Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences
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Containing intense laser light in circular cavity with magnetic trap door
No full textNNSFC [11305264, 11275269, 11374262, 11375265, 11475260, 91230205]; Open Fund of the State Key Laboratory of High Field Laser Physics at SIOM; Research Program of NUDTIt is shown by particle-in-cell simulation that intense circularly polarized (CP) laser light can be contained in the cavity of a solid-density circular Al-plasma shell for hundreds of light-wave periods before it is dissipated by laser-plasma interaction. A right-hand CP laser pulse can propagate with almost no reflection and attenuation into the cavity through a highly magnetized overdense H-plasma slab filling the entrance hole. The entrapped laser light is then multiply reflected at the inner surfaces of the slab and shell plasmas, slowly losing energy to the latter. Compared to that of the incident laser, the frequency is only slightly broadened and the wave vector slightly modified by the appearance of weak nearly isotropic and homogeneous fluctuations. Published by AIP Publishing
Crater-like structures induced by intense laser
No full textNational Natural Science Foundation of China [11125526, 11335013, 11575274]; Strategic Priority Research Program of the Chinese Academy of Sciences [XDB16]; Ministry of Science and Technology of the People's Republic of China [2016YFA0401102]Crater-like structures are experimentally studied with an ultrashort, ultraintense laser pulse with an intensity of 1.5 x 10(18) W/cm(2), irradiating borosilicate glass targets, which extends laser-induced craters to the region of relativistic intensities. The morphology of the crater-like structures is measured accurately using a three-dimensional laser scanning confocal microscope and a scanning electron microscope. The experimental results indicate that a circular bowl shape is formed with a depth-to-diameter ratio of about 1/5, which is similar to that of meteorite impact craters. A plasma fireball model is applied to analyze the experimental results. Studies show that catastrophic asteroid strikes may be investigated by irradiating foils with intense laser pulses. (C) 2017 Author(s)
Dispersion management of the SULF front end
No full textNational Basic Research Programme of China [011CB808101]; Strategic Priority Research Programme of the Chinese Academy of Sciences [XDB16]; National Natural Science Foundation of China [61521093, 61078037, 11127901, 11134010, 61205208, 11204328]To manage dispersion of the front end in the Shanghai Superintense Ultrafast Laser Facility (SULF), which is a largescale project aimed at delivering 10 PW laser pulses, a stretcher based on a combination of a grating and a prism (grism) pair is inserted between an Offner-triplet-type stretcher and a regenerative amplifier to reduce high-order dispersion introduced by optical materials at the amplification stage. The alignment of the grism pair is implemented by controlling the far-field pattern of the output beam of the grism pair. The energy of the front end reaches up to 7 J at a 1-Hz repetition rate. Experimental results show that the pulse duration can be compressed to 22.4 fs and the spectral distortion over the spectrum is less than 2.25 rad
Electron localization of linear symmetric molecular ion H-3(2+)
No full textNational Natural Science Foundation of China [11127901, 61521093, 11134010, 11227902, 11222439, 11274325]; National Basic Research Program of China [2011CB808103]Electron localization in the dissociation of the symmetric linear molecular ion H-3(2+) is investigated. The numerical simulation shows that the electron localization distribution is dependent on the central frequency and peak electric field amplitude of the external ultrashort ultraviolet laser pulse. When the electrons of the ground state are excited onto the 2p sigma(2)Sigma(+)(u) by a one-photonprocess, most electrons of the dissociation states are localized at the protons on both sides symmetrically. Almost no electron is stabilized at the middle proton due to the odd symmetry of the wave function. With the increase of the frequency of the external ultraviolet laser pulse, the electron localization ratio of the middle proton increases, for more electrons of the ground state are excited onto the higher 3p sigma(2)Sigma(+)(u) state. 50.9% electrons of all the dissociation events can be captured by the middle Coulomb potential well through optimizing the central frequency and peak electric field amplitude of the ultraviolet laser pulse. Besides, a direct current (DC) electric field can be utilized to control the electron motions of the dissociation states after the excitation of an ultraviolet laser pulse, and 68.8% electrons of the dissociation states can be controlled into the middle proton
Energy Scaling of Terahertz Pulses Produced through Difference Frequency Generation
No full textNational Natural Science Foundation of China [11274326, 61221064, 61405222, 11134010, 11127901]; Shanghai Sailing Program [14YF1406200]We study the energy scaling of terahertz (THz) emission through difference frequency generation of near-infrared pulses, and demonstrate that Gigawatt few-cycle THz transients at the central frequency of 30 THz are produced from GaSe crystal pumped by two pulses at 1.65 and 1.95 micrometers, with the high quantum yield of 28%. Our analysis indicates that the high yield of DFG originates from the largely reduced group velocity mismatch as the long-wavelength pumping pulses are employed
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
On-chip electro-optic tuning of a lithium niobate microresonator with integrated in-plane microelectrodes
No full textNational Basic Research Program of China (Program 973) [2014CB921300]; Natural National Science Foundation of China (NSFC) [61275205, 61590934, 61505231, 61405220]; Fundamental Research Funds for the Central Universities; Open Fund of the State Key Laboratory on Integrated Optoelectronics [IOSKL2015KF34]We demonstrate electro-optic tuning of an on-chip lithium niobate microresonator with integrated in-plane microelectrodes. First, the metallic microelectrodes were fabricated on the substrate using a femtosecond laser. Then high-Q lithium niobate microresonator located between the microelectrodes was further fabricated by femtosecond laser direct writing accompanied by focused ion beam milling. Thanks to the efficient design, a high electro-optical tuning coefficient of 3.41 pm/V has been obtained. (C) 2017 Optical Society of Americ
Parasitic lasing in large aperture Ti: sapphire chirped pulse amplifier
No full textNational Natural Science Foundation of China (NSFC) [61378030, 61521093]We research some properties of parasitic lasing (PL) in the Ti: sapphire chirped pulse amplifier with the crystal diameter of 100 mm. The evolutionary process from the spontaneous emission to the PL and its influence on amplified output energy, spectrum, and beam profile are experimentally measured. The threshold of PL in the crystal is 22 J, and the output signal can still keep rising with the pump when the pump energy is below 38 J. The PL has no obvious impact on the output spectrum and beam profile besides the energy
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
Persistent luminescent nanoparticles as energy mediators for enhanced photodynamic therapy with fractionated irradiation
No full textNational Natural Science Foundation of China (NSFC) [11274327, 61521093, 61527821, 11575276]; Chinese Academy of Sciences [YZ201538, QYZDB-SSW-JSC002]; Shanghai Institute of Optics and Fine Mechanics [1603051J00]; Shanghai Sailing Program [17YF1421300]The excitation wavelengths of most porphyrin-based photosensitizers are in the ultraviolet (UV) spectrum. Prolonged irradiation of living cells and tissues with UV light during the clinical application of photodynamic therapy (PDT) may cause DNA damage and cell death. Here, we report a novel persistent-luminescent nanoparticle (PLNP)-based PDT approach that uses the afterglow property of PLNPs to greatly reduce the dose of UV light while maintaining the desired cancer suppression effect. Multifunctional PLNPs coated with mesoporous silica layers and subsequently conjugated to a photosensitizer were evaluated. These nanoconjugates showed high colloidal stability and biocompatibility. Furthermore, they generated a moderate amount of O-1(2) through efficient energy transfer from the nanoparticle to the photosensitizer, which can efficiently damage cancer cells. In addition to their UV-excited luminescence, PLNPs also exhibited a long-lasting luminescence afterglow. Thus, PLNPs can serve as a persistent light source for PDT activation after excitation by an external light source is stopped. When fractionated light was used for excitation instead of continuous light at equivalent irradiation doses, confocal microscopy revealed that the photosensitizer-conjugated PLNPs showed a significantly enhanced cancer cell killing ability. Moreover, quantitative flow cytometry showed that fractionated light irradiation (60 s/100 s on/off cycle) produced up to ten times more cancer cell apoptosis/necrosis than the same dose of continuous light irradiation did. These results indicate that photosensitizer-conjugated PLNPs combined with fractionated irradiation show good potential for low-dose UV-mediated PDT activation