Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences
Not a member yet
13355 research outputs found
Sort by
Generation of ultra-intense gamma-ray train by QED harmonics
No full textMinistry of Science and Technology [2011CB808104]; National Natural Science Foundation of China [61221064, 11374319, 11125526, 11335013, 11127901]In nonlinear media, photons may combine into a photon of energy and momentum of all those photons. This process, called harmonic generation, happens in nonlinear crystal, gas, and relativistic plasma. When the laser intensity reaches 10 22 W/cm(2), QED effects appear and play a significant role in the harmonic generation. In contrast to the gas and relativistic high-order harmonic generation processes, harmonics influenced by QED effects are usually not coherent because of the characteristic of random radiation, while the property of high intensity and ultra-short duration is conserved. In this work, the generation of high-order harmonics with QED effects is investigated by one-and two-dimensional particle-in-cell simulations. Studies have shown that interacting with a laser pulse with the intensity of I = 5: 35 x 10(23) W/cm(2), such harmonics can produce ultra-short gamma-ray train with periodic structures. The period of gamma-ray train is half of the laser period, and the peak intensity is 1: 4 x 10(22) W/cm(2) from one-dimensional simulation when ions are considered immobile. This new harmonic production with QED effects are crucial to light-matter interaction in strong field and can be verified in experiments by 10 PW laser facilities in the near future. Published by AIP Publishing
High power TEM00 picosecond output based on a Nd:GdVO4 discrete path Innoslab amplifier
No full textNational Natural Science Foundation of China (NSFC) [11504394, 61521093, 61378030]We propose a technique for eliminating self-lasing and suppressing amplified spontaneous emission in a partially pumped slab amplifier with a discrete path configuration. High gain character and homogeneous gain distribution were well preserved with the proposed scheme. Based on the Nd:GdVO4 crystal, a 99W, 12.4 ps TEM00 laser output was achieved with a 42% extraction efficiency. The diffraction limited beam quality remained undisturbed after amplification with M-x(2) = 1.09 and M-y(2) = 1.07 in the orthogonal directions. (C) 2016 Optical Society of Americ
Parallel Phase Modulation Algorithm Based Spectral Phase Measurement and Compensation
No full text详细探究了平行相位调制(PPM)算法在飞秒激光脉冲的频谱相位测量与补偿中的应用。通过数值模拟讨论了调制频率选取和相位复原问题。基于该算法搭建了一套飞秒激光脉冲整形装置,使用自行编写的LabVIEW程序完成频谱相位的测量补偿过程,并使用多光子脉冲内干涉相位扫描(MIIPS)方法验证了实验结果的准确性。不同于MIIPS等已有超快激光脉冲测量方法,PPM法无需测量非线性信号的光谱,只需测量信号强度即可快速确定频谱相位。国家自然科学基金The parallel phase modulation (PPM) algorithm is investigated for spectral phase measurement and compensation. Detailed theoretical analysis and a numerical simulation are carried out to find how to determine the modulation frequency and reconstruct the spectral phase. A femtosecond pulse shaper is set up based on the PPM algorithm. The shaper is driven by our home-developed LabVIEW program and can be used to measure and compensate spectral phase of femtosecond pulses. The experimental results are verified with the multi-photon intra-pulse interference phase scan (MIIPS) method. Different from such existing ultrafast pulse measurement methods as MIIPS, the PPM method only needs to measure the signal intensity to determine the spectral phase quickly, and requires no spectrum measurements of nonlinear signals
Phase-Matched Second-Harmonic Generation in an On-Chip LiNbO3 Microresonator
No full textNational Basic Research Program of China [2014CB921300]; NSFC [61275205, 11174305, 61405220, 61505231]; Fundamental Research Funds for the Central UniversitiesThe realization of an efficient nonlinear parametric process in microresonators is a challenging issue largely because of an inherent difficulty in simultaneously ensuring the phase-matching condition and a coherent multiple-resonance condition for all the waves participating in the nonlinear conversion process. Here, we demonstrate highly efficient second-harmonic generation in an on-chip LiNbO3 microresonator fabricated by femtosecond-laser direct writing. We overcome the above difficulty by selectively exciting high-order modes in the fabricated thin-disk microresonator. Thanks to the low optical absorption and high nonlinear optical coefficient of LiNbO3 crystal, we achieve a normalized conversion efficiency of 1.106 x 10(-3)/mW in the on-chip LiNbO3 microdisk with a diameter of approximately 102 mu m
Proton beam shaped by "particle lens" formed by laser-driven hot electrons
No full textNational Natural Science Foundation of China [11335013, 11125526, 11575274, 11305236, 61221064]; Shanghai Natural Science Foundation [13ZR1463300]Two-dimensional tailoring of a proton beam is realized by a "particle lens" in our experiment. A large quantity of electrons, generated by an intense femtosecond laser irradiating a polymer target, produces an electric field strong enough to change the trajectory and distribution of energetic protons flying through the electron area. The experiment shows that a strip pattern of the proton beam appears when hot electrons initially converge inside the plastic plate. Then the shape of the proton beam changes to a "fountain-like" pattern when these hot electrons diffuse after propagating a distance. Published by AIP Publishing
Stress-state manipulation in fused silica via femtosecond laser irradiation
No full textEuropean Research Council (ERC) [ERC-2012-StG-307442]; Science and Technology Facilities Council (STFC) [ST/H005595/1]; Richemont International; National Basic Research Program of China [2014CB921300]Controlling the stress in glass after laser exposure is of prime importance not only for photonics applications, but also for preserving the mechanical integrity of glass components in general. The sub-surface exposure of fused silica to femtosecond laser pulses can induce a permanent and localized modification to the glass structure. In this work, we present evidence that femtosecond laser exposure can be used to continuously tailor the stress in the material, from a tensile to compressive state, as the laser pulse energy is changed. In addition, we demonstrate that this effect can not only be obtained while transitioning between different laser-induced microstructures, but also at low pulse energy, in the laser exposure regime particularly relevant for fabricating waveguides. These results demonstrate that femtosecond laser exposure is a versatile tool for fully controlling the stress landscape in a volume of silica, opening up new technological opportunities, like for instance, direct write stress-free waveguides, direct-write stress-induced birefringence state or mechanically reinforced parts, by locally preloading it. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License
阿秒科学前沿开拓与强场量子相干控制研究
No full text该研究产生更短脉宽、更高光子能量与更高亮度的阿秒相干光源以及原子分子中阿秒电子波包的探测和控制,预期目标主要包括:(1)实现亚飞秒时间尺度和原子级空间尺度内实时观测和控制电子动力学行为;(2)在多电子弛豫过程中,电子重排、电子-电子碰撞动力学等多电子复杂动力学研究中取得若干突破;(3)揭示有重要意义的化学反应的电子动力学物理本质。探索阿秒脉冲作用下物质的电子动力学新规律及其应用。开展中红外激光与气体介质相互作用产生高次谐波的实验和理论研究,采用双色场方法获得高次谐波连续谱,为进一步将阿秒脉冲宽度测量和光
Electromagnetically induced transparency in a Zeeman-sublevels Lambda-system of cold Rb-87 atoms in free space
No full textNational Basic Research Program of China [2011CB921504]; National Natural Science Foundation of China [91536107]We report the experimental investigation of electromagnetically induced transparency (EIT) in a Zeeman-sublevels L -type system of cold Rb-87 atoms in free space. We use the Zeeman substates of the hyperfine energy states 5(2)S(1/2), F = 2 and 5(2)P(3/2), F' = 2 of Rb-87 D-2 line to form a Lambda-type EIT scheme. The EIT signal is obtained by scanning the probe light over 1 MHz in 4 ms with an 80 MHz arbitrary waveform generator. More than 97% transparency and 100 kHz EIT window are observed. This EIT scheme is suited for an application of pulsed coherent storage atom clock
Fifteen years of coldmatter on the atom chip: promise, realizations, and prospects
No full textIsrael Science Foundation; EC 'MatterWave' consortium [FP7-ICT-601180]; German DFG through the DIP program [FO 703/2-1]; PBC program for outstanding postdoctoral researchers of the Israeli Council for Higher Education; Ministry of Immigrant Absorption (IsHere we review the field of atom chips in the context of Bose-Einstein Condensates (BEC) as well as cold matter in general. Twenty years after the first realization of the BEC and 15 years after the realization of the atom chip, the latter has been found to enable extraordinary feats: from producing BECs at a rate of several per second, through the realization of matter-wave interferometry, and all the way to novel probing of surfaces and new forces. In addition, technological applications are also being intensively pursued. This review will describe these developments and more, including new ideas which have not yet been realized