基于范德华铁电体NbOI$_2$的超快可调谐强太赫兹发射
Colossal terahertz emission with ultrafast tunability based on van der Waals ferroelectric NbOI$_2$
AI总结：
本文发现范德华铁电半导体NbOI$_2$具有比ZnTe高一个数量级的太赫兹发射效率，并揭示了其与铁电极化相关的机制，同时演示了双泵浦方案下的超快相干调控，为高性能太赫兹器件奠定基础。
摘要：
太赫兹（THz）技术对量子材料物理、生物医学成像、超快电子学以及下一代无线通信至关重要。然而，阻碍其广泛应用的关键在于缺乏兼具按需快速调制和易于片上集成能力的高效超快太赫兹源。本文报道了在范德华（vdW）铁电半导体NbOI$_2$中发现强太赫兹发射。利用太赫兹发射光谱，我们观察到其太赫兹产生效率比标准超快太赫兹产生非线性晶体ZnTe高一个数量级。通过研究太赫兹发射对激发波长、入射偏振和通量的依赖关系，我们进一步揭示了与其大铁电极化相关的潜在产生机制。此外，我们采用双泵浦方案，演示了太赫兹发射及其相关相干声子振荡的超快相干放大与湮灭。这些发现结合第一性原理计算，为新兴vdW铁电体中太赫兹光-物质相互作用提供了新认识，并为在其上开发用于量子材料传感和超快电子学的高性能太赫兹器件铺平了道路。
英文摘要：
Terahertz (THz) technology is critical for quantum material physics, biomedical imaging, ultrafast electronics, and next-generation wireless communications. However, standing in the way of widespread applications is the scarcity of efficient ultrafast THz sources with on-demand fast modulation and easy on-chip integration capability. Here we report the discovery of colossal THz emission from a van der Waals (vdW) ferroelectric semiconductor NbOI$_2$. Using THz emission spectroscopy, we observe a THz generation efficiency an order of magnitude higher than that of ZnTe, a standard nonlinear crystal for ultrafast THz generation. We further uncover the underlying generation mechanisms associated with its large ferroelectric polarization by studying the THz emission dependence on excitation wavelength, incident polarization and fluence. Moreover, we demonstrate the ultrafast coherent amplification and annihilation of the THz emission and associated coherent phonon oscillations by employing a double-pump scheme. These findings combined with first-principles calculations, inform new understanding of the THz light-matter interaction in emergent vdW ferroelectrics and pave the way to develop high-performance THz devices on them for quantum materials sensing and ultrafast electronics.
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