Flexible terahertz devices are becoming increasingly vital for applications in wearable photonics, intelligent communication, and flexible imaging. However, practical deployment has been hindered by the susceptibility of these devices to mechanical deformation, which can cause structural changes, information loss, or signal interruption. Addressing 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 Te/PET films that function as ultrafast all-optical terahertz modulators. The work is published in Light: Advanced Manufacturing.
The novel modulators utilize tellurium (Te) nanofilms grown on polyethylene terephthalate (PET) substrates. Te is chosen for its unique helical chain structure, good optical response, high carrier mobility, and ambient stability, making it an ideal material for terahertz modulation. When integrated with the flexible PET substrate, the Te nanofilms form mechanically robust and optically active films. The device exhibits a high modulation depth of 50% on a picosecond timescale, with broadband response and low insertion loss, even under low pump excitation. These attributes underscore the potential of Te/PET films for flexible terahertz functional devices.
A key aspect of the study was evaluating the mechanical stability of the device. The transient terahertz photoresponse remained nearly unchanged after repeated bending cycles and under a small bending radius, demonstrating excellent tolerance to mechanical deformation. This robustness is attributed to the mechanical resilience of Te nanofilms and the flexibility of the PET substrate, which together maintain reliable terahertz modulation even in complex deformation environments.
To explore the information-processing capabilities, the researchers integrated the measured terahertz modulation response into an artificial neural network (ANN) for image recognition tasks. The recognition accuracy remained stable under different bending conditions, indicating that the mechanical robustness of the Te/PET device translates into reliable information processing. This suggests that flexible terahertz modulators could serve as front-end functional units for intelligent sensing and neuromorphic optoelectronic systems.
The scientists summarize their work: "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 add, "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." The team forecasts that "the results provide a new device strategy for flexible terahertz modulators and offer guidance for the development of mechanically robust terahertz optoelectronic devices operating in complex deformation environments."
This research was supported by several grants, including the National Key R&D Program of China, the Postdoctoral Fellowship Program of CPSF, Beijing Natural Science Foundation, and others. The findings pave the way for the next generation of flexible terahertz technology, with implications for wearable devices, smart communication, and advanced imaging systems.
