High Speed and Broadband Fiber-Integrated Ws2/Bi2o2se Avalanche Photodetector

Photodetectors based on two-dimensional(2D) materials have attracted tremendous attention in recent years because of their potential for development in compact and integrated devices. Owing to the high carrier mobility and air stability, the newly discovered 2D bismuth oxyselenide (Bi 2 O 2 Se) exhibits outstanding optoelectronic properties. However, the high dark current inevitably restricts the performance of the Bi 2 O 2 Se-based photodetectors. Here, we propose and demonstrate a fiber-integrated photodetector with a low dark current of 10 -10 A by assembling a WS 2 /Bi 2 O 2 Se Van der Waals heterostructure onto the end-face of a standard optical fiber. Benefiting from the narrow bandgap of the 2D materials, the fiber-integrated photodetector exhibits a broadband detection range from 650 to 1620 nm along with a responsivity of 1.13 AW -1 . The fast rise time is measured as ~410 μs, while the fall time is ~600 μs. Taking advantage of the built-in potential in the WS 2 /Bi 2 O 2 Se heterostructure, the photodetector can work on self-powered mode. Applied a certain high reverse voltage, the WS 2 /Bi 2 O 2 Se fiber-integrated photodetector can operate at avalanche breakdown region with an external quantum efficiency of 141% and an avalanche gain of 44 under the input power of 56.7 µW. Finally, the fiber-integrated photodetector is applied to measure the wrist bending owing to its high photoresponsivity. These findings indicate that our proposed device has intriguing capabilities in terms of photodetection and on-line power monitoring, which enable our proposed device to have superb application potential in a fiber-integrated multi-function system.