Whether it is a large data center or millions of supercomputers, high-bandwidth and high-efficiency optical interconnections are required. Therefore, the silicon optical interconnection technology has attracted much attention due to its high integration and low cost advantages. The high-order modulation code pattern can further increase the data rate under the limited bandwidth of integrated circuits or optical devices, so it is more and more favored by academia and the industry. However, the signal-to-noise ratio of the optical link may be affected and reduced. At this time, a higher-power laser or a higher-sensitivity receiver is required to maintain the original bit error rate. Photodiodes can handle this task. Next, let's discuss the application of photodiodes in receiving.

　　 Compared with the use of high-power lasers, the use of a more sensitive receiver can reduce the total link power consumption, thereby improving energy efficiency. Especially for high-sensitivity detectors, the link budget requirement for the on-chip limited power laser is reduced, so an avalanche photodiode detector with internal gain is an ideal choice for improving the receiving sensitivity.

Because the avalanche diode detector generates additional noise while generating gain, in order to achieve higher gain and lower noise, researchers have been working to design a better silicon germanium thickness and doping distribution Of the device. In general, the design indicators of avalanche photodiode detectors need to weigh the breakdown voltage, quantum efficiency, multiplication gain, device bandwidth and additional noise. Breaking through this trade-off and optimizing the overall performance is a major challenge in the design of avalanche photodiode detectors.

　　 Avalanche photodiode detectors and distributed Bragg reflectors break the design trade-off between quantum efficiency and device bandwidth, and still have the advantages of high multiplication rate, low breakdown voltage and low additional noise without the need for additional noise.