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Sean McDaniel, Fiona Thorburn, Adam Lancaster, Ronald Stites, Gary Cook, Ajoy Kar
We report fabrication and operation of multi-watt level waveguide lasers utilizing holmium-doped yttrium aluminum garnet (Ho:YAG). The waveguides were fabricated using ultrafast laser inscription, which relies on a chirped pulse ytterbium fiber laser to create depressed cladding structures inside the material. A variety of waveguides were created inside the Ho:YAG samples. We demonstrate output powers of ∼2  W from both a single-mode 50 μm waveguide laser and a multimode 80 μm waveguide laser. In addition, laser action from a co-doped Yb:Ho:YAG sample under in-band pumping conditions was demonstrated...
April 20, 2017: Applied Optics
Jeeban Kumar Nayak, Rajan Jha
A graphene-based surface plasmon resonance sensor using D-shaped fiber in anti-crossing has been designed. Silver as a plasmon active metal is followed by graphene, which helps in preventing oxidation and shows better adsorption efficiency to biomolecules. A wavelength interrogation technique based on the finite element method has been used to evaluate performance parameters. Design parameters such as thickness of silver, residual cladding, and GeO<sub>2</sub> dopant concentration have been optimized...
April 20, 2017: Applied Optics
Kawsar Ahmed, Sawrab Chowdhury, Bikash Kumar Paul, Md Shadidul Islam, Shuvo Sen, Md Ibadul Islam, Sayed Asaduzzaman
In this paper, a novel polarization-maintaining single-mode photonic crystal fiber (PCF) has been suggested for terahertz (THz) transmission applications. The reported PCF has five layers of hexagonal cladding with two layers of porous core. The cladding and core territory of the PCF are constituted by circular and elliptical air cavities, accordingly acting as a dielectric medium. Different geometrical parameters of the proposed PCF including pitches and diameters of circular air holes with the major and minor axes of elliptical air cavities being varied with the optimized structure...
April 20, 2017: Applied Optics
M Fischer, P Laheurte, P Acquier, D Joguet, L Peltier, T Petithory, K Anselme, P Mille
Biocompatible beta-titanium alloys such as Ti-27.5(at.%)Nb are good candidates for implantology and arthroplasty applications as their particular mechanical properties, including low Young's modulus, could significantly reduce the stress-shielding phenomenon usually occurring after surgery. The CLAD® process is a powder blown additive manufacturing process that allows the manufacture of patient specific (i.e. custom) implants. Thus, the use of Ti-27.5(at.%)Nb alloy formed by CLAD® process for biomedical applications as a mean to increase cytocompatibility and mechanical biocompatibility was investigated in this study...
June 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Xian Peng, Han Yuan, Wufan Chen, Tao Wang, Lei Ding
Continuous loop averaging deconvolution (CLAD) is one of the proven methods for recovering transient auditory evoked potentials (AEPs) in rapid stimulation paradigms, which requires an elaborated stimulus sequence design to attenuate impacts from noise in data. The present study aimed to develop a new metric in gauging a CLAD sequence in terms of noise gain factor (NGF), which has been proposed previously but with less effectiveness in the presence of pink (1/f) noise. We derived the new metric by explicitly introducing the 1/f model into the proposed time-continuous sequence...
2017: PloS One
Yves Bidaux, Ilia Sergachev, Wolf Wuester, Richard Maulini, Tobias Gresch, Alfredo Bismuto, Stéphane Blaser, Antoine Muller, Jérôme Faist
We demonstrate dispersion compensation in mid-infrared quantum cascade laser frequency combs (FCs) emitting at 7.8 μm using the coupling of a dielectric waveguide to a plasmonic resonance in the top cladding layer of the latter. Devices with group velocity dispersion lower than 110  fs<sup>2</sup>/mm were fabricated, and narrow beatnotes with FWHM linewidths below 1 kHz were measured on the entire operation range. At -20°C, the optical output power reaches 275 mW, and the optical spectrum spans 60  cm<sup>-1</sup>...
April 15, 2017: Optics Letters
Nikolaus Kneidinger, Katrin Milger, Silke Janitza, Felix Ceelen, Gabriela Leuschner, Julien Dinkel, Melanie Königshoff, Thomas Weig, René Schramm, Hauke Winter, Jürgen Behr, Claus Neurohr
Identification of disease phenotypes might improve the understanding of patients with chronic lung allograft dysfunction (CLAD). The aim of the study was to assess the impact of pulmonary restriction and air trapping by lung volume measurements at the onset of CLAD.A total of 396 bilateral lung transplant recipients were analysed. At onset, CLAD was further categorised based on plethysmography. A restrictive CLAD (R-CLAD) was defined as a loss of total lung capacity from baseline. CLAD with air trapping (AT-CLAD) was defined as an increased ratio of residual volume to total lung capacity...
April 2017: European Respiratory Journal: Official Journal of the European Society for Clinical Respiratory Physiology
Hiromi Takiguchi, Soto Asanuma, Junya Kamiyama, Hiroyasu Murata, Yuki Hasegawa, Satoshi Yoshizawa, Hiroki Hotta, Tamao Odake, Tomonari Umemura, Kiichi Sato, Kin-Ichi Tsunoda
A stable two-phase sheath flow using tetrahydrofuran (THF) for an inner flow and water for an outer flow was formed in a glass capillary, and worked as a stable liquid-core/liquid-cladding optical waveguide (THF/water LLW). Although THF and water were miscible with any ratio, the length of the stable THF/water LLW at 0.9 - 2.1 cm s(-1) reached at least 150 mm. The THF/water LLW was applied to the observation of extraction behavior of solvatochromic fluorescence dye, 1-anilino-8-naphtalene sulfonate (ANS), through the THF/water interface...
2017: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
Annelies Leyssens, Daan Dierickx, Eric K Verbeken, Thomas Tousseyn, Stijn E Verleden, Bart M Vanaudenaerde, Lieven J Dupont, Jonas Yserbyt, Geert M Verleden, Dirk E Van Raemdonck, Robin Vos
Post-transplant lymphoproliferative disorder (PTLD) may compromise long-term outcome of lung transplant (LTx) recipients. A case-control study was performed, comparing LTx recipients with PTLD (n=31) to matched recipients without PTLD (Controls, n=62). Risk factors for PTLD and post-transplant outcomes were assessed. PTLD prevalence was 3.9%, time to PTLD 323 (166-1132) days; and 54.8% had early-onset PTLD versus 45.2% late-onset PTLD. At LTx, more Epstein-Barr virus (EBV)-seronegative patients were present in PTLD (42%) compared to Controls (5%) (p<0...
April 6, 2017: Clinical Transplantation
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
Young-Geun Han
Transmission characteristics of periodically surface-corrugated long-period gratings (LPGs) inscribed on photonic crystal fibers (PCFs) using a wet-etching technique were experimentally investigated. A conventional wet method was implemented to periodically engrave the silica cladding region of the PCFs resulting in the periodic surface corrugation in the PCF. After applying the external strain to the PCF with the periodic surface micro-ridges, periodic modulation of refractive index based on the photoelastic effect is induced resulting in the formation of the PCF-based LPG...
December 2017: Nanoscale Research Letters
Nianbing Zhong, Mingfu Zhao, Lianchao Zhong, Shan Li, Binbin Luo, Bin Tang, Tao Song, Shenghui Shi, Xinyu Hu, Xin Xin, Ruohua Wu, Yanyan Cen, Zhengkun Wang
In this work, we present a luminous-exothermic hollow optical element (LEHOE) that performs spectral beam splitting in the visible spectral range for the enhancement of biofilm growth and activity. The LEHOE is composed of a four-layer structure with a fiber core (air), cladding (SiO<sub>2</sub>), coating I (LaB<sub>6</sub> film), and coating II (SiO<sub>2</sub>-Agarose-Medium film). To clarify the physical, optical and photothermal conversion properties of the LEHOE, we determined the surface morphology and composition of the coating materials, and examined the luminous intensity and heating rate at the LEHOE surface...
March 20, 2017: Optics Express
Mohammad Ali Khosrovani Moghaddam, Mehdi Ahmadi-Boroujeni
The effect of dielectric cladding on the waveguiding characteristics of an array of metallic pillars on a metal plane in the sub-terahertz band is explored. Firstly, a 2D structure made up of a metallic grating of infinite lateral width with various dielectric overlays is analytically studied to get more insight into the problem. Then the ideas inferred from the 2D structure are applied to the realistic 3D structure that has a finite lateral width. It is shown that by proper design of the dielectric medium surrounding the metallic structure the modal field confinement can be enhanced in a broad frequency band resulting in a low bending loss...
March 20, 2017: Optics Express
Hyunjun Kim, Randall S Hay, Sean A McDaniel, Gary Cook, Nicholas G Usechak, Augustine M Urbas, Kathleen N Shugart, HeeDong Lee, Ali H Kadhim, Dean P Brown, Benjamin Griffin, Geoff E Fair, Randall G Corns, Santeri A Potticary, Frank K Hopkins, Kent L Averett, David E Zelmon, Triplicane A Parthasarathy, Kristin A Keller
A polycrystalline 1.5% Ho: YAG fiber with a diameter of 31 µm was prepared. Surface roughness from grain boundary grooving was reduced by polishing, which decreased the fiber scattering coefficient from 76 m<sup>-1</sup> to 35 m<sup>-1</sup>. Lasing tests were done on this fiber with a SF57 Schott glass cladding. Lasing was confirmed by spectrum narrowing with threshold pump power lower than 500 mW and a slope efficiency of 7%. To our knowledge, this is the first lasing demonstration from a small diameter polycrystalline ceramic fiber...
March 20, 2017: Optics Express
Putu Pramudita, Hoon Jang, Indra Karnadi, Hwi-Min Kim, Yong-Hee Lee
We propose and demonstrate a novel one-dimensional nanobeam bandedge laser constituted by self-aligned nanoisland quantum-well (QW) structures. The formation of self-aligned InGaAsP nanoislands sandwiched between two InP claddings is the result of selective removal of QW through wet-etching processes. By controlling wet-etching time, we show a good spatial and spectral overlap between the dielectric mode and the self-aligned nanoisland structures leads to the realization of nanobeam bandedge lasers with low-threshold operations and high slope efficiencies...
March 20, 2017: Optics Express
Huanyu Song, Bowen Liu, Yang Li, Youjian Song, Hao He, Lu Chai, Minglie Hu, Chingyue Wang
We develop a practical femtosecond polarization-maintaining fiber laser amplification system with a standard double-cladding fiber technique, enabling 24-fs transform-limited pulses with 1-μJ pulse energy at a 1-MHz repetition rate. The laser system is based on a hybrid amplification scheme. Chirped-pulse amplification is employed in the pre-amplifier stage to supply high-quality pulses with enough energy for the main-amplifier, where nonlinear amplification is utilized to broaden the output spectrum. To obtain a dechirped pulse with high quality and short duration, a pre-shaper is inserted between the two amplification stages to adjust the pre-chirp, central wavelength, and pulse energy of the signal pulses in the main amplifier for optimizing pulse evolution...
April 3, 2017: Optics Express
Shijie Liu, Jianfeng Shang, Yuanlin Zheng, Xianfeng Chen
Efficient optical nonlinear effects in waveguides play an important role in integrated photonic functionalities. The dispersion characteristics need to be well designed to satisfy the phase-matching condition of the interacting waves in waveguides. Here we demonstrate a novel phase-matching process of second-harmonic generation (SHG) in a symmetrical metal-cladding optical waveguide (SMCOW) with a nonlinear guiding layer. Ultrahigh order modes in SMCOWs possess small propagation constants, and can be actively tuned to satisfy the phase-matching condition via free-space coupling...
April 3, 2017: Optics Express
Yuki Tobita, Takeshi Fujisawa, Taiji Sakamoto, Takashi Matsui, Shota Saitoh, Katsuhiro Takenaga, Kazuhiko Aikawa, Shinichi Aozasa, Kazuhide Nakajima, Kunimasa Saitoh
High spatial multiplicity fiber designs are presented for homogeneous and heterogeneous 4LP-mode multicore fibers (MCFs) that support six spatial modes per core. The high-spatial-density 4LP-mode MCF design methodology is explained in detail. The influence of the number of cores on the cladding diameter (D<sub>cl</sub>) and relative core multiplicity factor (RCMF) is investigated. The optimal core designs and MCF layouts with square and triangular lattices maintain glass fiber reliability (maximum D<sub>cl</sub> = 250 μm)...
March 6, 2017: Optics Express
A L Khalaf, P T Arasu, H N Lim, S Paiman, N A Yusof, M A Mahdi, M H Yaacob
A high sensitivity and simple ethanol sensor based on an un-cladded multimode plastic optical fiber (UCPOF) coated with carbon nanotubes (CNTs) for the detection of different concentrations of ethanol in de-ionized water is developed and demonstrated. The UCPOF probe is fabricated by chemically removing the fiber cladding and integrated with CNT as a sensing layer. The effect of surface morphology on the sensor performance is investigated by characterizing another UCPOF coated with GO nanomaterial. The developed fibers are coated with CNTs and GO using drop casting technique...
March 6, 2017: Optics Express
Jesse A Vaitkus, M J Steel, Andrew D Greentree
Spatial adiabatic passage represents a new way to design integrated photonic devices. In conventional adiabatic passage, designs require smoothly varying waveguide separations. Here we show modelling of adiabatic passage devices where the waveguide separation is varied digitally. Despite digitisation, our designs show robustness against variations in the input wavelength and refractive index contrast of the waveguides relative to the cladding. This approach to spatial adiabatic passage opens new design strategies and hence the potential for new photonics devices...
March 6, 2017: Optics Express
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