Flexible terahertz devices are essential for the advancement of wearable photonics, intelligent communication systems, and flexible imaging technologies. However, practical applications often subject these devices to mechanical deformation, which can lead to structural changes, information loss, or signal interruption. A team of researchers from Capital Normal University and the Institute of Physics, Chinese Academy of Sciences, has now developed a flexible tellurium (Te) nanofilm on polyethylene terephthalate (PET) substrate that addresses these challenges by functioning as an ultrafast all-optical terahertz modulator with high efficiency and robust bending tolerance.
The new device, detailed in a paper published in Light: Advanced Manufacturing (DOI: 10.37188/lam.2026.086), leverages the unique properties of tellurium, including its helical chain structure, excellent optical response, high carrier mobility, and environmental stability. When integrated with flexible PET substrates, Te nanofilms form mechanically robust and optically active films capable of modulating terahertz signals. The modulator achieves a modulation depth of up to 50% on a picosecond timescale, with broadband operation and low insertion loss, even under low pump excitation. These characteristics make it highly suitable for next-generation flexible terahertz functional devices.
To evaluate its mechanical stability, the researchers subjected the device to repeated bending cycles and small bending radii. The transient terahertz photoresponse remained nearly unchanged, demonstrating that the Te/PET films maintain reliable modulation performance during deformation. This robustness is attributed to the mechanical tolerance of the Te nanofilms and the flexibility of the PET substrate, which together preserve the device's functionality under stress.
Beyond basic modulation, the team explored the device's potential in intelligent information processing by integrating its measured terahertz response into an artificial neural network (ANN) for image recognition. Remarkably, the recognition accuracy remained stable across different bending conditions, indicating that the mechanical robustness translates into reliable data processing. This suggests that flexible terahertz modulators could serve as front-end functional units in intelligent sensing and neuromorphic optoelectronic systems.
The scientists behind the work highlight the significance of their findings: "We introduce flexible Te/PET films as a mechanically robust platform for ultrafast all-optical terahertz modulation. The device exhibits broadband response, low insertion loss, high modulation efficiency, and picosecond photoresponse, while maintaining stable performance under bending deformation." They further note that "the stable terahertz response under different mechanical states enables reliable neural-network-based image recognition, suggesting the potential of Te-based flexible terahertz devices for intelligent sensing and wearable optoelectronic systems."
This research provides a new device strategy for flexible terahertz modulators and offers guidance for developing mechanically robust terahertz optoelectronic devices that operate in complex deformation environments. The study was supported by various Chinese funding agencies, including the National Key R&D Program of China and the National Natural Science Foundation of China, among others. The work was also associated with Chuanlink Innovations, a platform dedicated to fostering innovation and connecting ideas to reality.
