Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences
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Analysis the Neolithic Jade Jue Unearthed from Three Sites in Zhejiang
No full textIn order to acquire the fundamental materials science information of the Neolithic jade jue in Taihu Lake basin (for example, the main minerals and hardness), and explore the evolution law of the jade raw material in pace with time and the possible sources of the jade raw materials, this paper takes the jade jues unearthed from three representative Neolithic sites-Tianluoshan, Xiantanmiao and Jiangjiashan in Zhejiang province as the research objects. These jade jues were nondestructively analyzed by X-ray diffraction (XRD) and external beam proton induced X-ray emission (PIXE). The results suggest that the jade jues analyzed were mainly made of fluorite, dickite, chalcedony, muscovite, tremolite and serpentine dated from Hemudu culture to the late Songze culture. Among them, fluorite, chalcedony and dickite accounted for a large proportion and were applied much earlier than tremolite and serpentine. Combined with the previous researches, we discuss the change of characteristics of the jade jue raw materials unearthed from the relative sites along with time, the possible sources of the jade raw materials, and the internal relation between the material science characteristics and processing technique
Movement flatness error measurement based on an astigmatic method
No full textNational Natural Science Foundation of China (NSFC) [51672292, 61627826]The movement flatness error is one of the critical parameters of motorized stage performance. In this work, the measurement of the movement flatness error based on an astigmatic method is proposed, in which the focus error signal is detected and used to analyze the movement flatness error. The theoretical derivation and analysis are presented, and the experimental system is established accordingly. The experimental results indicate that our measurement method and established system exhibit an accuracy of less than +/- 100 nm. The movement flatness error of an x-y stepping motorized stage is measured using the established system, and the movement flatness error profile is mapped; it is determined that the maximum movement flatness error is within 1.3 mu m in our experiment. The proposed method is hence proven to be an effective way of measuring the movement flatness error of motorized stages. (C) 2017 Optical Society of Americ
A diffraction-limited laser of 25/400 Yb3+/Al3+/P5+/F- silica fiber with a zigzag refractive index profile
No full textNational Natural Science Foundation of China [61405215, 61505232]; Youth Innovation Promotion Association of the Chinese Academy of Sciences; National High Technology Research and Development Program of China [2016YFB0402201]; Key Technologies R&D Program of Jiangsu [BE2014001, BE2016005]In this work, a Yb3+/Al3+/P5+/F- co-doped low-NA preform with larger than 0.4 wt.% Yb3+ doping concentration and zigzag refractive index profile was fabricated based on solution doping modified chemical vapor deposition technology. The modality of the preform refractive index profile was simulated based on a circle-symmetry-distribution fiber model. According to the simulation results a step-index 25/400 double cladding fiber with core NA of similar to 0.04 was drawn. Pumped with a 970 nm laser diode, a diffraction-limited oscillator-laser output with similar to 71% slope efficiency and M-2 of similar to 1.06 were achieved at bending diameter. 50 cm after stripping cladding light. For bending diameters less than 50 cm, the laser efficiency measured at stripping cladding light decreases with decrease in bending diameter
Luminescence, scintillation, and energy transfer in SiO2-Al2O3-B2O3-Gd2O3:Ce3+,Pr3+ glasses
No full textNational Research Council of Thailand (NRCT project) [2559A30602048]Ce3+,Pr3+-codoped SiO2-Al2O3-B2O3-Gd2O3 glasses (SABG:Ce,Pr) were prepared by melt quenching under a CO reducing atmosphere. Luminescence properties were investigated under UV and X-ray excitations. A dominant emission band at 430nm belonging to the Ce3+:5d(1)4f transition was observed in the photo- and radio-luminescence spectra. The energy transfer occurs from this Ce3+ band toward the P-3(J) levels of Pr3+ with an efficiency of up to 24%, followed by the reduction of integrated luminescence intensity with an increasing Pr3+ concentration. This result is attributed to the increase in the reabsorption of Ce3+ luminescence and the non-radiative energy transfer toward the P-3(J) levels of Pr3+. The cross-relaxation process within the Pr3+ pairs can further diminish the total luminescence yield at high Pr3+ concentrations. The integral scintillation efficiency and light yield measurements were carried out and compared to the reference Bi4Ge3O12 (BGO) crystal
Threshold power of 1.2 mu m infrared laser by in-band pumped Ho3+ -doped crystal
No full text为探索同带泵浦掺杂Ho~(3+)激光晶体1.2 mum波段红外激光输出,采用掺杂浓度为1 at%的Ho~(3+):LLF激光晶体作为激光增益介质,应用两种典型准三能级理论模型,计算了Ho~(3+)在~5I_6和~5I_8能级间跃迁辐射1.19mum激光的阈值功率,分析了泵浦光和激光束腰半径、激光晶体长度、吸收损耗、腔镜反射率等参量与阈值功率的变化关系,得出了吸收损耗是影响阈值功率最敏感因素的重要结论,确定了泵浦阈值功率的范围,为后续1.2 mum波段红外激光实验研究提供了可靠的理论参考数据.National High-tech R & D Program of China (863 Program) [2015XXXXX]; National Natural Science Foundation of China [61603265]; Project of Shenyang Normal University [L201522]; Training Programs for College Students Innovation and Entrepreneurship [201630614171030]The threshold power of 1.2 mu m laser generated from the Ho3+ :LLF crystal was discussed. Two typical quasi-three-level theoretical models were used to analyze the effectiveness of 1194 nm laser threshold power in the in-band pumping source of 1.15, mu m fiber laser with different parameters, such as the absorption coefficient of laser medium, the laser beam radius, the crystal length and reflectivity of the output mirror. It was found that the re-absorption loss was the most important factor leading to the different results for the two models, and the second model was close to the practice because of the narrow bandwidth pumping beam( <6 nm). The results provided reliable data of Ho3+ -doped1.2 mu m solid-state laser systems for the design and experimental research in further
Tapered simplified modal method for analysis of non-rectangular gratings
No full textU.S. Department of Homeland Security (DHS) [HSHQDC-13-C-B0040]The simplifiedmodal method (SMM) [Opt. Quantum Electron. 37, 309 (2005)] provides a quick, intuitive way to analyze the performance of the gratings of rectangular shapes. For non-rectangular shapes, a version of SMM has been developed [Opt. Lett. 33, 1554 (2008)], but it applies only to the Littrow-mounting incidence case and neglects reflection. Here, we use the theory of mode-coupling in a tapered waveguide to improve SMM so that it applies to non-rectangular gratings at arbitrary angles of incidence. Moreover, this new tapered simplified modal method (TSMM) allows us to properly account for reflected light and requires fewer coupled guided modes to compute the correct diffracted field than required plane wave modes in rigorous coupled wave analysis (RCWA). We present here the analytical development of the theory and numerical simulations, demonstrating the validity of the method by comparing it with RCWA and the finite difference time domain method. (C) 2016 Optical Society of Americ
Compact transient-grating self-referenced spectral interferometry for sub-nanojoule femtosecond pulse characterization
No full textNational Natural Science Foundation of China (NSFC) [11274327, 61521093, 61527821]; Instrument Developing Project of the Chinese Academy of Sciences (CAS) [YZ201538]; Strategic Priority Research Program of the Chinese Academy of Sciences (CAS) [XDB16]The self-referenced spectral interferometry (SRSI) technique, which is usually used for microjoule-level femtosecond pulse characterization, is improved to characterize weak femtosecond pulses with nanojoule based on the transient-grating effect. Both femtosecond pulses from an amplifier with 3 nJ per pulse at 1 kHz repetition rates and femtosecond pulses from an oscillator with less than 0.5 nJ per pulse at 84 MHz repetition rates are successfully characterized. Furthermore, through a special design, the optical setup of the device is even smaller than a palm, which will make it simple and convenient during the application. These improvements extend the application of the SRSI technique to the characterization of femtosecond pulses in a broad range. Not only pulses from an amplifier but also pulses from an oscillator or weak pulses used in ultrafast spectroscopy can be monitored with this SRSI method right now. (C) 2017 Optical Society of Americ
Harmonic generation at air-soil interface by femtosecond laser filament
No full textKey Project from the Bureau of International Cooperation Chinese Academy of Sciences [181231KYSB20160045]; 100 Talents Program of the Chinese Academy of Sciences; State Key Laboratory of High Field Laser Physics; [XDB16]We observe the third-harmonic generation and second-harmonic generation together with element fluorescence from the interaction of a femtosecond laser filament with a rough surface sample (sandy soil) in non-phase-matched directions. The harmonics prove to originate from the phase-matched surface harmonics and air filament, then scatter in non-phase-matched directions due to the rough surface. These harmonics occurr when the sample is in the region before and after the laser filament, where the laser intensity is not high enough to excite the element fluorescence. The observed harmonics are related to the element spectroscopy, which will benefit the understanding of the interaction of the laser filament with a solid and be helpful for the application on filament induced breakdown spectroscopy
Numerical investigation of output beam quality in efficient broadband optical parametric chirped pulse amplification
No full textNational Natural Science Foundation of China [61521093, 61378030]We theoretically analyzed output beam quality of broad bandwidth non-collinear optical parametric chirped pulse amplification (NOPCPA) in LiB3O5 (LBO) centered at 800 nm. With a three-dimensional numerical model, the influence of the pump intensity, pump and signal spatial modulations, and the walk-off effect on the OPCPA output beam quality are presented, together with conversion efficiency and the gain spectrum. The pump modulation is a dominant factor that affects the output beam quality. Comparatively, the influence of signal modulation is insignificant. For a low-energy system with small beam sizes, walk-off effect has to be considered. Pump modulation and walk-off effect lead to asymmetric output beam profile with increased modulation. A special pump modulation type is found to optimize output beam quality and efficiency. For a high-energy system with large beam sizes, the walk off effect can be neglected, certain back conversion is beneficial to reduce the output modulation. A trade-off must be made between the output beam quality and the conversion efficiency, especially when the pump modulation is large since. A relatively high conversion efficiency and a low output modulation are both achievable by controlling the pump modulation and intensity. (C) 2016 Elsevier B.V. All rights reserved
Pure Even Harmonic Generation from Oriented CO in Linearly Polarized Laser Fields
No full textNational Natural Science Foundation of China [11274326, 61521093, 61405222, 11127901]; Chinese Academy of Sciences [XDB16]The first high harmonic spectrum containing only the odd orders was observed in experiments 30 years ago. However, a spectrum containing pure even harmonics has never been observed. We investigate the generation of pure even harmonics from oriented CO molecules in linearly polarized laser fields employing the time-dependent density-functional theory. We find that the even harmonics, with no odd orders, are generated with the polarization perpendicular to the laser polarization when the molecular axis of CO is perpendicular to the laser polarization. The generation of pure even harmonics reveals a type of dipole acceleration originating from the permanent dipole moment. This phenomenon exists in all systems with permanent dipole moments, including bulk crystal and polyatomic molecules