Within the framework of plane-wave angular spectrum analysis of the electromagnetic field structure, a solution valid for tightly focused radially polarized few-cycle laser pulses propagating in vacuum is presented. T...Within the framework of plane-wave angular spectrum analysis of the electromagnetic field structure, a solution valid for tightly focused radially polarized few-cycle laser pulses propagating in vacuum is presented. The resulting field distribution is significantly different from that based on the paraxial approximation for pulses with either small or large beam diameters. We compare the electron accelerations obtained with the two solutions and find that the energy gain obtained with our new solution is usually much larger than that with the paraxial approximation solution.展开更多
This paper reports the carrier-envelop phase (CEP) locking for the 5 fs re-compressed laser pulse generated from a chirped pulse amplified (CPA) Ti:sapphire laser at 1 kHz repetition rate. A phase locking feedback sys...This paper reports the carrier-envelop phase (CEP) locking for the 5 fs re-compressed laser pulse generated from a chirped pulse amplified (CPA) Ti:sapphire laser at 1 kHz repetition rate. A phase locking feedback system with two loops was designed to control the fast fluctuation arising from the seeding laser and the slow fluctuation arising from the sub-mJ amplified pulse. The principle and structure of the phase control system, including the CEP detection, servo loop design and phase locking result, are analyzed. The experiment shows that our phase locking system can be well used to establish the stable phase locking of few-cycle amplified laser pulse, and the CEP variation of below 53 mrad (rms) was demonstrated during a locking period of more than 3 h.展开更多
We numerically study the pulse compression approaches based on atomic or molecular gases in a hollow-core fiber.From the perspective of self-phase modulation（SPM）, we give the extensive study of the SPM influence on...We numerically study the pulse compression approaches based on atomic or molecular gases in a hollow-core fiber.From the perspective of self-phase modulation（SPM）, we give the extensive study of the SPM influence on a probe pulse with molecular phase modulation（MPM） effect. By comparing the two compression methods, we summarize their advantages and drawbacks to obtain the few-cycle pulses with micro- or millijoule energies. It is also shown that the double pump-probe approach can be used as a tunable dual-color source by adjusting the time delay between pump and probe pulses to proper values.展开更多
The asymmetric photoionization of atoms irradiated by intense, few-cycle laser pulses is studied numerically. The results show that the pulse intensity affects the asymmetric photoionization in three aspects. First, a...The asymmetric photoionization of atoms irradiated by intense, few-cycle laser pulses is studied numerically. The results show that the pulse intensity affects the asymmetric photoionization in three aspects. First, at higher intensities, the asymmetry becomes distinctive for few-cycle pulses of longer durations. Second, as the laser intensity increases, the maximal asymmetry first decreases then increases after it has reached a minimal value. Last, the value of the carrier-envelope phase corresponding to the maximal asymmetry varies with the pulse intensity. This study reveals that the increasing of pulse intensity is helpful for observing the asymmetric photoionization.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.10734130,10935002,and 11075105)the National Basic Research Program of China (Grant No.2009GB105002)
文摘Within the framework of plane-wave angular spectrum analysis of the electromagnetic field structure, a solution valid for tightly focused radially polarized few-cycle laser pulses propagating in vacuum is presented. The resulting field distribution is significantly different from that based on the paraxial approximation for pulses with either small or large beam diameters. We compare the electron accelerations obtained with the two solutions and find that the energy gain obtained with our new solution is usually much larger than that with the paraxial approximation solution.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 60490281, 60621063 and 60608003)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KJCX-SW-W14)the National Basic Research Program of China (Grant No. 2007CB815104)
文摘This paper reports the carrier-envelop phase (CEP) locking for the 5 fs re-compressed laser pulse generated from a chirped pulse amplified (CPA) Ti:sapphire laser at 1 kHz repetition rate. A phase locking feedback system with two loops was designed to control the fast fluctuation arising from the seeding laser and the slow fluctuation arising from the sub-mJ amplified pulse. The principle and structure of the phase control system, including the CEP detection, servo loop design and phase locking result, are analyzed. The experiment shows that our phase locking system can be well used to establish the stable phase locking of few-cycle amplified laser pulse, and the CEP variation of below 53 mrad (rms) was demonstrated during a locking period of more than 3 h.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11204328,61221064,61078037,11127901,11134010,and 61205208)the National Basic Research Program of China(Grant No.2011CB808101)the Natural Science Foundation of Shanghai,China(Grant No.13ZR1414800)
文摘We numerically study the pulse compression approaches based on atomic or molecular gases in a hollow-core fiber.From the perspective of self-phase modulation（SPM）, we give the extensive study of the SPM influence on a probe pulse with molecular phase modulation（MPM） effect. By comparing the two compression methods, we summarize their advantages and drawbacks to obtain the few-cycle pulses with micro- or millijoule energies. It is also shown that the double pump-probe approach can be used as a tunable dual-color source by adjusting the time delay between pump and probe pulses to proper values.
基金supported by the National Natural Science Foundation of China (Grant Nos 60408008 and 10774153)the Natural Science Key Foundation of Shanghai (Grant No 04JC14036)+1 种基金the National Basic Research Program of China (Grant No 2006CD806000)the Rising Star Program of Shanghai,China (Grant No 08QH1402400)
文摘The asymmetric photoionization of atoms irradiated by intense, few-cycle laser pulses is studied numerically. The results show that the pulse intensity affects the asymmetric photoionization in three aspects. First, at higher intensities, the asymmetry becomes distinctive for few-cycle pulses of longer durations. Second, as the laser intensity increases, the maximal asymmetry first decreases then increases after it has reached a minimal value. Last, the value of the carrier-envelope phase corresponding to the maximal asymmetry varies with the pulse intensity. This study reveals that the increasing of pulse intensity is helpful for observing the asymmetric photoionization.
