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.