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Infrared light

M S Krivokorytov, Q Zeng, B V Lakatosh, A Yu Vinokhodov, Yu V Sidelnikov, V O Kompanets, V M Krivtsun, K N Koshelev, C D Ohl, V V Medvedev
Targeting micrometer sized metal droplets with near-infrared sub-picosecond laser pulses generates intense stress-confined acoustic waves within the droplet. Spherical focusing amplifies their pressures. The rarefaction wave nucleates cavitation at the center of the droplet, which explosively expands with a repeatable fragmentation scenario resulting into high-speed jetting. We predict the number of jets as a function of the laser energy by coupling the cavitation bubble dynamics with Rayleigh-Taylor instabilities...
January 12, 2018: Scientific Reports
Huaixiang Tian, Zhuoyan Lu, Danfeng Li, Jing Hu
Citral-loaded solid lipid nanoparticles (citral-SLNs) were prepared via a high-pressure homogenization method, using glyceryl monostearate (GMS) as the solid lipid and a mixture of Tween 80 (T-80) and Span 80 (S-80) at a weight ratio of 1:1 as the surfactant. The microstructure and properties of the citral-SLNs were characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA)...
May 15, 2018: Food Chemistry
Feng Wang, Hayk Harutyunyan
Plasmonic nanoantennas and metamaterials concentrate optical energy into nanometric volumes strongly enhancing the light-matter interaction. This makes them promising platforms for optical sensing, nonlinear effects and quantum optics. However, absorption losses and radiative damping result in broad, low quality factor (Q) resonances of plasmonic systems that significantly limit their performance. Here, we develop a hybrid plasmonic/dielectric metasurface that can simultaneously achieve high Q and large field enhancement values in the near infrared by forming a hybridized mode between the nanoantennas' plasmonic mode and the photonic waveguide mode of Si device layer...
January 8, 2018: Optics Express
Jeonghyun Huh, José Azaña
A fiber-optic system is proposed and experimentally demonstrated for real-time, on-the-fly identification of an incoherent-light energy spectrum pattern based on dispersion-induced time-spectrum convolution. In the proposed system, the incoming frequency-spectrum patterns to be identified are modulated by a time-mapped version of the target intensity profile. Following propagation through a suitable fiber-optic dispersive medium, the measured output temporal waveform provides a correlation of the incoming spectra with the programmed target pattern...
January 15, 2018: Optics Letters
Ramon A Martinez, Genevieve Plant, Kaiwen Guo, Brian Janiszewski, Michael J Freeman, Robert L Maynard, Mohammed N Islam, Fred L Terry, Oseas Alvarez, Francois Chenard, Robert Bedford, Ricky Gibson, Agustin I Ifarraguerri
We demonstrate an all-fiber supercontinuum source that generates a continuous spectrum from 1.6 μm to >11  μm with 417 mW on-time average power at 33% duty cycle. By utilizing a master oscillator power amplifier pump with three amplification stages and concatenating solid core ZBLAN, arsenic sulfide, and arsenic selenide fibers, we shift 1550 nm light to ∼4.5  μm, ∼6.5  μm, and >11  μm, respectively. With 69 mW past 7.5 μm, this source provides both high power and broad spectral expansion, while outputting a single fundamental mode...
January 15, 2018: Optics Letters
Saraswati Behera, Swagato Sarkar, Joby Joseph
In this Letter we report for the first time, to the best of our knowledge, a phase spatial light modulator (SLM)-based interference lithography (IL) approach for the realization of hexagonally packed helical photonic structures with a submicrometer scale spatial, as well as axial, periodicity over a large area. A phase-only SLM is used to electronically generate six phase-controlled plane beams. These six beams from the front side and a direct central backside beam are used together in an "inverted umbrella" geometry setup to realize the desired submicrometer axial periodic chiral photonic structures through IL...
January 1, 2018: Optics Letters
Mingyuan Zhou, Haiting Lin, S Susan Young, Jingyi Yu
The capability to track, detect, and identify human targets in highly cluttered scenes under extreme conditions, such as in complete darkness or on the battlefield, has been one of the primary tactical advantages in military operations. In this paper, we propose a new collaborative, multi-spectrum sensing method to achieve face detection and registration under low-light and unconstrained conditions. We design and prototype a novel type of hybrid sensor by combining a pair of near-infrared (NIR) cameras and a thermal camera (a long-wave infrared camera)...
January 1, 2018: Applied Optics
Yan Lv, Lin Yue, Qian Li, Baoyi Shao, Sen Zhao, Haitao Wang, Shijia Wu, Zhouping Wang
Herein, the design and synthesis of a multifunctional (Fe3O4-NaYF4:Yb,Tm)@TiO2 photocatalyst through a facile sol-gel process combined with electrostatic self-assembly has been reported. Particularly, as an upconversion sensor, NaYF4:Yb,Tm nanoparticles have the ability to convert near-infrared (NIR) light into ultraviolet (UV) emissions, so that the catalytic body TiO2 can indirectly utilize the NIR part of sunlight but not UV light. The excellent photocatalytic activity of the hybrid samples is evaluated using a model of the degradation of methylene blue (MB)...
January 12, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Yunxia Wang, Shengliang Li, Pengbo Zhang, Haotian Bai, Liheng Feng, Fengting Lv, Libing Liu, Shu Wang
Remote control and noninvasive manipulation of cellular bioprocess has received intensive attention as a powerful technology to control cell functions. Here, a strategy is developed to remotely control intracellular gene expression with high spatial and temporal resolutions by using photothermal-responsive conjugated polymer nanoparticles (CPNs) as the transducer under near-infrared light irradiation. After being modified with positive charged peptide, the CPNs with superior photothermal conversion capacity could effectively coat on the surface of living cells and generate localized heat to trigger target gene expression...
January 12, 2018: Advanced Materials
Pau Molet, Juan Luis Garcia-Pomar, Cristiano Matricardi, Miquel Garriga, Maria Isabel Alonso, Agustín Mihi
The design of ultrathin semiconducting materials that achieve broadband absorption is a long-sought-after goal of crucial importance for optoelectronic applications. To date, attempts to tackle this problem consisted either of the use of strong-but narrowband-or broader-but moderate-light-trapping mechanisms. Here, a strategy that achieves broadband optimal absorption in arbitrarily thin semiconductor materials for all energies above their bandgap is presented. This stems from the strong interplay between Brewster modes, sustained by judiciously nanostructured thin semiconductors on metal films, and photonic crystal modes...
January 12, 2018: Advanced Materials
Farzad Salehpour, Javad Mahmoudi, Farzin Kamari, Saeed Sadigh-Eteghad, Seyed Hossein Rasta, Michael R Hamblin
Brain photobiomodulation (PBM) therapy using red to near-infrared (NIR) light is an innovative treatment for a wide range of neurological and psychological conditions. Red/NIR light is able to stimulate complex IV of the mitochondrial respiratory chain (cytochrome c oxidase) and increase ATP synthesis. Moreover, light absorption by ion channels results in release of Ca2+ and leads to activation of transcription factors and gene expression. Brain PBM therapy enhances the metabolic capacity of neurons and stimulates anti-inflammatory, anti-apoptotic, and antioxidant responses, as well as neurogenesis and synaptogenesis...
January 11, 2018: Molecular Neurobiology
Guang-Yu Pan, Hao-Ran Jia, Ya-Xuan Zhu, Fu-Gen Wu
Developing biocompatible and photodegradable photothermal agents (PTAs) holds great promise for potential clinical applications in photothermal cancer therapy. Herein, a new PTA was innovatively constructed by conjugating the hydrophobic near-infrared (NIR) heptamethine cyanine molecule IR825-NH2 with a double hydrophilic block copolymer methoxypoly(ethylene glycol)5k-block-poly(l-aspartic acid sodium salt)10 (abbreviated as PEG-PLD) via amine-carboxyl reaction. The as-designed PEG-PLD(IR825) was amphiphilic and could self-assemble into polymeric nanomicelles in aqueous solutions...
January 12, 2018: Nanoscale
Paul Giraud, Bo Hou, Sangyeon Pak, Jung Inn Sohn, Stephen Morris, SeungNam Cha, Jong Min Kim
We demonstrate the fabrication of solution processed highly crystalline p-type PbS nanowires via the oriented attachment of nanoparticles. The analysis of single nanowire field effect transistor (FET) devices revealed a hole conduction behaviour with average mobilities greater than 30 cm2 V-1 s-1, which is an order of magnitude higher than that reported to date for p-type PbS colloidal nanowires. We have investigated the response of the FETs to near-infrared light excitation and show herein that the nanowires exhibited gate-dependent photo-conductivities, enabling us to tune the device performances...
January 11, 2018: Nanotechnology
Xuemei Hu, Felix Heide, Qionghai Dai, Gordon Wetzstein
Emerging sensor designs increasingly rely on novel color filter arrays (CFAs) to sample the incident spectrum in unconventional ways. In particular, capturing a near-infrared (NIR) channel along with conventional RGB color is an exciting new imaging modality. RGB+NIR sensing has broad applications in computational photography, such as low-light denoising, it has applications in computer vision, such as facial recognition and tracking, and it paves the way toward low-cost single-sensor RGB and depth imaging using structured illumination...
April 2018: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
Saravanan Govindaraju, Arunkumar Rengaraj, Roshini Arivazhagan, Yun-Suk Huh, Kyusik Yun
Curcumin-conjugated gold clusters (CUR-AuNCs) were synthesized using a "green" procedure and utilized as an anticancer and a bioimaging agent. Curcumin is a well-known anticancer agent, which forms a cluster when reacting with a gold precursor under mild alkali condition. A fluorescence spectroscopy analysis showed that the CUR-AuNCs emitted red fluorescence (650 nm) upon visible light (550) irradiation. Fourier transform infrared spectroscopy analysis confirmed the stretching and bending nature between the gold atoms and curcumin...
January 11, 2018: Bioconjugate Chemistry
Andrea Zangari, Davide Micheli, Roberta Galeazzi, Antonio Tozzi
Electromagnetic radiation, in the visible and infrared spectrum, is increasingly being investigated for its possible role in the most evolved brain capabilities. Beside experimental evidence of electromagnetic cellular interactions, the possibility of light propagation in the axon has been recently demonstrated using computational modelling, although an explanation of its source is still not completely understood. We studied electromagnetic radiation onset and propagation at optical frequencies in myelinated axons, under the assumption that ion channel currents in the node of Ranvier behave like an array of nanoantennas emitting in the wavelength range from 300 to 2500 nm...
January 11, 2018: Scientific Reports
Chaoyu Song, Feng-Ren Fan, Ningning Xuan, Shenyang Huang, Guowei Zhang, Chong Wang, Zhengzong Sun, Hua Wu, Hugen Yan
Due to the strong quantum confinement effect, few-layer γ-InSe exhibits a layer-dependent bandgap, spanning the visible and near infrared regions, and thus recently draws tremendous attention. As a two-dimensional material, the mechanical flexibility provides an additional tuning knob for the electronic structures. Here, for the first time, we engineer the band structures of few-layer and bulk-like InSe by uniaxial tensile strain, and observe salient shift of photoluminescence (PL) peaks. The shift rate of the optical gap is approximately 90-100 meV per 1% strain for 4- to 8-layer samples, which is much larger than that for the widely studied MoS2 monolayer...
January 11, 2018: ACS Applied Materials & Interfaces
Xiaoqin Shen, Rigoberto Castro Beltran, Vinh M Diep, Soheil Soltani, Andrea M Armani
Coherent frequency generators are an enabling platform in basic science and applied technology. Originally reliant on high-power lasers, recently comb generation has been demonstrated in ultrahigh-Q microcavities. The large circulating intensity within the cavity results in strong light-matter interaction, giving rise to Kerr parametric oscillations for comb generation. However, the comb generation threshold is limited by competing nonlinear effects within the cavity material and low intrinsic material Kerr coefficients...
January 2018: Science Advances
Tsung-Hsun Yang, Hsu-Yi Huang, Ching-Cherng Sun, Benoît Glorieux, Xuan-Hao Lee, Yeh-Wei Yu, Te-Yuan Chung
Phosphor-converted white light-emitting diodes (pc-WLEDs) have become a major light source in general lighting. To stabilize the photometric characteristics of pc-WLEDs, much effort has been made to manage the heat dissipation of the LED dies. The thermal problems of the phosphor parts, a critical reliability concern for pc-WLEDs, have recently attracted academic interest. This study proposed a practical approach for measuring phosphor temperature in an operating pc-WLED using a noncontact, instant detection method to remotely monitor the emission spectrum...
January 10, 2018: Scientific Reports
Belén Rubio Ruiz, Ana Perez-Lopez, Thomas Bray, Martin Lee, Alan Serrels, Martin Prieto, Manuel Arruebo, Neil O Carragher, Victor Sebastian, Asier Unciti-Broceta
Herein we report a straightforward method for the scalable preparation of Pd nanoparticles (Pd-NPs) with reduced inherent cytotoxicity and high photothermal conversion capacity. These Pd-NPs are rapidly taken up by cells and able to kill labelled cancer cells upon short exposure to near infrared (NIR) light. Following cell treatment with Pd-NPs, ablated areas were patterned with high precision by laser scanning microscopy, allowing to perform cell migration assays with unprecedented accuracy. Using coherent Raman microscopy, cells containing Pd-NPs were simultaneously ablated and imaged...
January 10, 2018: ACS Applied Materials & Interfaces
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