标题： 共振介导的（2+1）三光子吸收相干相位控制的脉冲带宽依赖性 显示英文标题

标题： Pulse-Bandwidth Dependence of Coherent Phase Control of Resonance-Mediated (2+1) Three-Photon Absorption

摘要： 我们详细研究了飞秒共振介导的（2+1）三光子吸收的相干相位控制及其对激发脉冲光谱带宽的依赖性。该过程处于三阶微扰弱场区域。相应的干涉机制涉及一组与中间态共振的三光子激发路径和一组近共振的三光子激发路径。本研究的模型系统为原子钠（Na），并且获得了实验和数值-理论结果。其中突出的结果是，我们发现通过简单的正确脉冲整形，增加激发带宽会导致三光子吸收相对于由变换极限脉冲诱导的吸收增强相应增加。例如，在这里，40纳米的带宽导致比变换极限吸收增强一个数量级。 显示英文摘要

摘要： We study in detail coherent phase control of femtosecond resonance-mediated (2+1) three-photon absorption and its dependence on the spectral bandwidth of the excitation pulse. The regime is the weak-field regime of third perturbative order. The corresponding interference mechanism involves a group of three-photon excitation pathways that are on resonance with the intermediate state and a group of three-photon excitation pathways that are near resonant with it. The model system of the study is atomic sodium (Na), for which experimental and numerical-theoretical results are obtained. Prominent among the results is our finding that with simple proper pulse shaping an increase in the excitation bandwidth leads to a corresponding increase in the enhancement of the three-photon absorption over the absorption induced by the (unshaped) transform-limited pulse. For example, here, a 40-nm bandwidth leads to an order-of-magnitude enhancement over the transform-limited absorption.