摘要：
The dependence of the wave packet process of three-level ladder K2 molecules on pulse width was investigated via time-dependent wave packet method, and was firstly quantified. There is no Autler-Townes splitting in the photoelectron spectrum with weaker pump intensity or shorter pulse width. The oscillation period of wave packet increases and the oscillation amplitude decreases with increasing pulse width. The pulse width affects Rabi oscillation, which results in the periodical change of the populations of the electronic state. Quantifying its effect on the population of the excited state shows that the change frequency varies with increasing pump intensity. The results illustrates that the needed population in electronic state of interested can be obtained by controlling pulse width, which provide some important basis for light manipulation of molecular processes experimentally.
作者机构：
[袁志; 朱卫华; 王新林; 陈志勇; 郭玮; 刘辉] School of Electrical Engineering, University of South China, Hengyang, Hunan, China;[王新林] School of Mechanical Engineering, University of South China, Hengyang, Hunan, China
通讯机构：
[Wang, X.-L.] S;School of Electrical Engineering, University of South China, Hengyang, Hunan, China
关键词：
亚波长金属孔阵列;增强光透射;时域有限差分;单元结构对称性;表面等离激元
摘要：
采用三维时域有限差分方法,对比研究了石英基底上周期性亚波长圆形、纽扣形、半圆形和太极形四种具有不同对称性的孔阵列微结构金属膜的增强光透射特性,并分别探讨了阵列周期、小孔尺寸对这四种阵列结构透射特性的影响.结果表明增强光透射特性对单元结构对称性具有很强的依赖性：在超短高斯光脉冲激励下,随着单元结构对称性的降低,归一化透过率逐渐增大,红外波段的透射峰发生大量红移,且其与可见光波段的透射峰之间的距离逐渐增大,在对称性破缺的太极形孔阵列中两峰间距最大,可达1 300 nm左右.表面等离激元模式与局域表面等离子体共振模式在增强光透射现象中起着重要的作用.在可见光波段,表面等离激元模式是这四种阵列结构的光透射增强的主导性因素;在红外波段,局域表面等离子体共振模式对单元结构对称性较差孔阵列结构的增强光透射特性有着显著影响. 3D finite-difference time-domain method was employed to comparatively study the enhanced optical transmission of four kinds of periodic subwavelength hole arrays metallic films,such as circular-shaped,button-shaped,semicircular-shaped and Tai-Chi-shaped holes which had different symmetries and were deposited on a quartz substrate. The effect of the hole arrays periodicity and the hole size on the enhanced optical transmission of these four array structures were investigated. The results show that the enhanced optical transmission is strongly dependent on the symmetries of unit cells. Under the excitation of ultrashort Gauss light pulse,the normalized transmission increases gradually with the reduction of unit structural symmetries,the transmission peak in infrared wavelengths range undergoes a large spectral red-shift. The distance between the transmission peak in visible and infrared wavelengths range increases gradually. The largest distance of 1 300 nm is in symmetry breaking Tai-Chi-shaped arrays. The surface plasmon polaritons mode and the localized surface plasmon resonance mode play important roles in the process of the enhanced optical transmission. In visible wavelengths,the surface plasmonic polaritons mode is the dominant factor to the enhanced optical transmission of these four arrays structures. In infrared wavelengths,the localized surface plasmon resonance mode significantly affects the enhanced optical transmission of the hoel arrays in poor unit symmetries.
摘要：
We theoretically investigate the Autler-Townes (AT) splitting in the photoelectron spectra of threelevel ladder K2 molecule driven by a pump-probe pulse via employing the time-dependent wave packet approach. The effect of the pump/probe laser intensity and wavelength on AT splitting is detailed studied. The magnitude of AT splitting increases with increasing the pump laser intensity, but does not vary with probe intensity. The double splitting with asymmetric profiles arises due to the nonresonant excitation. The double structure is transformed into one peak progressively as the pump is detuned from the resonance wavelength, which can be explained in terms of the asymmetric excitation/population of dressed states. The splitting between AT doublet changes with pump wavelength, but does not change with probe wavelength. The double peaks shift to lower energy with the different shift with increasing pump wavelength, but with the same shift with probe wavelength.
摘要：
煤矿井下人员定位系统种类千变万化，但主要是在硬件和软件上的差异，因此，选择合适的硬件结构和软件架构会有效地避免井下巷道复杂，环境恶劣，干扰严重等因素.本文设计的基于NXP最新推出的集成片上TOF引擎的JN5168无线微控制器的井下人员定位前端控制系统，支持IEEE802.15.4无线通信协议，只需要设计芯片正常工作必要的外围电路，再通过改进TOF ( Time of Flight)测距软件定位算法，便可构成一个精确定位系统.该系统满足成本低、开发时间短、定位误差低、功耗低、实时性快等优点，对煤矿井下复杂环境的人员定位系统的研制具有一定的理论和应用价值.
摘要：
Finite-difference time-domain (FDTD) method is employed to study the optical properties of a novel kind of periodic subwavelength hole arrays composed of Tai-chi-shaped holes in silver film, and the optical transmission properties of femtosecond optical pulse excitation is numerically calculated. We find that this Tai-chi-shaped device has better optical band-pass filtering properties, such as narrower pass band and higher transmissivity in visible wavelengths range, than other devices under consideration. Based on the generation of surface plasmons resonance mode in the dielectric-metal interface, the center wavelength of transmission can be tuned by changing the array periodicities. We observe that the tune ability mainly depends on the space period along the direction parallel to that of the incident pulse polarization. It is also found that both the strength and the wavelength of the transmission peaks of rectangularly distributed metal hole arrays are determined by the polarization of incident light. Additionally, we demonstrate the typical band-pass filtering properties of this Tai-Chi-shaped holes structure. The full-width at half-maximum (FWHM) of the narrow pass band is about 20 nm in visible wavelengths range. (C) 2014 Elsevier B.V. All rights reserved.
