Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences
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2 mu m emission of PbF2 single crystal co-doped with Ho3+/Yb3+ ions
No full textNational Natural Science Foundation of China [6147506711404332, 51302283, 51472257]; Guangdong Project of Science and Technology Grants [2014B090903014, 2014B010131004, 2014B010124002, 2015B090901014, 20168090917002, 20168090926004]; China Nonferrous Metal Guilin Research Institute of Geology for Mineral Resources [2016-K-02]; Guangzhou Project of Science and Technology Grants [201508010021]Single crystal of Ho3+/Yb3+ co-doped PbF2 has been grown successfully by the conventional technique modified Bridgman method. The spectral parameters of HO3+ were calculated based on the Judd-Ofelt theory. The transition probabilities, radiative lifetime, and branching ratios were also estimated in detail by the J-O parameters obtained. The 2 mu m emission characteristic and fluorescence lifetime of the I-5(7), manifold upon excitation of a conventional 970 nm laser diode were measured and investigated. Fuchtbauer-Ladenburg theory was applied to calculate the absorption, emission, and gain cross sections of I-5(7) -> I-5(8) transition. Based on examination of spectroscopic parameters evaluated, we suggest Ho3+/Yb3+ co-doped PbF2 crystal is a promising candidate for efficient 2 mu m laser. (C) 2017 Elsevier B.V. All rights reserved
Exfoliation of Stable 2D Black Phosphorus for Device Fabrication
No full textState Key Laboratory of Organic-Inorganic Composites [oic-201503005]; Fundamental Research Funds for the Central Universities [buctrc201525]; Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, CAS; NSFC [61675217, 61522510]; Strategic Priority Research Program of CAS [XDB16030700]; Key Research Program of Frontier Science of CAS [QYZDB-SSW-JSC041]; Program of Shanghai Academic Research Leader [17XD1403900]; Youth Innovation Promotion Association, CASDiscovering stabilizers that protect phosphorene from oxidative degradation is critically required for dispersion processing of black phosphorus (BP). It is equally important to also find environmentally friendly, low-cost, and practical exfoliating media. Herein, we demonstrate the yield of remarkably stable phosphorene by coating with a polymer to shield the nanosheets from reaction with water and air. The polymer shell suppresses the rate of BP degradation more efficiently than previously reported systems. We present for the first tithe a simple kinetic model for exfoliation of BP in polyvinylpyrrolidone (PVP) ethanol solution that appears to quantitatively fit BP exfoliation data, and it illuminates mechanistic aspects of exfoliation. Exfoliated flakes consist of a high level of 51% crystalline single layers that are free from structural disorder or oxidation. A successive centrifugation and redispersion strategy is developed affording dispersions with high phophorene-to-stabilizer ratio, which is very useful for further applications. We also demonstrate that PVP-stabilized phosphorene dispersions possess saturable absorption at both 515 and 1030 nm, which have potential use as ultrafast broadband absorbers. Furthermore, such phosphorene dispersions were processed to prepare new metal/phosphorene nanocomposites that have potential for use as electrocatalysts in electrolytic cells
Fabrication of transparent yttria ceramics by alcoholic slip-casting
No full textNational Youth Natural Science Foundation of China [61405221, 51302284]; China Scholarship CouncilY2O3 transparent ceramics were prepared from alcoholic slurries of Y2O3 nanopowders via a slip-casting method to avoid the hydrolysis issue. Polyvinyl pyrrolidone (PVP), polyethylene glycol (PEG) and polyethylenimine (PEI) were used as dispersants to improve the rheological properties of the slurries. It was found that PEI is the most effective dispersant in ethanol. The adsorbed amount of PEI was evaluated by infrared absorption and rheology measurements. Y2O3 slurry with a solid loading of 20.8 vol% and a viscosity of < 0.1 Pa s at the shear rate of 10 s(-1) was obtained using 1.5 wt% PEI. The slurry yielded a homogeneous green body, and finally resulted in a high-quality Y2O3 ceramic with the in-line transmittance of 80% at 800 nm
Femtosecond laser induced damage of pulse compression gratings
No full textNational High Technology Research and Development Program of China; National Natural Science Foundation of China [10704079, 11304328, U1430121]; China Academy of Engineering Physics [U1430121]Laser induced damage of Au-coated gratings (ACG) and metal multilayer dielectric gratings (MMDG) for pulse compression were measured using 800 35 nm femto-laser with pulse width of 30.2 fs. The -1st order diffraction efficiency of the ACG is over 90% in wavelength range from 700 to 1000 nm. The MMDG has a 148 nm bandwidth (750-897 nm) with -1st order diffraction efficiency greater than 90%. The laser damage experiment on grating samples was performed in air for single-shot damage. The single-shot damage threshold of the ACG and MMDG was determined to be 0.32 0.02 J/cm(2) and 0.31 0.02 J/cm(2), respectively. The damage morphologies of the ACG revealed that the damage was attributed to the pinholes at the base of the, grating pillars and the weak adhesion between metal layer and photoresist gratings layer. The damage feature combined with near field distribution of MMDG indicated that the damage was due to the nonlinear ionization process of the valence electrons in HfO2 film. According to analysis results, the laser damage resistance of the ACG can be enhanced through avoiding the appearance of pinholes and increasing adhesion between metal layer and photoresist layer. And for the MMDG, good performance of HfO2 film, low near field enhancement and single HfO2 grating structures may increase its laser damage resistance. (C) 2017 Elsevier Ltd. All rights reserved
Improving the laser-induced damage threshold of 532-nm antireflection coating using plasma ion cleaning
No full textNational Science Foundation of China [61505227]; Youth Innovation Promotion Association of the Chinese Academy of SciencesBK7 glass substrates were precleaned by different cleaning procedures before being loaded into a vacuum chamber, and then a series of plasma ion cleaning procedures were conducted at different bias voltages in the vacuum chamber, prior to the deposition of 532-nm antireflection (AR) coatings. The plasma ion cleaning process was implemented by the plasma ion bombardment from an advanced plasma source. The surface morphology of the plasma ion-cleaned substrate, as well as the laser-induced damage threshold (LIDT) of the 532-nm AR coating was investigated. The results indicated that the LIDT of 532-nm AR coating can be greatly influenced by the plasma ion cleaning energy. The plasma ion cleaning with lower energy is an attractive method to improve the LIDT of the 532-nm AR coating, due to the removal of the adsorbed contaminations on the substrate surface, as well as the removal of part of the chemical impurities hidden in the surface layer. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE
Lasing improvement of Yb: phosphate glass with GeO2 modification
No full textNational Natural Science Foundation of China [61177083]A series of GeO2 modified Yb: phosphate glasses were studied, covering thermal, optical, and fluorescence properties relevant to lasing performance. The host phosphate glass modified by introducing a second glass former, GeO2, was shown to have improved thermal stability, i.e., higher glass transition temperature (T-g) and lower coefficient of thermal expansion (CTE). Enlargement of Yb3+ E-2(7/2): Stark splitting, broadening of effective fluorescence linewidth (Delta lambda(eff)) and longer fluorescent lifetime (if) were also achieved at the same time, whereas emission cross section (Gem) of the modified glasses were kept nearly constant. Selective laser experiments were performed; while the baseline host phosphate glass failed in lasing, a GeO2-modified phosphate glass was able to deliver 370 mW laser output at 1063 nm. Significant improvement of the lasing performance was further demonstrated using a newly designed GeO2-modified Yb: phosphate glass based on our study, which demonstrated 724 mW laser output at 1063 nm. The overall results from our study showed that germanium phosphate glass system can be developed as a promising material for high energy, large scale Yb3+ laser
Study of the Key Technology of Ghost Imaging Based on Rosette Scanning
No full textNational Basic Research Program of China (973 Program) [2015CB352004]; National Natural Science Foundation of China [61405115]; Natural Science Foundation of Shanghai [14ZR1428400]; Innovation Project of Shanghai Municipal Education Commission [14YZ099]Ghost imaging offers great potential, with respect to standard imaging, for imaging objects in optically harsh or noisy environments. It can solve the problems that are difficult to solve by conventional imaging techniques. Recently, it has become a hot topic in quantum optics. In this paper, we propose a scheme for ghost imaging based on rosette scanning, named rosette ghost imaging. Sampling a small area sampling instead of the whole object, the instantaneous field of view of rosette scanning is used as the modulation light field in ghost imaging. This scheme reduces energy loss, the number of samples, and the sampling time, while improving the quality of the reconstructed image
Dissociative photoionization of 1,2-dichloroethane in intense near-infrared femtosecond laser field
No full textNatural Science Foundation of Shanghai [16ZR1448100]; National Natural Science Fund [11604046, 51132004, 11474096]We experimentally demonstrate the dissociative photoionization of 1,2-C2H4Cl2 molecules in femtosecond laser field by time-of-flight mass spectrum and dc-slice imaging technology. Our results show the low kinetic energy components are from the dissociative ionization process of singly charged molecular ions, and the positive charge assignment are greatly influenced by the appearance energy of the fragment ions. The high kinetic energy components result from Coulomb explosion of multi-charged molecular ions, and the different angular distribution of these fragments along C-C and C-Cl bond dissociation can be explained by the potential energy surfaces of the molecular ions. (C) 2016 Elsevier B.V. All rights reserved
Generation of 300 nm bandwidth 0.5 mJ pulses near 1 mu m in a single stage gas filled hollow core fiber
No full textJapan Society for the Promotion of Science (JSPS) KAKENHI [JP26287145, JP15K04696]; Photon Frontier Network of the Ministry of Education, Culture, Sports, Science and Technology (MEXT)A simple and compact spectral-broadening system is presented that is based on a single-stage statically pressurized Ar filled core fiber. By optimizing the inner diameter of the core fiber, a bandwidth of 300 nm is obtained. This is the broadest bandwidth known to date with millijoule level energy near the 1- mu m wavelength by a single stage filled core fiber. (C)2017 Optical Society of Americ
GERMANIUM FABRY-PEROT INTERFEROMETER HEATED WITH A ND:YAG LASER
No full textNational Basic Research Program of China [2011CB808101]; National Natural Science Foundation of China [61078037, 11127901, 11134010, 11204328]; Natural Science Foundation of Shanghai [15ZR1444900]; International S&T Cooperation Program of China [2011DFA11300]We report on a germanium Fabry-Perot interferometer heated with a Nd: YAG laser. The transmission property of the laser-heated germanium Fabry-Perot interferometer has been investigated experimentally and theoretically. The transmission of CO2 laser through the germanium Fabry-Perot interferometer varied with Nd: YAG laser heating. The theoretical results are in good agreement with the experimental results. The technique of laser-heated germanium Fabry-Perot interferometry is promising for applications in laser modulation and detection. (C) 2017 Wiley Periodicals, Inc