Multifunctional Waveguide Tunnelling via Leaky Modes

• Published in: Laser & photonics reviews Vol. 18; no. 10
• Main Authors: Hu, Chuanjie, Li, Jue, Kong, Xianghong, Xue, Shuwen, Zhang, Zhibin, Tao, Sicen, Xiao, Wen, Zhu, Shan, Qiu, Cheng‐Wei, Chen, Huan‐yang
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.10.2024
• Subjects: beam steering; Bridge maintenance; Evanescent waves; Leaky modes; multifunctional mode tunnelling; Optical filters; Optical switching; Tunnel construction; Wave diffraction; Wave dispersion; Waveguides
• ISSN: 1863-8880; 1863-8899
• DOI: 10.1002/lpor.202301398

Much effort in the past few years has been made in tunnelling, however, no work has been reported so far on how to maintain the maximum tunnelling of complex optical fields in waveguides, due to the limitations of existing physical mechanisms. Here, a new paradigm is presented for realizing anomalous wave tunnelling through a general effective double‐barrier model constructed by dispersion engineering, while preserving mode information. The observed tunnelling mechanism is corroborated well by experimental results in the microwave realm. Specifically, evanescent waves bridge the gap between external space and potential well, allowing us to modulate the leaky modes within the potential well and thus achieve multiple resonant tunnelling. Due to the constant phase difference between adjacent maximum tunnelling, such mechanism broadens the potential of binary integrated devices. For example, assembling the tunnelling unit into arrays straightforwardly alleviates the trade‐off dilemma between diffraction law and cut‐off frequency. In addition, this approach provides an ideal toolbox for achieving multifunctional tunnelling across waveguide modes of various orders or polarizations, which can boost various applications in optical filters, tunneling lasers, optical switching, and sensing. This study demonstrates anomalous waveguide tunnelling through dispersion engineering, well corroborated by experimental results. Assembling the tunnelling units into arrays alleviates the trade‐off dilemma between diffraction law and cut‐off frequency. This mechanism provides a toolbox for achieving multifunctional tunnelling across waveguide modes of various orders or polarizations, which can boost various applications in optical filter, optical switching, and sensing.