论文标题
在“水窗”范围内通过光学着装氢等离子体的C5+ X射线激光器的脉冲形成
Attosecond pulse formation in the "water window" range by optically dressed hydrogen-like plasma-based C5+ X-ray laser
论文作者
论文摘要
在本文中，我们通过在“水窗”范围内在3.4 nm波长下以3.4 nm波长的光学调制来介绍Attosent脉冲形成的分析理论，考虑到由上激光态的辐射衰减引起的种群反演的变化。我们为X射线激光器扩增具有时间依赖性种群反转的X射线场的分析解，该激光器同时被强光激光场辐照，并使用它来找到从窄带X射线播种场上从狭窄的脉冲形成的最佳条件。我们表明，通过通过使用谐振介质（X射线激光的活性介质）进行脉冲形成，可以通过放大X射线场的谐振光谱分量的外部衰减来改善脉冲的形状，以减小脉冲峰强度（i）的成本（I）或（ii）。分析理论的结果与Maxwell-Bloch方程的数值解决方案非常一致，该方程的数值解考虑了活性培养基的非线性以及放大的自发发射。在分析和数值上，我们都表明，在“水窗”范围内的载波波长3.4 nm处，在载体波长3.4 nm处生产以低于200的脉冲和峰值强度超过10^12 w/cm^2的可能性，这使它们对生物学和医疗应用有吸引力。
In this paper, we present the analytical theory of attosecond pulse formation via optical modulation of an active medium of the hydrogen-like C5+ plasma-based X-ray laser at 3.4 nm wavelength in the "water window" range, taking into account a variation of the population inversion caused by radiative decay of the upper lasing states. We derive an analytical solution for the X-ray field amplified by an X-ray laser with time-dependent population inversion, which is simultaneously irradiated by a strong optical laser field, and use it to find the optimal conditions for the attosecond pulse formation from a narrowband seeding X-ray field. We show that the shape of pulses can be improved at the cost of reduced pulse peak intensity (i) via external attenuation of the resonant spectral component of the amplified X-ray field or (ii) by using a resonantly absorbing medium (the active medium of the X-ray laser after the change of sign of the population inversion) for the pulse formation. The results of the analytical theory are in a good agreement with the numerical solutions of the Maxwell-Bloch equations which account for the nonlinearity, as well as the amplified spontaneous emission, of the active medium. Both analytically and numerically we show the possibility to produce a train of attosecond pulses with sub-200 as duration and the peak intensity exceeding 10^12 W/cm^2 at the carrier wavelength 3.4 nm in the "water window" range, which makes them attractive for the biological and medical applications.
