sulfide-substituted difluoroboron compound...
April 25, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28383017/room-temperature-subnanosecond-waveguide-lasers-in-nd-yvo4-q-switched-by-phase-change-vo2-a-comparison-with-2d-materials
#5
Weijie Nie, Rang Li, Chen Cheng, Yanxue Chen, Qingming Lu, Carolina Romero, Javier R Vázquez de Aldana, Xiaotao Hao, Feng Chen
We report on room-temperature subnanosecond waveguide laser operation at 1064 nm in a Nd:YVO4 crystal waveguide through Q-switching of phase-change nanomaterial vanadium dioxide (VO2). The unique feature of VO2 nanomaterial from the insulating to metallic phases offers low-saturation-intensity nonlinear absorptions of light for subnanosecond pulse generation. The low-loss waveguide is fabricated by using the femtosecond laser writing with depressed cladding geometry. Under optical pump at 808 nm, efficient pulsed laser has been achieved in the Nd:YVO4 waveguide, reaching minimum pulse duration of 690 ps and maximum output average power of 66...
April 6, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28382317/probing-ultra-fast-processes-with-high-dynamic-range-at-4th-generation-light-sources-arrival-time-and-intensity-binning-at-unprecedented-repetition-rates
#6
S Kovalev, B Green, T Golz, S Maehrlein, N Stojanovic, A S Fisher, T Kampfrath, M Gensch
Understanding dynamics on ultrafast timescales enables unique and new insights into important processes in the materials and life sciences. In this respect, the fundamental pump-probe approach based on ultra-short photon pulses aims at the creation of stroboscopic movies. Performing such experiments at one of the many recently established accelerator-based 4th-generation light sources such as free-electron lasers or superradiant THz sources allows an enormous widening of the accessible parameter space for the excitation and/or probing light pulses...
March 2017: Structural Dynamics (Melville, N.Y.)
https://www.readbyqxmd.com/read/28338214/light-therapies-for-acne-abridged-cochrane-systematic-review-including-grade-assessments
#7
REVIEW
J Barbaric, R Abbott, P Posadzki, M Car, L H Gunn, A M Layton, A Majeed, J Car
We undertook a Cochrane review of randomized controlled trials (RCTs) evaluating the effects of light-based interventions for acne vulgaris. We searched the Cochrane Skin Specialised Register, CENTRAL, MEDLINE, Embase, LILACS, ISI Web of Science, and grey literature sources (September 2015). We used the Grading of Recommendations Assessment, Development and Evaluation Working Group approach to assess the quality of evidence (QE). We included 71 RCTs (4211 participants, median sample size 31). Results from a single study (n = 266, low QE) showed little or no difference in effectiveness on participants' assessment of improvement between 20% aminolevulinic acid (ALA) photodynamic therapy (PDT), activated by blue light, versus vehicle plus blue light, whereas another study (n = 180) of a comparison of ALA-PDT (red light) concentrations showed 20% ALA-PDT was no more effective than 15%, but better than 10% and 5% ALA-PDT...
March 24, 2017: British Journal of Dermatology
https://www.readbyqxmd.com/read/28317370/two-dimensional-ch3nh3pbi3-perovskite-nanosheets-for-ultrafast-pulsed-fiber-lasers
#8
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, Dingyuan 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 thicknesses of a few unit cells are more suitable for investigating the intrinsic nonlinear optical properties because bulk recombination of photocarriers and the nonlinear scattering are relatively small...
March 29, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28315815/self-assembled-photoadditives-in-polyester-films-allow-stop-and-go-chemical-release
#9
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→365nm LiYF4:Tm(3+), Yb(3+) upconverting nanoparticles (UCNP). Subsequently, neat ZnO and UCNP blended PLLA films of sub-50μm 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 50mW NIR irradiated PLLA/photoadditive film compared to non-irradiated PLLA control films...
March 16, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/28288450/laser-treatment-of-tattoos-basic-principles
#10
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
#11
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
#12
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
#13
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
#14
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
#15
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
#16
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
#17
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
#18
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
#19
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
#20
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
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