经教育部大学物理课程教学指导委员会批准，第十二届华东六省一市大学物理教育教学研讨会拟于2014年5月在青岛举行．会议由教育部大学物理课程教学指导委员会华东地区工作委员会主办，青岛大学承办．本次研讨会的主题为“MOOCs（Massive...经教育部大学物理课程教学指导委员会批准，第十二届华东六省一市大学物理教育教学研讨会拟于2014年5月在青岛举行．会议由教育部大学物理课程教学指导委员会华东地区工作委员会主办，青岛大学承办．本次研讨会的主题为“MOOCs（Massive Open Online Course简称，被译为“慕课”）对高等教育的影响”及传统课程的优化与适应．展开更多
Using an excitonic basis, we investigate the intraband polarization, optical absorption spectra, and terahertzemission of semiconductor superlattice with the density matrix theory. The excitonic Bloch oscillation is d...Using an excitonic basis, we investigate the intraband polarization, optical absorption spectra, and terahertzemission of semiconductor superlattice with the density matrix theory. The excitonic Bloch oscillation is driven by thedc and ac electric fields. The slow variation in the intraband polarization depends on the ac electric field frequency. Theintraband polarization increases when the ac electric field frequency is below the Bloch frequency. When the ac electricfield frequency is above the Bloch frequency, the intraband polarization downwards and its intensity decreases. Thesatellite structures in the optical absorption spectra are presented. Due to excitonic dynamic localization, the emissionlines of terahertz shift in different ac electric field and dc electric field.展开更多
The generation of terahertz （THz） emission from air plasma induced by two-color femtosecond laser pulses is studied on the basis of a transient photocurrent model. While the gas is ionized by the two-color femtoseco...The generation of terahertz （THz） emission from air plasma induced by two-color femtosecond laser pulses is studied on the basis of a transient photocurrent model. While the gas is ionized by the two-color femtosecond laser-pulses com- posed of the fundamental and its second harmonic, a non-vanishing directional photoelectron current emerges, radiating a THz electromagnetic pulse. The gas ionization processes at three different laser-pulse energies are simulated, and the corresponding THz waveforms and spectra are plotted. The results demonstrate that, by keeping the laser-pulse width and the relative phase between two pulses invariant when the laser energy is at a moderate value, the emitted THz fields are significantly enhanced with a near-linear dependence on the optical energy.展开更多
文摘经教育部大学物理课程教学指导委员会批准，第十二届华东六省一市大学物理教育教学研讨会拟于2014年5月在青岛举行．会议由教育部大学物理课程教学指导委员会华东地区工作委员会主办，青岛大学承办．本次研讨会的主题为“MOOCs（Massive Open Online Course简称，被译为“慕课”）对高等教育的影响”及传统课程的优化与适应．
基金Supported by National Science Foundation of China under Grant No.10647132the Scientific Research Fund of Hunan Provincial Education Department under Grant No.05B014
文摘Using an excitonic basis, we investigate the intraband polarization, optical absorption spectra, and terahertzemission of semiconductor superlattice with the density matrix theory. The excitonic Bloch oscillation is driven by thedc and ac electric fields. The slow variation in the intraband polarization depends on the ac electric field frequency. Theintraband polarization increases when the ac electric field frequency is below the Bloch frequency. When the ac electricfield frequency is above the Bloch frequency, the intraband polarization downwards and its intensity decreases. Thesatellite structures in the optical absorption spectra are presented. Due to excitonic dynamic localization, the emissionlines of terahertz shift in different ac electric field and dc electric field.
基金Project supported by the National Natural Science Foundation of China (Grant No.61177095)the Natural Science Foundation of Hubei Province,China(Grant No.2012FFA074)+1 种基金the Ph.D.Programs Foundation of Ministry of Education of China (Grant No.20100142110042)the Fundamental Research Funds for the Central Universities (Grant Nos.2012QN094 and 2012QN097)
文摘The generation of terahertz （THz） emission from air plasma induced by two-color femtosecond laser pulses is studied on the basis of a transient photocurrent model. While the gas is ionized by the two-color femtosecond laser-pulses com- posed of the fundamental and its second harmonic, a non-vanishing directional photoelectron current emerges, radiating a THz electromagnetic pulse. The gas ionization processes at three different laser-pulse energies are simulated, and the corresponding THz waveforms and spectra are plotted. The results demonstrate that, by keeping the laser-pulse width and the relative phase between two pulses invariant when the laser energy is at a moderate value, the emitted THz fields are significantly enhanced with a near-linear dependence on the optical energy.
