Published in Light: Science & Applications, researchers from the Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, along with collaborators from Peking University and Xi'an Jiaotong University, introduce a novel approach to detecting the orbital angular momentum (OAM) of light using multilayer graphene (MLG), opening new possibilities for infrared imaging and optical communication. Detecting the orbital angular momentum (OAM) of light has long been a challenge, with existing materials suffering from instability and fabrication difficulties. Traditionally, type-II Weyl semimetals such as and have been used for OAM detection. However, these materials degrade under ambient conditions and are challenging to integrate into large-scale semiconductor devices.
This study demonstrated that MLG is a promising alternative, offering stability and compatibility with current semiconductor technologies.
The study presents an MLG-based photodetector with a specially designed U-shaped electrode geometry, enabling direct detection of the topological charge of OAM through the orbital photogalvanic effect (OPGE). Unlike conventional materials, MLG exhibits a significantly enhanced OPGE response due to its unique electronic properties. The reduced dimensionality of MLG leads to lower scattering rates, enhancing its detection capability and making it up to ten times more sensitive than in mid-infrared OAM detection.
Through rigorous experimentation, researchers validated the superior performance of MLG in detecting OAM in the mid-infrared range. The device's efficiency stems from its ability to convert helical light waves into electrical signals more effectively than previous materials. Additionally, MLG is both CMOS-compatible and epitaxially growable at wafer scale, making it an ideal candidate for industrial applications. The use of a radial photocurrent collection technique further improves the signal-to-noise ratio, ensuring precise and reliable detection.
The implications of this study extend beyond fundamental research, with potential applications in optical communication, quantum computing, and advanced infrared imaging. By enabling real-time, large-scale detection of OAM, MLG-based devices could revolutionize high-speed data transmission and anti-jamming technologies. Furthermore, its stability in ambient conditions ensures long-term reliability for practical deployment in aerospace, defense, and medical imaging.
This OAM detection marks a step forward in photonics research. Future work will focus on optimizing the detection speed and further integrating MLG detectors into existing optical systems. By leveraging its unique electronic properties, MLG has the potential to set new standards for high-performance mid-infrared photodetection.
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