Ultrahigh‐Power Germanium Photodetector Enabling Amplifier‐Free Wireless Communication

Abstract Photodetector (PD), an indispensable component in radio‐over‐fiber (RoF) systems, functions as an interface between the optical fiber backbone and the wireless radio branches. The power‐handling capability is paramount to determine both coverage and linearity of the RoF link, and it is predominantly constrained by the space‐charge effect that limits output photocurrent. Consequently, electronic power amplifiers are required to ensure reliable wireless coverage for end‐users, albeit at the expense of degraded signal linearity, increased energy consumption, and bulky system. On the other hand, the increasing demand in co‐integration with silicon microelectronics indicates that CMOS‐compatible germanium‐silicon (Ge─Si) PDs hold significant promise. Herein, an ultrahigh‐power Ge─Si PD is designed and implemented with an unprecedented high saturation photocurrent of 471.4 mA and a responsivity of 1.12 A W −1 . The remarkable high‐power performance is achieved through enhancing optical power absorption and promoting photo‐generated carrier transit comprehensively. For a proof‐of‐concept demonstration, amplifier‐free wireless communication is achieved and driven by the proposed PD, enabling a range‐capacity product of 20 m·Gb s −1 , a third‐order output intermodulation power of 32.3 dBm at 5 GHz, along with a real‐time video stream transmission. This work exhibits a promising solution for on‐chip ultrahigh‐power photodetection, and represents a significant advancement toward high‐quality fiber‐wireless access network.