Efficient metallic spintronic emitters of ultrabroadband terahertz radiation
Efficient metallic spintronic emitters of ultrabroadband terahertz radiation
复制标题
DOI：
10.1038/nphoton.2016.91
复制
发表时间：
2016-07-01
期刊：
影响因子：
35
通讯作者：
Kampfrath, T.
中科院分区：
文献类型：
--
作者：
Seifert, T.;Jaiswal, S.;Kampfrath, T.
太赫兹电磁辐射在许多应用中都非常有用，包括成像和光谱学。因此，非常希望有一个有效的桌面发射器覆盖1-30太赫兹窗口，由低成本，低功率飞秒激光振荡器驱动。到目前为止，所有的固态发射器都只利用与电子电荷有关的物理原理，并提供具有较大间隙的发射光谱。在这里，我们利用电子自旋来实现一个概念上的新太赫兹源，它依赖于磁性金属多层中的三种定制的基本自旋电子和光子现象：超快光诱导自旋电流，逆自旋霍尔效应和宽带法布里-佩罗共振。在分析模型的指导下，这种自旋电子路径为系统优化提供了独特的可能性。我们发现5.8 nm厚的W/CoFeB/Pt三层可以产生覆盖1- 30thz范围的超短脉冲。我们的新型光源在带宽、太赫兹场振幅、灵活性、可扩展性和成本方面优于ZnTe（110）晶体等激光振荡器驱动的发射器。
Terahertz electromagnetic radiation is extremely useful for numerous applications, including imaging and spectroscopy. It is thus highly desirable to have an efficient table-top emitter covering the 1-30 THz window that is driven by a low-cost, low-power femtosecond laser oscillator. So far, all solid-state emitters solely exploit physics related to the electron charge and deliver emission spectra with substantial gaps. Here, we take advantage of the electron spin to realize a conceptually new terahertz source that relies on three tailored fundamental spintronic and photonic phenomena in magnetic metal multilayers: ultrafast photoinduced spin currents, the inverse spin-Hall effect and a broadband Fabry-Perot resonance. Guided by an analytical model, this spintronic route offers unique possibilities for systematic optimization. We find that a 5.8-nm-thick W/CoFeB/Pt trilayer generates ultrashort pulses fully covering the 1-30 THz range. Our novel source outperforms laser-oscillator-driven emitters such as ZnTe(110) crystals in terms of bandwidth, terahertz field amplitude, flexibility, scalability and cost.