2015
2015
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Record 373 of
Title:Optical design for a kind of simply processed and installed off-axis three-reflection
Author(s):Gao, Duorui(1); Hu, Hui(1); Wang, Wei(1); Xie, Xiaoping(1); Han, Biao(1); Su, Yulong(1); Fu, Qiang(2)Source: Zhongguo Jiguang/Chinese Journal of Lasers Volume: 42 Issue: 6 DOI: 10.3788/CJL201542.0616001 Published: June 10, 2015Abstract:An unobscured reflective optical system with two- mirrors three- reflective is described to reduce off- axis difficulty processing. A piece of aspherical mirrors instead of the primary mirror and third mirror in the traditional off-axis three-reflective system, that is one mirror achieve two mirrors' responsibility, the complexity of the optical processing is reduced, as well as the difficulty of the alignment. Based on the aberration theory of three reflective system, formula of the coaxial structural is deduced, the equation for the system is obtained as well. The parameters of the unobscured off-axial two-mirrors system are that focal length of 1000 mm, F number is 10, field of view is 2° × 0.4°, and the surface type of the two mirrors are all quadric surface. From the figure of spot digram, modulation transfer function, point spread function and encircled energy, it is observed that image quality is good and energy is more concentrated. The optical system is designed with small volume, simple structure, and light weight. ?, 2015, Science Press. All right reserved.Accession Number: 20153501209604 -
Record 374 of
Title:Highly efficient nonlinear ellipse rotation in bulk SrTiO3 crystal and its applications
Author(s):Sun, Qibing(1); Liu, Hongjun(1); Huang, Nan(1); Wang, Zhaolu(1); Li, Shaopeng(1); Han, Jing(1)Source: Laser Physics Volume: 25 Issue: 12 DOI: 10.1088/1054-660X/25/12/125403 Published: December 2015Abstract:We investigated the highly efficient, nonlinear ellipse rotation (NER) effect in bulk SrTiO3 crystal, which provides practical application as a pulse cleaner for ultrashort pulses. A highly stable, ultrafast NER effect was realized by using a bulk SrTiO3 crystal with a fast response time, strong optical Kerr effect, high damage threshold, and wide transmission wavelength range. Transmissivity higher than 30% was obtained at a level of several mJ, in which the temporal contrast can be enhanced by about three orders of magnitude. This provides a simple and feasible technology for improving the temporal contrast for the ultrahigh power laser system. ? 2015 Astro Ltd.Accession Number: 20154801610320 -
Record 375 of
Title:A forming method for improving surface integrity of film cooling holes
Author(s):Zhao, Hua-Long(1); Zhou, Ren-Kui(1); Zhao, Hong-Yan(2); Zhao, Wei(1); Zhu, Wen-Yu(1); Yang, Xiao-Jun(1); Li, Ming(1); Deng, Yue(1)Source: Hangkong Dongli Xuebao/Journal of Aerospace Power Volume: 30 Issue: 3 DOI: 10.13224/j.cnki.jasp.2015.03.015 Published: March 1, 2015Abstract:In order to solve the problems of forming process of turbine blade of aero-engine film cooling holes, such as severe heat effect, a helix drilling and spiral drilling processing method for microholes by ultrafast laser was proposed, and a double power laser system was designed for machining of film cooling holes efficiently and without heat effect; the reason of heat effects was analyzed from two aspects of action mechanism and actual machining process; the main influential factors were pointed out and the optimization of process parameters and experimental verification targeting at these factors were processed using DD6 material. The experimental results show that the composite processing method using 500 fs laser and microseconds laser can increase fine drilling efficiency about 10 times, and can also process the film cooling holes on turbine blades without recast layer and micro-cracks; the process parameters include beam scanning speed of 2400 r/min, overlap rate of 12%, feeding amount of 5 μm, repetition frequency of 20 kHz and coaxial blow with the air pressure of 0.6 Pa. They also show that ultrafast laser with reasonable process parameters and processing methods can process film cooling holes without heat effects, so it is an effective technological method to improve the surface integrity of film cooling holes. ?, 2015, BUAA Press. All right reserved.Accession Number: 20151800809966 -
Record 376 of
Title:On laser-induced damage features in an ultraviolet (UV) Fluorophosphate glass when irradiated with a nanosecond laser beam
Author(s):Fu, L.-L.(1,2); Wei, W.(1); Zhang, C.-M.(2); Peng, B.(1)Source: Lasers in Engineering Volume: 30 Issue: 5-6 DOI: Published: 2015Abstract:In this study a novel ultraviolet (UV) window material, fluorophosphate glass, was prepared by the melt-quenching method. The laser-induced damage (LID) feature of fluorophosphate glass was measured using laser damage experiments, atomic force microscopy (AFM), and scanning electron microscopy (SEM). The results show that fluorophosphate glass has a high ultraviolet transmittance (88%) at 351.00 nm. And the laser-induced damage threshold (LIDT) of the fluorophosphate glass is almost 7.0 J/cm2, which is more than 2 times higher than that of fused silica (3.2 J/cm2) irradiated with a 8 ns and 351.00 nm laser by the same processing method. In addition, AFM and SEM images indicate that the damage is also insensitive to the surface roughness of fluorophosphate glass. ?2015 Old City Publishing, Inc.Accession Number: 20151300686554 -
Record 377 of
Title:Enhanced optical properties and the origin of carrier transport in BiFeO3/TiO2 heterostructures with 109° domain walls
Author(s):Feng, Hong-Jian(1); Wang, M.(1); Liu, F.(2); Duan, B.(1); Tian, J.(2); Guo, X.(2)Source: Journal of Alloys and Compounds Volume: 628 Issue: DOI: 10.1016/j.jallcom.2014.11.211 Published: April 15, 2015Abstract:The absorption coefficient in the BiFeO3/TiO2 bilayer film prepared by simple sol-gel method has been significantly improved relative to BiFeO3 and TiO2 film. Terahertz-radiation emission presents a direct evidence for the photon-induced carrier transport in the heterostructures. First-principles calculations agree well with the experiments and present an unambiguous explanation for the charge carrier transport and the enhanced absorbance. It is induced by the large electrostatic potential drop in the interface with the 109°domain walls and the reduced recombination of electron-hole pairs in the BiFeO3 side of the heterostructure. This work provides a new route toward designing novel photovoltaic heterostructures with high efficiency. ? 2014 Elsevier B.V.Accession Number: 20150300423952 -
Record 378 of
Title:A kind of transmission-type lens using in x-ray band
Author(s):Li, Yan(1); Li, Xiao-Li(1); Xu, Xiangyan(2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9449 Issue: DOI: 10.1117/12.2075444 Published: 2015Abstract:The negative refractive index characteristics of one-dimensional photonic crystal consisted by Fibonacci multi-layer films has been studied by numerical method. The refractive indices for two materials, which are used to construct the Fibonacci multi-layer films, are 0.920 and 0.999, respectively. The calculation result shows that, on one hand, there are several negative refractive index zones for this kind of photonic crystal even if the refractive indices are very small; on the other hand, the difference is very large for the frequency between the zones. As an example, a kind of transmission-type plano-concave lens is designed. The simulation of the electromagnetic field distribution for the lens demonstrates that the lens can focus the incoming X-ray radiation. At the same time, the calculation of the absorption strength and refractive indices for real materials shows that not only there are large differences for the absorption strength with different materials, but also the refractive indices for real materials are different in X-ray band. Obviously, the characteristics above support a kind of transmission-type lens using in X-ray.. ? 2015 SPIE.Accession Number: 20151100635500 -
Record 379 of
Title:A 3000W 808nm QCW G-stack semiconductor laser array
Author(s):Zhang, Pu(1); Wang, Jingwei(2); Hou, Dong(2); Wang, Zhenfu(1); Xiong, Lingling(1); Liu, Hui(1); Nie, Zhiqiang(1); Liu, Xingsheng(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9255 Issue: DOI: 10.1117/12.2065663 Published: 2015Abstract:With the improvement of output power, efficiency and reliability, high power semiconductor lasers have been applied in more and more fields. In this paper, a conduction-cooled, high peak output power semiconductor laser array was studied and developed. The structure and operation parameters of G-Stack semiconductor laser array were designed and optimized using finite element method (FEM). A Quasi-continuous-wave (QCW) conduction-cooled G-Stack semiconductor laser array with a narrow spectrum width was fabricated successfully. ? 2015 SPIE.Accession Number: 20151000608778 -
Record 380 of
Title:All-fiber dual-wavelength laser delivering two types of solitons
Author(s):Li, W.L.(1)Source: Laser Physics Volume: 25 Issue: 5 DOI: 10.1088/1054-660X/25/5/055102 Published: May 1, 2015Abstract:We have proposed a compact all-fiber dual-wavelength laser based on a fiber Bragg grating (FBG) and semiconductor saturable absorber mirror (SESAM). The proposed laser mode locked by single-walled carbon nanotubes (SWNTs) delivers two kinds of solitons with pulse durations of ～1 ps and ～20 ps. The spectral width of the longer soliton pulses is ～0.14 nm, which attributes to the narrow bandwidth of the FBG. Shorter pulses with a spectral width of ～4 nm are mainly determined by the cavity length and intracavity dispersion. Our method provides a simple, stable, low-cost, and dual-scale ultrafast-pulsed laser source suitable for practical applications in optical communications and sensing. ? 2015 Astro Ltd.Accession Number: 20151800807607 -
Record 381 of
Title:Nanotube-mode-locked linear-cavity fiber laser delivering switchable ultrafast solitons
Author(s):Han, X.X.(1)Source: Laser Physics Volume: 25 Issue: 2 DOI: 10.1088/1054-660X/25/2/025104 Published: February 1, 2015Abstract:We propose a linear-cavity switchable fiber laser based on a single-wall carbon nanotube mode-locker for the first time to the best of our knowledge. Two chirped fiber Bragg gratings (CFBGs) in series and an optical circulator are employed as end mirrors of the linear cavity. The linear-cavity fiber laser is simple and cost-efficient. By adjusting the polarization controllers, a switchable mode-locking operation is obtained at 1551.3 and 1557.9 nm respectively, corresponding to the central wavelengths of two series-wound CFBGs. The pulse duration and spectral bandwidth of ultrafast solitons are ～4.4 ps and ～0.65 nm for the short wavelength operation at 1551.3 nm and ～3.9 ps and ～0.71 nm for the long wavelength operation at 1557.9 nm, respectively. Our experimental observations are well confirmed by the numerical results. The linear-cavity all-fiber laser reduces the cost and is very attractive for ultrafast optics. ? 2015 Astro Ltd.Accession Number: 20150400457305 -
Record 382 of
Title:Evanescent-field interaction with carbon nanotubes for a multi-wavelength ultrafast all-fiber laser
Author(s):Han, X.X.(1)Source: Laser Physics Volume: 25 Issue: 5 DOI: 10.1088/1054-660X/25/5/055104 Published: May 1, 2015Abstract:We report on the experimental observation of multi-wavelength operations based on the evanescent-field interaction with carbon nanotubes (CNTs). The saturable absorber (SA) is fabricated by depositing CNTs on a D-shaped fiber (DF). In the experiment, switchable dual-wavelength picosecond solitons with central wavelengths of 1532.2, 1556.6 nm and 1529.4, 1531.0 nm are achieved. Several single wavelength operations are also delivered by the all-fiber laser. Single- and multi-wavelength pulse emissions are effectively controlled by changing the pump power and optimizing the polarization controller. Our experiment demonstrates that the DF-SA can work as a versatile mode locker in ultrafast lasers. The flexible all-fiber laser is convenient and attractive for practical applications such as fiber optic sensing and photonic component characterization. ? 2015 Astro Ltd.Accession Number: 20151800807605 -
Record 383 of
Title:Supercontinuum generation in strip/slot hybrid waveguide with flat and low dispersion
Author(s):Zhang, Yuchao(1); Liu, Hongjun(1); Sun, Qibing(1); Huang, Nan(1); Wang, Zhaolu(1)Source: Applied Optics Volume: 54 Issue: 15 DOI: 10.1364/AO.54.004850 Published: May 20, 2015Abstract:A strip/slot hybrid waveguide with double horizontal silicon nanocrystals slots is proposed to achieve flat and low dispersion with four zero dispersion wavelengths. By tuning structural parameters of the waveguide, dispersion tailoring is fully characterized. The flat dispersion varying between -13 and 14 ps/(nm · km) is obtained over an 845 nm bandwidth. A broadband supercontinuum spectrum, spanning from 1.15 to 3.65 μm in the -15 dB level, was generated in this waveguide pumped by a femtosecond pulse at 1.86 μm. Results indicate that the waveguide has great potential in near- and mid-infrared nonlinear applications. ? 2015 Optical Society of America.Accession Number: 20153801293036 -
Record 384 of
Title:Real-time visualization of fluidic field using point-diffraction digital holographic interferometry
Author(s):Min, Junwei(1); Gao, Peng(1); Guo, Rongli(1); Zhou, Meiling(1); Yao, Baoli(1)Source: Digital Holography and Three-Dimensional Imaging, DH 2015 Volume: Issue: DOI: 10.1364/dh.2015.dw2a.17 Published: May 18, 2015Abstract:The dynamic fusion process of two different fluidic fields is visualized and quantitatively analyzed by using common-path point-diffraction digital holographic interferometry. The measurement results are compared with that from other techniques, verifying the practicability of the proposed method.Accession Number: 20152701006766