Flexible terahertz devices are crucial for the advancement of wearable photonics and intelligent communication systems, yet their practical deployment is often hindered by mechanical deformation that can lead to signal loss and information degradation. In a significant step toward overcoming this challenge, a research team led by Professor Qingli Zhou from Capital Normal University and Professor Chen Ge from the Institute of Physics, Chinese Academy of Sciences, has developed flexible tellurium (Te) nanofilms on polyethylene terephthalate (PET) substrates as ultrafast all-optical terahertz modulators. These devices exhibit high modulation efficiency, picosecond response, low insertion loss, and robust bending tolerance, as reported in the journal Light: Advanced Manufacturing.
The importance of this development lies in addressing a critical bottleneck in flexible terahertz technology. Terahertz modulators are essential components for controlling terahertz signals in various applications, including flexible imaging, sensing, and next-generation communication systems. However, traditional rigid modulators cannot withstand the bending and flexing required for wearable and flexible devices. The Te/PET films offer a promising solution by combining the unique properties of tellurium—such as its helical chain structure, excellent optical response, high carrier mobility, and ambient stability—with the flexibility of PET substrates. This combination results in a mechanically robust and optically active film capable of reliable terahertz modulation even under mechanical stress.
In their experiments, the researchers demonstrated that the Te/PET modulator achieves a high modulation depth of 50% on a picosecond timescale, with broadband operation and low insertion loss. Notably, the device exhibits an ultrasensitive response under low pump excitation, indicating its efficiency. The mechanical stability was thoroughly evaluated by subjecting the device to repeated bending cycles and small bending radii. The transient terahertz photoresponse remained nearly unchanged, highlighting the excellent mechanical tolerance of the Te nanofilms and the flexibility of the PET substrate. This stability is crucial for ensuring consistent performance in real-world flexible applications.
Furthermore, the team explored the information-processing capabilities of the device by integrating its measured terahertz modulation response into an artificial neural network (ANN) for image recognition tasks. The recognition accuracy remained stable under different bending conditions, demonstrating that the mechanical robustness of the Te/PET device can be effectively translated into reliable information processing. This suggests that flexible terahertz modulators could serve as front-end functional units for intelligent sensing and neuromorphic optoelectronic systems, which are expected to play a pivotal role in future smart devices.
The scientists summarized their work by stating, "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 added, "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 can operate in complex deformation environments. The findings are published with the DOI 10.37188/lam.2026.086 and are expected to accelerate the adoption of flexible terahertz technology in various fields.
