已为您找到该学者20条结果 成果回收站
【期刊论文】Ultrafast Electronic Excitation in CaF2 Crystals
贾天卿, Shizhen XU, Tianqing JIA, *, Xiaoxi LI, Donghai FENG, Haiyi SUN, Chengbin LI, Xiaofeng WANG, Hirao KURODA, Ruxin LI and Zhizhan XU
,-0001,():
-1年11月30日
A new pump and probe experimental system was developed, the pump pulse duration of which is stretched and is much longer than that of the probe pulse. Using this system, time-resolved electronic excitation processes and damage mechanisms in CaF2 crystals were studied. The measured reflectivity of the probe pulse begins to increase at the peak of the pump pulse and increases rapidly in the latter half of the pump pulse, when the pump pulse duration is stretched to 580 fs. Our experimental results indicate that both multiphoton ionization and impact ionization play important roles in the generation of conduction band electrons, at least they do so when the pump pulse durations are equal to or longer than 580 fs.
pump and probe setup, electronic excitation, damage mechanisms, CaF2 crystals
-
35浏览
-
0点赞
-
0收藏
-
0分享
-
42下载
-
0
-
引用
贾天卿, D.H. Fenga, Z.Z. Xu, T.Q. Jia, X.X. Li, C.B. Li, H.Y. Sun, and S.Z. Xu
Eur. Phys. J. B44, 15-20 (2005),-0001,():
-1年11月30日
Within the framework of second-order Rayleigh-Schrödinger perturbation theory, the polaronic correction to the first excited state energy of an electron in an quantum dot with anisotropic parabolic confinements is presented. Compared with isotropic confinements, anisotropic confinements will make the degeneracy of the excited states to be totally or partly lifted. On the basis of a three-dimensional Fröhlich’s Hamiltonian with anisotropic confinements, the first excited state properties in two-dimensional quantum dots as well as quantum wells and wires can also be easily obtained by taking special limits. Calculations show that the first excited polaronic effect can be considerable in small quantum dots.
-
56浏览
-
0点赞
-
0收藏
-
0分享
-
73下载
-
0
-
引用
【期刊论文】Ultrafast dynamics in ZnO thin films irradiated by femtosecond lasers
贾天卿, Chengbin Li*, Donghai Feng, Tianqing Jia, Haiyi Sun, Xiaoxi Li, Shizhen Xu, Xiaofeng Wang, Zhizhan Xu
Solid State Communications 136 (2005) 389-394,-0001,():
-1年11月30日
The damage morphologies, threshold fluences in ZnO films were studied with femtosecond laser pulses. Time-resolved reflectivity and transmissivity have been measured by the pump-probe technique at different pump fluences and wavelengths. The results indicate that two-phase transition is the dominant damage mechanism, which is similar to that in narrow band gap semiconductors. The estimated energy loss rate of conduction electrons is 1.5V/ps.
A., ZnO thin film, B., Laser processing, E., Time-resolved optical measurement, E., Electron energy loss rate
-
23浏览
-
0点赞
-
0收藏
-
0分享
-
75下载
-
0
-
引用
【期刊论文】Incoherent subharmonic light scattering in isotropic media
贾天卿, D.H. Feng∗, Z.Z. Xu, X.L. Feng, T.Q. Jia, X.X. Li, J.S. Liu
Spectrochimica Acta Part A 61 (2005) 575-578,-0001,():
-1年11月30日
Incoherent subharmonic light scattering in isotropic media is a new kind of nonlinear light scattering, which involves single input photon and multiple output photons of equal frequency. We investigate theoretically the dependence of the subharmonic scattering intensity on the hyperpolarizability of molecules and the incident intensity using nonlinear optics theory similar to that used for Hyper-Rayleigh scattering and degenerate optical parametric oscillators. It is derived that the subharmonic scattering intensities grow exponentially or superexponentially with the hyperpolarizability of molecules and the incident intensity.
Subharmonic scattering, Isotropic media, Nonlinear optics
-
21浏览
-
0点赞
-
0收藏
-
0分享
-
37下载
-
0
-
引用
【期刊论文】Mechanisms in fs-laser ablation in fused silica
贾天卿, T.Q. Jia a), Z.Z. Xu, R.X. Li, D.H. Feng, X.X. Li, C.F. Cheng, and H.Y. Sun, N.S. Xu and H.Z. Wang
,-0001,():
-1年11月30日
A theoretical model is proposed to describe the microscopic processes involved in the ablation in fused silica induced by femtosecond-laser pulse. Conduction-band electron (CBE) can absorb laser energy, the rate is calculated by quantum mechanical method and classical method. CBE is produced via photoionization (PI) and impact ionization (II). The PI and II rates are calculated by using the Keldysh theory and double-flux model, respectively. Besides the CBE production, we investigate laser energy deposition and its distribution. The equation of energy diffusion in physical space is resolved numerically. Taking energy density Edep=54 kJ/cm3 as the criterion, we calculate damage threshold, ablation depth, and ablation volumes. It is found that if energy diffusion is considered, energy density near sample surface is reduced to 1/10, damage threshold is enhanced more than 30%, ablation depth is increased by a factor of 10. Our theoretical results agree well with experimental measurements. Several ultrafast phenomena in fused silica are also discussed.
-
12浏览
-
0点赞
-
0收藏
-
0分享
-
41下载
-
0
-
引用