The influence of the carrier-envelope phase on high-harmonic generation is investigated, both experimentally and theoretically, for three different interaction gas media, driven by mid-infrared, few-cycle and CEP-stab...The influence of the carrier-envelope phase on high-harmonic generation is investigated, both experimentally and theoretically, for three different interaction gas media, driven by mid-infrared, few-cycle and CEP-stabiUzed laser pulses. Different patterns of harmonic spectra with varying CEP for the three interaction gas media are observed. Furthermore, in comparing our experiment results to the previous works driven by near-infrared laser pulses, different phenomena are found. Through numerical simulation, we find that for the two different kinds of driving fields, i.e. mid-infrared and near-infrared laser pulses, different kinds of electron trajectories contribute to the generation of high harmonics.展开更多
We investigate the plasmonic-field-enhanced high-order harmonic generation（HHG） of H atom driven by few-cycle laser pulses, by solving the time-dependent Schr？dinger equation（TDSE）. Compared with the homogeneous ...We investigate the plasmonic-field-enhanced high-order harmonic generation（HHG） of H atom driven by few-cycle laser pulses, by solving the time-dependent Schr？dinger equation（TDSE）. Compared with the homogeneous field, HHG spectra generated by inhomogeneous field exhibit two-plateau structure. We analyze the origin of the two plateaus by using the semiclassical trajectory method. Our results from both classical and TDSE simulations show that the cutoffs of the two plateaus are dramatically affected by the carrier-envelope phase（CEP） of laser pulse in the inhomogeneous field, even for a little longer pulse. Thus, we can determine the CEP of driving laser based on the cutoff position of HHG generated in the inhomogeneous field.展开更多
The spatial distribution in high-order harmonic generation（HHG） from the asymmetric diatomic molecule He H^（2＋） is investigated by numerically solving the non-Born–Oppenheimer time-dependent Schr？dinger equatio...The spatial distribution in high-order harmonic generation（HHG） from the asymmetric diatomic molecule He H^（2＋） is investigated by numerically solving the non-Born–Oppenheimer time-dependent Schr？dinger equation（TDSE）. The spatial distribution of the HHG spectra shows that there is little contribution in HHG around the geometric center of two nuclei（z = 1.17 a.u.） and the equilibrium internuclear position of the H nucleus（z = 3.11 a.u.）. We demonstrate the carrier envelope phase（CEP） effect on the spatial distribution of HHG in a few-cycle laser pulse. The HHG process is investigated by the time evolution of the electronic density distribution. The time–frequency analysis of HHG from two nuclei in HeH^（2＋） is presented to further explain the underlying physical mechanism.展开更多
An all optical method is demonstrated for measuring the carrier-envelope phase （CEP） of few-cycle laser pulses. It is found that, in the few-cycle regime, the high harmonic spectrum generated from asymmetric molecul...An all optical method is demonstrated for measuring the carrier-envelope phase （CEP） of few-cycle laser pulses. It is found that, in the few-cycle regime, the high harmonic spectrum generated from asymmetric molecules shows several half-cycle cutoffs that change their positions as the CEP varies. Such half-cycle cutoffs represent the fingerprint of different quantum trajectories and the waveform of the driving pulse. In this case, the CEP can be accurately measured from the half-cycle cutoffs.展开更多
An objective of this work is to develop a validated computational model that can be used to estimate ratcheting accumulation behavior of granular soils due to high-cyclic loading. An accumulation model was proposed to...An objective of this work is to develop a validated computational model that can be used to estimate ratcheting accumulation behavior of granular soils due to high-cyclic loading. An accumulation model was proposed to describe only the envelope of the maximum plastic deformations generated during the cyclic loading process, which can calculate the accumulated deformation by means of relatively large load cycle increments. The concept of volumetric hardening was incorporated into the model and a so-called overstress formulation was employed to describe the evolution of the accumulated volumetric deformation as a state parameter. The model accounted for ratcheting shakedown and accumulation such as a pseudo-yield surface(a shakedown surface) associated with loading inside the current virgin yield surface which was implemented into the well-known modified Cam-clay model. Finally, the model was calibrated using data from the stress-controlled drained cyclic triaxial tests on homogeneous fine grained sands. It is seen that the model can successfully represent important features of the ratcheting accumulation of both volumetric and deviatoric deformation caused by repeated drained loading over a large number of cycles.展开更多
This paper presents a Kerr-lens mode-locked Ti：sapphire laser at the repetition rate of 525 MHz, stable laser pulse as short as 10 fs with average output power of 480 mW is obtained. By injecting the pulse into photo...This paper presents a Kerr-lens mode-locked Ti：sapphire laser at the repetition rate of 525 MHz, stable laser pulse as short as 10 fs with average output power of 480 mW is obtained. By injecting the pulse into photonics crystal fibre, octave-spanning spectrum covered from 500 to 1050 nm is generated, carrier-envelope phase frequency with signal-to- noise ratio of 31dB is measured, which paves the way for the generation of a compact frequency comb.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11127901,61221064,11134010,11227902,11222439,and 11274325)the National Basic Research Program of China(Grant No.2011CB808103)the Funds from Shanghai Commission of Science and Technology(Grant No.12QA1403700)
文摘The influence of the carrier-envelope phase on high-harmonic generation is investigated, both experimentally and theoretically, for three different interaction gas media, driven by mid-infrared, few-cycle and CEP-stabiUzed laser pulses. Different patterns of harmonic spectra with varying CEP for the three interaction gas media are observed. Furthermore, in comparing our experiment results to the previous works driven by near-infrared laser pulses, different phenomena are found. Through numerical simulation, we find that for the two different kinds of driving fields, i.e. mid-infrared and near-infrared laser pulses, different kinds of electron trajectories contribute to the generation of high harmonics.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11264036,11364038,and 11465016)
文摘We investigate the plasmonic-field-enhanced high-order harmonic generation（HHG） of H atom driven by few-cycle laser pulses, by solving the time-dependent Schr？dinger equation（TDSE）. Compared with the homogeneous field, HHG spectra generated by inhomogeneous field exhibit two-plateau structure. We analyze the origin of the two plateaus by using the semiclassical trajectory method. Our results from both classical and TDSE simulations show that the cutoffs of the two plateaus are dramatically affected by the carrier-envelope phase（CEP） of laser pulse in the inhomogeneous field, even for a little longer pulse. Thus, we can determine the CEP of driving laser based on the cutoff position of HHG generated in the inhomogeneous field.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11271158,11574117,and 61575077)
文摘The spatial distribution in high-order harmonic generation（HHG） from the asymmetric diatomic molecule He H^（2＋） is investigated by numerically solving the non-Born–Oppenheimer time-dependent Schr？dinger equation（TDSE）. The spatial distribution of the HHG spectra shows that there is little contribution in HHG around the geometric center of two nuclei（z = 1.17 a.u.） and the equilibrium internuclear position of the H nucleus（z = 3.11 a.u.）. We demonstrate the carrier envelope phase（CEP） effect on the spatial distribution of HHG in a few-cycle laser pulse. The HHG process is investigated by the time evolution of the electronic density distribution. The time–frequency analysis of HHG from two nuclei in HeH^（2＋） is presented to further explain the underlying physical mechanism.
基金supported by the Key Foundation of the Ministry of Education of China(Grant No.211117)the Foundation of Hubei Co-innovation Center forUtilization of Biomass Waste,China(Grant No.XTCX004)
文摘An all optical method is demonstrated for measuring the carrier-envelope phase （CEP） of few-cycle laser pulses. It is found that, in the few-cycle regime, the high harmonic spectrum generated from asymmetric molecules shows several half-cycle cutoffs that change their positions as the CEP varies. Such half-cycle cutoffs represent the fingerprint of different quantum trajectories and the waveform of the driving pulse. In this case, the CEP can be accurately measured from the half-cycle cutoffs.
基金Projects(41302219,41302076)supported by the National Natural Science Foundation of China
文摘An objective of this work is to develop a validated computational model that can be used to estimate ratcheting accumulation behavior of granular soils due to high-cyclic loading. An accumulation model was proposed to describe only the envelope of the maximum plastic deformations generated during the cyclic loading process, which can calculate the accumulated deformation by means of relatively large load cycle increments. The concept of volumetric hardening was incorporated into the model and a so-called overstress formulation was employed to describe the evolution of the accumulated volumetric deformation as a state parameter. The model accounted for ratcheting shakedown and accumulation such as a pseudo-yield surface(a shakedown surface) associated with loading inside the current virgin yield surface which was implemented into the well-known modified Cam-clay model. Finally, the model was calibrated using data from the stress-controlled drained cyclic triaxial tests on homogeneous fine grained sands. It is seen that the model can successfully represent important features of the ratcheting accumulation of both volumetric and deviatoric deformation caused by repeated drained loading over a large number of cycles.
基金supported by National Natural Science Foundation of China (Grant Nos 60490281 and 60621063)National Basic Research Program of China (Grant No 2007CB815104)
文摘This paper presents a Kerr-lens mode-locked Ti：sapphire laser at the repetition rate of 525 MHz, stable laser pulse as short as 10 fs with average output power of 480 mW is obtained. By injecting the pulse into photonics crystal fibre, octave-spanning spectrum covered from 500 to 1050 nm is generated, carrier-envelope phase frequency with signal-to- noise ratio of 31dB is measured, which paves the way for the generation of a compact frequency comb.
