论文标题
尺寸控制的量子点揭示了人体内过渡对固体高阶谐波产生的影响
Size-controlled quantum dots reveal the impact of intraband transitions on high-order harmonic generation in solids
论文作者
论文摘要
自从固体中发现高阶谐波产生（HHG）以来，已经努力理解其生成机制，并且已知带有频带和内的过渡是必不可少的。但是，内标的过渡受固体的电子结构的影响，以及它们如何促进非线性载体的产生，而HHG仍然是一个空旷的问题。在这里，我们使用中红外激光脉冲在CDSE和CDS量子点（QD）中研究HHG，其中量子限制可用于控制内映射过渡。我们发现，当平均QD尺寸从约2 nm增加到3 nm时，每个激发体积的HHG强度和产生的载体密度都会增加。我们表明，较大QD中子带隙能的降低会增强对象的过渡，这反过来又通过与带间跃迁耦合来增加光载副注入的速率，从而增强了HHG。
Since the discovery of high-order harmonic generation (HHG) in solids, much effort has been devoted to understanding its generation mechanism and both interband and intraband transitions are known to be essential. However, intraband transitions are affected by the electronic structure of a solid, and how they contribute to nonlinear carrier generation and HHG remains an open question. Here, we use mid-infrared laser pulses to study HHG in CdSe and CdS quantum dots (QDs), where quantum confinement can be used to control the intraband transitions. We find that both the HHG intensity per excited volume and the generated carrier density increase when the average QD size is increased from about 2 nm to 3 nm. We show that the reduction of the subband gap energy in larger QDs enhances intraband transitions, and this in turn increases the rate of photocarrier injection by coupling with interband transitions, resulting in enhanced HHG.
