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Hyun-Hee Lee, Naru Kang, Inmyoung Park, Jungwook Park, Inyoung Kim, Jieun Kim, Namgyu Kim, Jae-Yun Lee, Young-Su Seo
Cordyceps militaris, a member of Ascomycota, a mushroom referred to as caterpillar Dong-chung-ha-cho, is commercially valuable because of its high content of bioactive substances including cordycepin and its potential for artificial cultivation. Cordycepin (3'-deoxyadenosine) is highly associated with the pharmacological effects of C. militaris. C. militaris is heterothallic in that two mating type loci, idiomorph MAT1-1 and MAT1-2, exist discretely in two different spores. In this study, nine C. militaris strains were mated with each other to prepare new strains that produced a larger amount of cordycepin than the parent strains...
April 25, 2017: Journal of Microbiology and Biotechnology
Feifei Xu, Fengzhou Fang, Yuanqing Zhu, Xiaodong Zhang
The material characteristics such as size effect are one of the most important factors that could not be neglected in cutting the material at nanoscale. The effects of anisotropic nature of single crystal materials in nano-cutting are investigated employing the molecular dynamics simulation. Results show that the size effect of the plastic deformation is based on different plastic carriers, such as the twin, stacking faults, and dislocations. The minimum uncut chip thickness is dependent on cutting direction, where even a negative value is obtained when the cutting direction is {110}<001>...
December 2017: Nanoscale Research Letters
Longshi Rao, Yong Tang, ZongTao Li, Xinrui Ding, Jiasheng Li, Shudong Yu, Caiman Yan, Hangaung Lu
White light produced by blue LEDs with yellow phosphor is the most widely used methods, but it results in poor quality in angular CCT uniformity. In this work, a novel technique was introduced to solve this problem by integrating different ZnO nanostructures into white light-emitting diodes. The experiment of ZnO doped films and the simulation of Finite-Difference Time-Domain (FDTD) were carried out. The result indicated scattering effect of ZnO nanoparticles could improve uniformity of scattering energy effectively...
April 17, 2017: Optics Express
Mingxia Song, Jean Dellinger, Olivier Demichel, Mickaël Buret, Gérard Colas Des Francs, Douguo Zhang, Erik Dujardin, Alexandre Bouhelier
Surface plasmon modes propagating in metal nanowires are conveniently excited by focusing a laser beam on one extremity of the nanowire. We find that the precise positioning of the nanowire inside the focal region drastically influences the excitation efficiency of the different SPP modes sustained by the plasmonic waveguide. We demonstrate a spatially selective excitation of bound and leaky surface plasmon modes with excitation maps that strongly depend on the orientation of the incident linear polarization...
April 17, 2017: Optics Express
Xiaoyu Weng, Luping Du, Peng Shi, Xiaocong Yuan
Optical cages attract considerable attentions recently owing to their potential applications in optical trapping, optical imaging and optical cloaking. However, the generation of tunable optical cage arrays in the transverse plane comes to a great challenge, which restricts the effectiveness of the above applications. In this work, we propose a full polarization-controlled method that optical cage arrays with tunable number and positions in the x-y plane can be generated by a so-called Dammann vector beam (DVB), both under the conditions of high- and low-NA focusing system...
April 17, 2017: Optics Express
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
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
Huaqing Qiu, Jianji Dong, Li Liu, Xinliang Zhang
We propose and experimentally demonstrate an energy-efficient optical diode based on the optomechanical effect. The optical signals could transmit during forward propagation while be blocked during backward propagation. When launching optical signal with a low power of 4.0 mW, the maximum resonance red-shift of the asymmetric silicon microring resonator (MRR) could be up to 0.74 nm, in this case, a forward-backward nonreciprocal transmission ratio (NTR) of 12.7 dB has been achieved. The 10-dB and 5-dB operation bandwidths are 0...
April 17, 2017: Optics Express
Zhaoyang Zhang, Danmeng Ma, Jun Liu, Yanyong Sun, Lin Cheng, Ghulam Abbas Khan, Yanpeng Zhang
By making use of the changes in optical properties such as absorption and dispersion around the resonance generated via electromagnetically induced transparency (EIT), we theoretically and experimentally investigate a "∞"-shape optical bistability (OB) versus frequency on the probe transmission with a Λ-shape EIT window in a rubidium atomic ensemble confined in a three-mirror optical ring cavity. Compared to the traditional OB reflected by a hysteresis loop versus power, such newly demonstrated optical bistable behavior (represented by a "∞"-shape non-overlapping region) by scanning probe and cavity detuning can experience dual bistabilities and be more sensitive to the change of experimental parameters...
April 17, 2017: Optics Express
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
Xian Zhou, Yutang Dai, Joseph Muna Karanja, Fufei Liu, Minghong Yang
Hydrogen gas sensing properties of Pt-WO<sub>3</sub> films on spiral microstructured fiber Bragg grating (FBG) has been demonstrated. Pt-WO<sub>3</sub> film was prepared by hydrothermal method. The spiral microsturctured FBG was fabricated using femtosecond laser. Spiral microstructure FBG hydrogen sensor can detect hydrogen concentration from 0.02% H<sub>2</sub> to 4% H<sub>2</sub> at room temperature, and the response time is shortened from a few minutes to 10~30 s...
April 17, 2017: Optics Express
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
Klaus Hueck, Niclas Luick, Lennart Sobirey, Jonas Siegl, Thomas Lompe, Henning Moritz, Logan W Clark, Cheng Chin
Absorption imaging of ultracold atoms is the foundation for quantitative extraction of information from experiments with ultracold atoms. Due to the limited exposure time available in these systems, the signal-to-noise ratio is largest for high intensity absorption imaging where the intensity of the imaging light is on the order of the saturation intensity. In this case, the absolute value of the intensity of the imaging light enters as an additional parameter making it more sensitive to systematic errors. Here, we present a novel and robust technique to determine the imaging beam intensity in units of the effective saturation intensity to better than 5%...
April 17, 2017: Optics Express
Janaka C Ranasinghesagara, Giuseppe De Vito, Vincenzo Piazza, Eric O Potma, Vasan Venugopalan
We develop a computational framework to examine the factors responsible for scattering-induced distortions of coherent anti-Stokes Raman scattering (CARS) signals in turbid samples. We apply the Huygens-Fresnel wave-based electric field superposition (HF-WEFS) method combined with the radiating dipole approximation to compute the effects of scattering-induced distortions of focal excitation fields on the far-field CARS signal. We analyze the effect of spherical scatterers, placed in the vicinity of the focal volume, on the CARS signal emitted by different objects (2μm diameter solid sphere, 2μm diameter myelin cylinder and 2μm diameter myelin tube)...
April 17, 2017: Optics Express
Jie You, Nicolae C Panoiu
A computational approach to evaluate the bit-error ratio (BER) in silicon photonic systems employing high-order phase-shift keying (PSK) modulation formats is presented. Specifically, the investigated systems contain a silicon based optical interconnect, namely a strip silicon photonic waveguide or a silicon photonic crystal waveguide, and direct-detection receivers suitable to detect PSK and amplitude-shaped PSK signals. The superposition of a PSK signal and complex additive white Gaussian noise passes through the optical interconnect and subsequently through two detection-branch receivers...
April 17, 2017: Optics Express
Andriy Shevchenko, Markus Nyman, Ville Kivijärvi, Matti Kaivola
Spatial dispersion is an intriguing property of essentially all nanostructured optical media. In particular, it makes optical waves with equal frequencies and polarizations have different wavelengths, if they propagate in different directions. This can offer new approaches to control light radiation and propagation. Spatially dispersive nanomaterials, such as metamaterials, are often treated in terms of wave parameters, such as refractive index and impedance retrieved from reflection and transmission coefficients of the material at each incidence angle...
April 17, 2017: Optics Express
Martin Pekař, Jeannet van Rens, Martin B van der Mark
Smart minimally invasive devices face a connectivity challenge. An example is found in intracardiac echocardiography where the signal transmission and supply of power at the distal end require many thin and fragile wires in order to keep the catheter slim and flexible. We have built a fully functional bench-top prototype to demonstrate that electrical wires may be replaced by optical fibers. The prototype is immediately scalable to catheter dimensions. The absence of conductors will provide intrinsic galvanic isolation as well as radio frequency (RF) and magnetic resonance imaging (MRI) compatibility...
April 17, 2017: Optics Express
Jia Liu, Xianqiang He, Jiahang Liu, Yan Bai, Difeng Wang, Tieqiao Chen, Yihao Wang, Feng Zhu
Absorption and scattering by molecules, aerosols and hydrosols, and the reflection and transmission over the sea surface can modify the original polarization state of sunlight. However, water-leaving radiance polarization, containing embedded water constituent information, has largely been neglected. Here, the efficiency of the parallel polarization radiance (PPR) for enhancing ocean color signal of suspended particulate matter is examined via vector radiative transfer simulations and laboratory experiments...
April 17, 2017: Optics Express
Peng-Wang Zhai, Yongxiang Hu, David M Winker, Bryan A Franz, Jeremy Werdell, Emmanuel Boss
Inelastic scattering plays an important role in ocean optics. The main inelastic scattering mechanisms include Raman scattering, fluorescence by colored dissolved organic matter (FDOM), and fluorescence by chlorophyll. This paper reports an implementation of all three inelastic scattering mechanisms in the exact vector radiative transfer model for coupled atmosphere and ocean Systems (CAOS). Simulation shows that FDOM contributes to the water radiation field in the broad visible spectral region, while chlorophyll fluorescence is limited in a narrow band centered at 685 nm...
April 17, 2017: Optics Express
Yi Zhao, Ceji Fu
In this paper, we present a one-dimensional periodic microstructure for multiband selective absorbers of thermal radiation. The microstructure is made of Ag/SiO<sub>2</sub>/Ag core/shell coaxial cylinders horizontally lying on top of a SiO<sub>2</sub> dielectric spacer and an opaque silver substrate. The spectral-directional absorptivity of the proposed structure was numerically investigated with the finite element based Comsol Multiphysics software. Multiband selective absorption in the wavenumber range from 2500 to 20000 cm<sup>-1</sup> for TM-wave incidence was obtained...
April 17, 2017: Optics Express
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