Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences
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Demonstration of a diode pumped Nd,Y co-doped SrF2 crystal based, high energy chirped pulse amplification laser system
No full textShanghai Sailing Program [15YF1413500]; National Natural Science Foundation of China (NSFC) [11127901, 11134010, 61422511, 51432007]We report, to the best of our knowledge, a chirped pulse amplification laser system based on the Nd,Y:SrF2 crystal for the first time. The incorporation of Y3+ nonactive ions can significantly improve laser properties of Nd:SrF2 crystal, including broader emission linewidth, larger cross-section as well as longer fluorescence lifetime. Pulse laser with 5.1 mJ (uncompressed), 3.7 mJ (compressed) energy, 1.6 ps duration at 5 Hz repetition rate is demonstrated. The results indicate that the Nd,Y:SrF2 crystal is a potential candidate with excellent laser and thermal performance for developing ultra-intense laser with high repetition rate. (C) 2016 Elsevier B.V. All rights reserved
Design and simulation of a single-cycle source tunable from 2 to 10 micrometers
No full text100 Talents Program of CAS; National Natural Science Foundation of China [61475169, 61521093, 11127901]; Youth Innovation Promotion Association of CAS; Strategic Priority Research Program of the Chinese Academy of Sciences [XDB16]; International S&T Cooperation Program of China [2016YFE0119300]We present the design of a novel single-cycle infrared source tunable from 2 to 10 lam. We simulate the optical parametric amplification (OPA) in BBO and the difference frequency generation (DFG) in AGS based on coupled second-order three-wave nonlinear propagation equations. We combine this with the unidirectional pulse propagation equation, which models the generation of the initial supercontinuum seed in sapphire and the final self compression in YAG, ZnS, and GaAs, respectively. The obtained results indicate that single cycle pulses can be produced in a tunable range of 2 to 10 lam. (C) 2017 Optical Society of Americ
Dissociative ionization of CH2Br2 in 800 and 400 nm femtosecond laser fields
No full textNational Natural Science Fund [11604046, 11474096]; Natural Science Foundation of Shanghai [16ZR1448100]; Chenguang Program; Shanghai Education Development Foundation; Shanghai Municipal Education Commission [16CG38]; Shanghai-International Scientific Cooperation Fund [16520721200]We experimentally demonstrate the dissociative ionization of CH2Br2 molecules irritated by 800 and 400 nm femtosecond laser fields using time-of-flight mass spectra and dc-sliced ion imaging technology. Our results show that in both laser fields, CH2Br2 can ionize to CH2Br2+, then CH2Br2+ break one C-Br bond to produce fragments CH2Br(+) and Br(+). The charge assignment is determined by the ionization energy of the fragments. Additionally, in 400 nm laser fields, the CH2Br2+ can overpass a transition state to form an intermediate CH2Br-Br+, then the intermediate break C-Br bond to produce Br-2 or Br-2(+) via elimination channel
Effective mass dependence in laser-induced absorption of ZnO pumped by mid-infrared laser pulse
No full textNational Natural Science Foundation of China [11127901, 61221064, 11134010, 11227902, 11222439, 11274325]; 973 Project [2011CB808103]The time-resolved laser-induced absorption below the band edge in a ZnO sample is observed in the presence of a strong mid-infrared (MIR) pulse. The laser-induced absorption increases with the pump intensity, but it is different in two directions ([1100] and [1120] direction). The simulation results demonstrate that this phenomenon is primarily caused by the direction dependence of the reduced effective mass of electron and hole. For smaller reduced effective mass, the number of multi-photon ionization channel becomes larger, the probe photons are more likely to be absorbed and the absorption coefficients is larger, so lower pump intensity is needed for absorption saturation. (C) 2015 Elsevier B.V. All rights reserved
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
Isolated attosecond pulse generation with few-cycle two-color counter-rotating circularly polarized laser pulses
No full textNational Natural Science Foundation of China [61690223, 11561121002, 61521093, 11227902, 11404356, 11574332]; Strategic Priority Research Program of the Chinese Academy of Sciences [XDB16]Most of the schemes for generating isolated attosecond pulses (IAP) are sensitive to the carrier-envelope phase (CEP) of the driving lasers. We propose a scheme for generating IAP using two-color counter-rotating circularly polarized (TCCRCP) laser pulses. The results demonstrate that the dependence of the IAP generation on CEP stability is largely reduced in this scheme. IAP can be generated at most of CEPs. Therefore, the experiment requirements become lower
Moving toward optoelectronic logic circuits for visible light: a chalcogenide glass single-mode single-polarization optical waveguide switch
No full textNational Natural Science Foundation of China (NSFC) [11374316]In this paper, we propose an arsenic trisulfide (As-S) optical waveguide switch-based logic gate mainly comprised of a photorefractive Sn1As20S79 waveguide core and a LiNbO3 crystal substrate. In combination with the unique optical stopping effect of Sn1As20S79, this device can realize logical operations on an electrical signal and an optical signal, holding promises to be applied in optoelectronic logic circuits. While most of the previous research on As-S has focused on applications in the infrared regime, this device operates at the visible wavelengths of 632.8 and 441.6 nm, which are the specific wavelengths for optical stopping. As the kernel part of this logic gate, an optical waveguide switch based on an electro-optic coupler is employed to control optical signals by electrical signals, providing a solid foundation of operation for an electro-optic logic function. Some crucial design specifications of the switch are optimized by means of simulation analysis. It is found that less than 10 V of applied voltage is sufficient to realize a satisfactory function of the switch. A coupling efficiency of 90% and an extinction ratio of greater than 10 dB are achieved by simulating the lightwave propagation in the waveguide switch. Since the waveguide structure of the switch has no upper cladding, it is different from that of a ridge waveguide or a buried waveguide, and is, thus, convenient to fabricate by only using UV exposure without etching. Our work will open new possibilities for photoelectric hybrid logical operation in visible light, and, thus, provide fertile ground for applications in programmable optical chips. (C) 2017 Optical Society of Americ
Next Generation Driver for Attosecond and Laser-plasma Physics
No full textDFG [Transregio TR18]; Munich Centre for Advanced Photonics (MAP); Laserlab-Europe [284464]; Euratom research and training programme within EUROfusion Consortium [633053]The observation and manipulation of electron dynamics in matter call for attosecond light pulses, routinely available from high-order harmonic generation driven by few-femtosecond lasers. However, the energy limitation of these lasers supports only weak sources and correspondingly linear attosecond studies. Here we report on an optical parametric synthesizer designed for nonlinear attosecond optics and relativistic laser-plasma physics. This synthesizer uniquely combines ultra-relativistic focused intensities of about 10(20)W/cm(2) with a pulse duration of sub-two carrier-wave cycles. The coherent combination of two sequentially amplified and complementary spectral ranges yields sub-5-fs pulses with multi-TW peak power. The application of this source allows the generation of a broad spectral continuum at 100-eV photon energy in gases as well as high-order harmonics in relativistic plasmas. Unprecedented spatio-temporal confinement of light now permits the investigation of electric-field-driven electron phenomena in the relativistic regime and ultimately the rise of next-generation intense isolated attosecond sources
Observation of polariton resonances with five-level M-type atoms in an optical cavity
No full textNational Natural Science Foundation of China [91321101, 11274112, 11474092]We study the polariton resonances with the five-level M-type atoms inside an optical cavity through the observation of the cavity transmission spectrum. The ultranarrow peaks associated with the dark-state polaritons in the system can be achieved by adjusting three coupling fields. Simple theory analysis and numerical simulations are also presented. (C) 2017 Published by Elsevier B.V