科学家实现具有范德华异质结构的太赫兹声子工程
近日，美国加州大学的Feng Wang及其研究团队取得一项新进展。经过不懈努力，他们实现具有范德华异质结构的太赫兹声子工程。相关研究成果已于2024年6月26日在国际权威学术期刊《自然》上发表。
该研究团队成功地在范德华异质结构中精准集成原子薄层，以高效生成、检测和操控太赫兹声子。他们运用少层石墨烯作为超宽带声子换能器，将飞秒近红外脉冲转化为光谱范围高达3THz的声子脉冲，同时利用单层WSe2作为传感器。这一过程中，高保真读数的实现得益于激子-声子耦合与强光-物质相互作用的共同作用。通过在单一异质结构中结合这些功能，并检测入射机械波的响应，研究人员成功进行了太赫兹声子光谱分析。
基于该平台，他们不仅展示了高品质因子（q）的太赫兹声子腔，还证明了嵌入六方氮化硼的WSe2单层能够有效阻隔太赫兹声子的传输。通过与纳米力学模型的比较，他们进一步揭示了异质界面处的力常数。这项研究结果不仅使太赫兹声子超材料能够用于超宽带声学滤波器和调制器，也为热工程开辟了新的途径。
据悉，千兆赫频率的声子工程是微波声滤波器、声光调制器和量子换能器的基础。太赫兹声子工程可能导致更高带宽和速度的声学滤波器和调制器，以及在更高温度下工作的量子电路。尽管太赫兹声子具有潜力，但由于在亚纳米精度下实现所需的材料控制和在太赫兹频率下实现有效的声子耦合的挑战，工程太赫兹声子的方法受到限制。
附：英文原文
Title: Terahertz phonon engineering with van der Waals heterostructures
Author: Yoon, Yoseob, Lu, Zheyu, Uzundal, Can, Qi, Ruishi, Zhao, Wenyu, Chen, Sudi, Feng, Qixin, Kim, Woochang, Naik, Mit H., Watanabe, Kenji, Taniguchi, Takashi, Louie, Steven G., Crommie, Michael F., Wang, Feng
Issue&Volume: 2024-06-26
Abstract: Phonon engineering at gigahertz frequencies forms the foundation of microwave acoustic filters, acousto-optic modulators and quantum transducers. Terahertz phonon engineering could lead to acoustic filters and modulators at higher bandwidth and speed, as well as quantum circuits operating at higher temperatures. Despite their potential, methods for engineering terahertz phonons have been limited due to the challenges of achieving the required material control at subnanometre precision and efficient phonon coupling at terahertz frequencies. Here we demonstrate the efficient generation, detection and manipulation of terahertz phonons through precise integration of atomically thin layers in van der Waals heterostructures. We used few-layer graphene as an ultrabroadband phonon transducer that converts femtosecond near-infrared pulses to acoustic-phonon pulses with spectral content up to 3THz. A monolayer WSe2 is used as a sensor. The high-fidelity readout was enabled by the exciton–phonon coupling and strong light–matter interactions. By combining these capabilities in a single heterostructure and detecting responses to incident mechanical waves, we performed terahertz phononic spectroscopy. Using this platform, we demonstrate high-Q terahertz phononic cavities and show that a WSe2 monolayer embedded in hexagonal boron nitride can efficiently block the transmission of terahertz phonons. By comparing our measurements to a nanomechanical model, we obtained the force constants at the heterointerfaces. Our results could enable terahertz phononic metamaterials for ultrabroadband acoustic filters and modulators and could open new routes for thermal engineering.
DOI: 10.1038/s41586-024-07604-9
Source: https://www.nature.com/articles/s41586-024-07604-9
来源：科学网 小柯机器人
