报告题目： Ultrabroad terahertz spectrum irradiated by 800nm femtosecond filaments in gases

报 告 人： Dr. Olga Kosareva

Physics Faculty & International Laser Center

Lomonosov Moscow State University

主 持 人：徐淮良 教授

报告时间：2015年8月18日10:00

报告地点：唐敖庆楼D314报告厅

主办单位：电子科学与工程学院

集成光电子学国家重点联合实验室

O.G. Kosareva defended her PhD in 1995 at International Laser Center of Lomonosov Moscow State University. She is a leading world-recognized scientist in the field of femtosecond laser pulse propagation in transparent media. She was the first one who developed the model and the computer code to describe the self-consistent physical picture of femtosecond laser pulse filamentation in air and the accompanying phenomena. She demonstrated the dynamic scenario of multiple filamentation of high power femtosecond laser radiation in the atmosphere and proved birefringence induced in the high-intensity zone of the filament. In the year 2012 she got the highest scientific qualification in Russia, that is State Doctor of Physics and Math Sciences. Her current interests is the development of the efficient terahertz radiation source, which can be the air-based plasma or excited neutral molecules produced by extended filaments in air and/or a wire laser based on quantum cascade transitions.

Abstract: Femtosecond pulse filamentation represents a string of the localized laser pulse energy persisting over long propagation distances. Because of the high intensity in the filament (~100 TW/cm2) a number of nonlinear processes take place along the propagation. The nonlinearity enhanced in the extended filament results in the emergence of both continuum of frequencies and quasi-isolated pulses in certain spectral ranges. We have fully studied the long-wavelength part of 800 nm filament spectral continuum (0.8 < l < 3000 mm) and identified new physical mechanisms supporting experimentally the observed phenomena such as 3d raman light bullet in the near-infrared range, single-cycle mir pulse generation and enhancement, ring-type shape of the spatial distribution of terahertz radiation from the air-based plasma. we disclosed a long-term debate and revealed the relationship between the two major physical mechanisms, namely free and bound electrons, which induce the broadband terahertz spectrum generation in the two-color filament plasma