Nonlinear dichroism in double ionization of He by an intense elliptically-polarized few-cycle XUV pulse

Prof. Anthony F. Starace

University of Nebraska, Lincoln, USA

地点: 物理楼南506教室

时间: 11月6日 (星期四) 下午2:30--3:30

Control of double ionization of He by means of the polarization and carrier-envelope-phase (CEP) of an intense, few-cycle attosecond XUV pulse is demonstrated numerically by solving the six-dimensional two-electron, time-dependent Schr?dinger equation for He interacting with an elliptically-polarized XUV pulse. A new nonlinear dichroic effect is predicted. Guided by perturbation theory, we predict the existence of a new nonlinear dichroic effect that is sensitive to the CEP, ellipticity, peak intensity, and temporal duration of a few-cycle, elliptically-polarized XUV attosecond pulse. This dichroic effect (i.e., the difference of the two-electron angular distributions for opposite helicities of the ionizing XUV pulse) originates from interference of first- and second-order perturbation theory amplitudes, allowing one to probe and control S- and D-wave channels of the two-electron continuum. Our results show that this nonlinear dichroism is highly sensitive to the pulse CEP. Accordingly, by tuning the CEP one can vary the relative contributions to the total nonlinear dichroism of different perturbation theory amplitudes, thereby allowing one to determine their relative magnitudes.

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