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Sung Yong Jang, Jaeyoung Heo, Mi Ri Park, Min-Ho Song, Jong Nam Kim, Sung Ho Jo, Do-Youn Jeong, Hak Kyo Lee, Younghoon Kim, Sangnam Oh
Lactobacillus fermentum strain JDFM216, isolated from a Korean infant feces, possesses an enhancement of longevity and immune response on Caenorhabditis elegans host. To explore the molecular characteristics of strain JDFM216, we performed a whole-genome sequencing using PacBio system. The single circular DNA chromosome of 2,076,427 bp was completely assembled and 2,623 encoding sequences were predicted. Phylogenetically featured five genes possibly related to longevity and immune response of host were identified in L...
April 25, 2017: Journal of Microbiology and Biotechnology
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
L Rapp, R Meyer, L Furfaro, C Billet, R Giust, F Courvoisier
We develop a novel concept for ultra-high speed cleaving of crystalline materials with femtosecond lasers. Using Bessel beams in single shot, fracture planes can be induced nearly all along the Bessel zone in sapphire. For the first time, we show that only for a pulse duration below 650 fs, a single fracture can be induced in sapphire, while above this duration, cracks appear in all crystallographic orientations. We determine the influential parameters which are polarization direction, crystallographic axes and scanning direction...
April 17, 2017: Optics Express
Qingbin Fan, Daopeng Wang, Pengcheng Huo, Zijie Zhang, Yuzhang Liang, Ting Xu
Conventional method to generate autofocusing Airy (AFA) beam involves the optical Fourier transform (FT) system, which has a fairly long working distance due to the focal length of FT lens, presence of spatial light modulator (SLM) and auxiliary total reflection mirrors. Here, we propose an extremely compact design to generate high-efficiency AFA beam at visible frequency by using metasurface which is composed of a single layer array of amorphous titanium dioxide (TiO<sub>2</sub>) elliptical nanofins sitting on the fused-silica substrate...
April 17, 2017: Optics Express
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
Chao Jin, Liang Wang, Yuli Chen, Nan Guo, Wenghong Chung, Hoyin Au, Zhaohui Li, Hwa-Yaw Tam, Chao Lu
A single-measurement sweep-free distributed Brillouin optical time domain analyzer (BOTDA) sensor based on phase detection is proposed and experimentally demonstrated employing digital optical frequency comb (DOFC) probe signal. Brillouin Phase Spectrum (BPS) of DOFC probe induced by Brillouin interaction is measured using coherent detection in a single acquisition, without any frequency scanning and data averaging. Single-measurement BOTDA sensor based on BPS in 10km long fiber is demonstrated with a response time of 100 μs, which is limited only by the fiber length...
April 17, 2017: Optics Express
Jingkun Guo, Richard A Norte, S Gröblacher
Mechanical oscillators are at the heart of many sensor applications. Recently several groups have developed oscillators that are probed optically, fabricated from high-stress silicon nitride films. They exhibit outstanding force sensitivities of a few aN/Hz<sup>1/2</sup> and can also be made highly reflective, for efficient detection. The optical read-out usually requires complex experimental setups, including positioning stages and bulky cavities, making them impractical for real applications. In this paper we propose a novel way of building fully integrated all-optical force sensors based on low-loss silicon nitride mechanical resonators with a photonic crystal reflector...
April 17, 2017: Optics Express
F Mariani, F de León-Pérez, K J A Vendel, L Martín-Moreno, M P Van Exter
We present the first angle resolved measurements of extraordinary optical transmission (EOT) through hole array gratings in a gold film. Varying the lattice spacing of the arrays and looking at higher diffraction orders, we retrieve the angular emission pattern of the constituent holes with better signal to noise ratio than with single-hole experiments. We present a method to determine separately the angular dependence of the direct and resonant contribution to EOT by using the spectral features of the diffraction orders together with an established model...
April 17, 2017: Optics Express
Aliou Ly, Christophe Siour, Fabien Bretenaker
We built a 1-watt cw singly resonant optical parametric oscillator operating at an idler wavelength of 1.65 µm for application to quantum interfaces. The non resonant idler is frequency stabilized by side-fringe locking on a relatively high-finesse Fabry-Perot cavity, and the influence of intensity noise is carefully analyzed. A relative linewidth down to the sub-kHz level (about 30 Hz over 2 s) is achieved. A very good long term stability is obtained for both frequency and intensity.
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
Helen D Ford, Ralph P Tatam
Duct-profiling in test samples up to 25 mm in diameter has been demonstrated using a passive, low-coherence probe head with a depth resolution of 7.8 μm, incorporating an optical-fibre-linked conical mirror addressed by a custom-built array of single-mode fibres. Zemax modelling, and experimental assessment of instrument performance, show that degradation of focus, resulting from astigmatism introduced by the conical mirror, is mitigated by the introduction of a novel lens element. This enables a good beam focus to be achieved at distances of tens of millimetres from the cone axis, not achievable when the cone is used alone...
April 17, 2017: Optics Express
Chen Wei, Hongyu Luo, Hongxia Shi, YanJia Lyu, Han Zhang, Yong Liu
In this paper, we demonstrate a wavelength widely tunable gain-switched Er<sup>3+</sup>-doped ZBLAN fiber laser around 2.8 μm. The laser can be tuned over 170 nm (2699 nm~2869.9 nm) for various pump power levels, while maintaining stable μs-level single-pulse gain-switched operation with controllable output pulse duration at a selectable repetition rate. To the best of our knowledge, this is the first wavelength tunable gain-switched fiber laser in the 3 μm spectral region with the broadest tuning range (doubling the record tuning range) of the pulsed fiber lasers around 3 μm...
April 17, 2017: Optics Express
Pablo D Ruiz, Jonathan M Huntley
We describe a single-shot technique to measure areal profiles on optically smooth and stepped surfaces for applications where rapid data acquisition in non-cooperative environments is essential. It is based on hyperspectral interferometry (HSI), a technique in which the output of a white-light interferometer provides the input to a hyperspectral imaging system. Previous HSI implementations suffered from inefficient utilisation of the available pixels which limited the number of measured coordinates and/or unambiguous depth range...
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
Simone Ferrari, Vadim Kovalyuk, Wladislaw Hartmann, Andreas Vetter, Oliver Kahl, Changhyoup Lee, Alexander Korneev, Carsten Rockstuhl, Gregory Gol'tsman, Wolfram Pernice
We investigate how the bias current affects the hot-spot relaxation dynamics in niobium nitride. We use for this purpose a near-infrared pump-probe technique on a waveguide-integrated superconducting nanowire single-photon detector driven in the two-photon regime. We observe a strong increase in the picosecond relaxation time for higher bias currents. A minimum relaxation time of (22 ± 1) ps is obtained when applying a bias current of 50% of the switching current at 1.7 K bath temperature. We also propose a practical approach to accurately estimate the photon detection regimes based on the reconstruction of the measured detector tomography at different bias currents and for different illumination conditions...
April 17, 2017: Optics Express
Di Che, Feng Yuan, William Shieh
Semiconductor lasers are versatile optical transmitters in nature. Through the direct modulation (DM), the intensity modulation is realized by the linear mapping between the injection current and the light power, while various angle modulations are enabled by the frequency chirp. Limited by the direct detection, DM lasers used to be exploited only as 1-D (intensity or angle) transmitters by suppressing or simply ignoring the other modulation. Nevertheless, through the digital coherent detection, simultaneous intensity and angle modulations (namely, 2-D complex DM, CDM) can be realized by a single laser diode...
April 17, 2017: Optics Express
Guilong Gao, Kai He, Jinshou Tian, Chunmin Zhang, Jun Zhang, Tao Wang, Shaorong Chen, Hui Jia, Fenfang Yuan, Lingliang Liang, Xin Yan, Shaohui Li, Chao Wang, Fei Yin
A new ultrafast all-optical solid-state framing camera (UASFC) capable of single-shot ultrafast imaging is proposed and experimentally demonstrated. It is composed of an ultrafast semiconductor chip (USC), an optical time-series system (TSS), and a spatial mapping device (SMD) with an USC to transform signal beam information to the probe beam, a TSS to convert the time axis to wavelength-polarization, and a SMD to map wavelength-polarization image to different spatial positions. In our recent proof-of-principle experiment, better performance than ever of this technique is confirmed by giving six frames with ~3 ps temporal resolution and ~30 lp/mm spatial resolution...
April 17, 2017: Optics Express
D H Slichter, V B Verma, D Leibfried, R P Mirin, S W Nam, D J Wineland
We demonstrate superconducting nanowire single photon detectors with 76 ± 4% system detection efficiency at a wavelength of 315 nm and an operating temperature of 3.2 K, with a background count rate below 1 count per second at saturated detection efficiency. We propose integrating these detectors into planar surface electrode radio-frequency Paul traps for use in trapped ion quantum information processing. We operate detectors integrated into test ion trap structures at 3.8 K both with and without typical radio-frequency trapping electric fields...
April 17, 2017: Optics Express
Wen-Bao Sun, Xiao-Fei Yang, Zi-Bo Zhang, Wing-Han Wong, Dao-Yin Yu, Edwin Yue-Bun Pun, De-Long Zhang
Ti<sup>4+</sup>-diffused Zr<sup>4+</sup>/Er<sup>3+</sup>-codoped LiNbO<sub>3</sub> strip waveguide was fabricated on an X-cut LiNbO<sub>3</sub> substrate by thermal diffusion in sequence of Er<sup>3+</sup>, Zr<sup>4+</sup> and Ti<sup>4+</sup>. Secondary ion mass spectrometry study shows that the Ti<sup>4+</sup> ions follow a sum of two error functions in the width direction and a Gauss function in the depth direction of the waveguide...
April 17, 2017: Optics Express
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