Avalanche photodiode with ultrahigh gain-bandwidth product of 1,033 GHz

Avalanche photodiodes (APDs) have enabled highly sensitive photodetection in optical communication, sensing and quantum applications. Great efforts have been focused on improving their gain-bandwidth product (GBP). However, further advance has encountered enormous barriers due to incomplete consideration of the avalanche process. Here we implement a germanium/silicon APD with the GBP breaking through 1 THz. The performance is achieved by introducing two cooperative strategies: precisely shaping the electric field distribution and elaborately engineering the resonant effect in the avalanche process. Experimentally, the presented APD has a primary responsivity of 0.87 A W-1 at unity gain, a large bandwidth of 53 GHz in the gain range of 9-19.5 and an ultrahigh GBP of 1,033 GHz under -8.6 V and at 1,550 nm. For demonstration, data reception of 112 Gb s-1 on-off keying and 200 Gb s-1 four-level pulse amplitude modulation signals per wavelength are achieved with clear eye diagrams and high sensitivity, as well as 800 G reception via four channels. This work provides a potential successor for high-speed optoelectronic devices in next-generation optical interconnects. Researchers demonstrate a germanium/silicon avalanche photodiode gain-bandwidth product over 1 THz operating at 1,550 nm wavelength. The findings have implications for future high-speed optoelectronic devices in next-generation optical interconnects.