Phonon engineering at gigahertz frequencies forms the foundation of microwave acoustic filters¹, acousto-optic modulators² and quantum transducers^3,4. 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 3 THz. 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.

千兆赫频率的声子工程构成了微波声滤波器 ¹ 、声光调制器 ² 和量子换能器 ^3,4 的基础。太赫兹声子工程可以带来更高带宽和速度的声滤波器和调制器，以及在更高温度下运行的量子电路。尽管具有潜力，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高效声子耦合的挑战，太赫兹声子的工程方法受到限制。在这里，我们展示了通过在范德华异质结构中精确集成原子薄层来有效生成、检测和操纵太赫兹声子。我们使用几层石墨烯作为超宽带声子换能器，将飞秒近红外脉冲转换为频谱含量高达 3 THz 的声学声子脉冲。单层WSe ₂ 用作传感器。高保真读数是通过激子-声子耦合和强光-物质相互作用实现的。通过将这些功能结合在单个异质结构中并检测对入射机械波的响应，我们进行了太赫兹声子光谱。利用该平台，我们演示了高Q太赫兹声子腔，并表明嵌入六方氮化硼中的WSe ₂ 单层可以有效阻挡太赫兹声子的传输。通过将我们的测量结果与纳米力学模型进行比较，我们获得了异质界面处的力常数。我们的研究结果可以使太赫兹声子超材料用于超宽带声滤波器和调制器，并可以为热工程开辟新途径。