Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences
Not a member yet
13355 research outputs found
Sort by
Ultrashort pulses-driven dynamics of blisters in Au-coated gratings
No full textNational Natural Science Foundation of China [11604352, 10704079, U1630140, U1430121]Au-coated gratings (ACGs) for chirped pulse compression were irradiated using 800 +/- 35 nm multiple laser pulses with duration of 30 fs. The laser-induced damage threshold (LIDT) of Au-coated gratings decreases from 0.35 J/cm(2) to 0.10 J/cm(2) with the increased pulse shots. The near threshold damage feature of Au-coated gratings at different pulses shows blisters. It is indicated that the gradually increased blister height with increasing multiple pulses on ACGs is caused by the accumulation effect. The damage morphologies combine with simulated results indicate that the damage of the ACGs can be attributed to the pinholes at the base of grating pillars and the separation of gold coating and photoresist gratings caused by the photoresist absorbed the incident laser energy. Therefore, we consider the damage threshold can be enhanced by optimizing coating deposition technology to reduce pinholes density and increase the adhesion between the gold and the photoresist
Research and development of new neodymium laser glasses
No full textThis work presents a brief introduction on three kinds of newly developed Nd3+-doped laser glasses in Shanghai Institute of Optics and Fine Mechanics (SIOM), China. Two Nd3+-doped phosphate glasses with lower thermal expansion coefficient and thermal shock resistance 4 times higher than that of N31 glass are developed for laser processing. Nd:Silicate and Nd: Aluminate glasses with peak emission wavelength at 1061 and 1065 nm, effective emission bandwidth of 34 and 50 nm, respectively, are developed for Exawatt-class laser system application. Fluorophosphate glasses with low nonlinear refractive index (n(2) = 0.6-0.86) and long fluorescence lifetime (430-510 mu s) are investigated for the purpose of decreasing B integral in high-power laser system. The properties of all these glasses are presented and compared with those of commercial neodymium laser glasses
Analysis of the noise in backprojection light field acquisition and its optimization
No full textNational Natural Science Foundation of China (NSFC) [61327902, 61377005]; Recruitment Program of Global Youth Experts; Research Grants Council of the Hong Kong Special Administrative Region, China [HKU714/13]Light field reconstruction from images captured by focal plane sweeping can achieve high lateral resolution comparable to the modern camera sensor. This is impossible for the conventional micro-lenslet-based light field capture systems. However, the severe defocus noise and the low depth resolution limit its applications. In this paper, we analyze the defocus noise in the focal-plane-sweeping-based light field reconstruction technique, and propose a method to reduce the defocus noise. Both numerical and experimental results verify the proposed method. (C) 2017 Optical Society of Americ
Field-free molecular orientation enhanced by tuning the intensity ratio of a three-color laser field
No full textNational Natural Science Foundation of China [61221064, 61078037, 11134010, 61205208, 61521093]; Strategic Priority Research Program of the Chinese Academy of Sciences [XDB16]; International S&T Cooperation Program of China [2016YFE0119300]We theoretically study the field-free molecular orientation induced by a three-color laser field. The three-color laser field with a large asymmetric degree can effectively enhance the molecular orientation. In particular, when the intensity ratio of the three-color laser field is tuned to a proper value of I-3 : I-2 : I-1 = 0.09 : 0.5 : 1, the molecular orientation can be improved by similar to 20% compared with that of the two-color laser field at intensity ratio I-2 : I-1 = 1 : 1 for the same total laser intensity of 2 x 10(13) W/cm(2). Moreover, we investigate the effect of the carrier-envelope phase (CEP) on the molecular orientation and use the asymmetric degree of the laser field to explain the result. We also show the influences of the laser intensity, rotational temperature, and pulse duration on the molecular orientation. These results are meaningful for the theoretical and experimental studies on the molecular orientation
Fluorescence Dynamics of LicT Protein by Time-Resolved Spectroscopy
No full text使用时间分辨荧光方法,结合紫外吸收光谱和稳态荧光光谱技术,测量了LicT蛋白中色氨酸残基的荧光动力学特性,进而对LicT蛋白质激活前后的局部微环境和结构变化进行了研究。LicT蛋白质的激活态使得有关糖类利用的基因转录过程继续进行,促进机体新陈代谢。通过色氨酸残基的荧光发射和寿命的差异判断出激活型蛋白AC 141和野生型蛋白Q 22不同的结构性质和微环境差异。在此基础上,通过衰减相关光谱(DAS)和时间分辨发射光谱(TRES)阐释了两种蛋白色氨酸残基和溶剂的相互作用,说明了激活型AC 141的比野生型Q 22的结构更加紧密。此外,TRES还说明了蛋白中的色氨酸残基存在连续光谱弛豫过程。各向异性结果则对残基和整个蛋白的构象运动进行了阐述,说明了色氨酸残基在蛋白质体系内有独立的局部运动,且在激活型蛋白中该运动更加强烈。In this paper, the fluorescence dynamics of tryptophan residues in LicT protein is investigated by time-resolved fluorescence method combined with UV absorption and steady-state fluorescence spectroscopy. The local microenvironment and structural changes of LicT protein before and after activation are studied. The activated LicT protein AC 141 prevents the antitermination of gene transcription involved in carbohydrate utilization to accelerate the body's metabolism. The structural properties and microenvironment of activated protein AC 141 and wild-type protein Q 22 were determined by different fluorescence emissions and lifetimes of tryptophan residues. The interaction between tryptophan residues and solvent is elucidated by decay associated spectroscopy (DAS) and time-resolved emission spectra (TRES), indicating that upon activation, the structure of AC 141 is more compact than that of wild-type Q 22. In addition, TRES also showed that tryptophan residues in the protein had a continuous spectral relaxation process. Anisotropy results illustrated the conformational motions of residues and whole proteins, suggesting that tryptophan residues had independent local motions in the protein system, and that the motions were more intense in the activated protein
Perovskite CsPb2Br5 Microplate Laser with Enhanced Stability and Tunable Properties
No full textNational Natural Science Foundation of China [11674042, 61475169, 61520106012, 61574024]; National Young 1000 Talents Program of China [0210002102026]; Strategic Priority Research Program of CAS [XDB16]; Fundamental Research Funds for the Central Universities [106112015CDJZR125511, 106112015CDJXY120001, 021000520 2058]; SRF for ROCS, SEM [0210002409003]; 100 Talents Program of Chinese Academy of Sciences (CAS)Recent years have witnessed a surge of research in all-inorganic perovskite nanomaterials for solar cells and light emitting diodes due to their higher chemical stability compared to their hybrid organic-inorganic counterparts. Herein, by combining material synthesis, characterization, optical measurement, and density functional theory based first principles calculation, a type of all-inorganic perovskite CsPb2Br5 microplate with superior crystallinity, enhanced stability, and tunable optical properties is reported. With a robust band gap of approximate to 2.44 eV, CsPb2Br5 microplate exhibits low-threshold amplified spontaneous emission under both one-and two-photon excitation, which is related to its unique spatially distinguished valence/conduction band edge states originating from the intrinsic sandwiched structure. These results are expected to shed new light on future design and development of novel perovskite nanomaterials for optoelectronic devices
Suppression of thermal lens effect in high-pulse-energy Ti:sapphire amplifiers
No full textNational Natural Science Foundation of China (NSFC) [11127901, 10734080, 61521093, 60908008, 61078037]; Youth Innovation Promotion Association CASIn high-pulse-energy Ti:sapphire amplifiers with moderate repetition rate, the thermal lens effect can significantly decrease the energy extraction efficiency and increase the risk of optical damage. A new method, without introducing any additional components, is proposed to suppress the thermal lens effect in such amplifiers. By utilizing a particularly designed beam expander before the amplifier, specific expanding ratio and beam divergence can be introduced to the injected seed pulses, which can improve the spatial matching between the seed pulses and the pump pulses, and thus enhance the energy extraction efficiency. The enhancement of the energy extraction efficiency has reached approximately 10% in our experimental four-pass Ti:sapphire amplifier, and the good agreement between theoretical and experimental results also demonstrates the validity and feasibility of this method. (C) 2016 Elsevier Ltd. All rights reserved
Ultrafast multi-MeV gamma-ray beam produced by laser-accelerated electrons
No full textNational Natural Science Foundation of China [11335013, 11505264, 11374317]; Chinese Academy of Sciences [1701521X00, XDB16]; Ministry of Science and Technology of the People's Republic of China [2016YFA0401102]Ultrafast multi-MeV high-flux gamma-ray beams have been experimentally produced via bremsstrahlung radiation of laser-accelerated energetic electrons through millimeter-thick copper targets. By optimizing the electron bunches to the charge of 10 nC in a clustering argon gas target, the obtained gamma-ray beam significantly increases to 10(10) photons per shot. The gamma-ray beam spectrum has been measured using a differential filtering detector and has a broad spectrum up to 15 MeV, which is approximately consistent with the Geant4 simulation. The generated high-flux high-energy gamma-ray beams are promising sources for photonuclear reaction, non-destructive inspection and clinical applications. Published by AIP Publishing
Visible perfect reflectors realized with all-dielectric metasurface
No full textScience and Technology Development Fund of CAEP [2014A0302014]Highrefractive index dielectric material with negligible absorption loss can offer strong confinement of light, providing a potential alternative to plasmonic materials at optical frequencies. Here, we demonstrate perfect reflectors with unit reflection (over 99%), by utilizing the Mie resonances of high index amorphous titanium dioxide (alpha TiO2) metasurface arrays. Full-wave simulation and realistic optical constants analysis show that, these perfect reflectors exhibiting (magnetic or electric) dipole resonance can produce a perfect magnetic conductor (PMC) or a perfect electric conductor (PEC). Specifically, such a PMC mirror does not reverse the phase (phi, = 0) of the reflected electric field, resulting in the standing wave close to the mirror has an enhanced maxima field. Therefore, an object placed closely to the surface of a PMC will have a significant stronger interaction with electric field than that placed to a PEC. This unique PMC metasurface serving as back reflectors may enhance light absorption in devices with thin active films, such as solar cells, light-emitting diodes and biosensor devices
Wavelength scaling of atomic nonsequential double ionization in intense laser fields
No full textNational Basic Research Program of China Grant [2013CB922201]; NNSF of China [11334009, 11425414, 11527807]Experimental and theoretical investigations of the wavelength dependence of the nonsequential double ionization (NSDI) process of the xenon atom in intense laser fields are reported. The observed wavelength dependence of the ratio Xe2+/Xe+ deviates significantly from the prediction of the three-step model of ionization (sometimes called the "simple-man" model), both in the slope of the overall decrease with increasing wavelength and in the existence of some pronounced humps. A semiclassical model calculation reproduces the changing slope of the overall decrease, which is due to the interplay of wave-packet diffusion, Coulomb focusing, and a closely related Coulomb defocusing effect of the liberated electron. The hump is beyond the scope of the semiclassical model