The Development of High-Speed (Beyond 25 Gbit/Sec) and High Linearity Avalanche Photodiode for the Applications of High-Capacity and Long-Reach Ethernet( II )

Avalanche photodiodes (APDs) which operate at the 1.55 jam wavelength have recently attracted a lot of attention due to their superior performance in sensitivity to that of p-i-n photodiodes. Now APDs operated at 10 Gbit/sec is very popular and has strong demanding in the market of passive optical network (PON). However, compared with the p-i-n PDs, APDs usually have a much slower internal speed, because of the secondary-hole (or electron) drift-time and avalanche delay time inside its active layer. These bandwidth limiting factors become obstacles to further boost the speed of APD to meet the requirement of next generation (100) 400 Gbit/sec Ethernet. In (100) 400 Gbit/sec fiber communication system, receiver with high sensitivity and can be operated at the data rate as high as 25 or 50 Gbit/sec per channel are necessary. Furthermore, a high-linearity performance in such high-speed/-sensitivity APD is also required due to the appearance of burst-mode signal in the receiving end.In this work, we will demonstrate a novel p-side up mesa type In0.52Al0.48As based APD with partially depleted p-type absorber inside. By utilizing our proposed mesa structure, the high-E field would be strongly confined in the bottom and center parts of device without exposing to the air. This should greatly benefit its reliability performance. In addition, the partially depleted absorber in our structure can effectively shorten the hole drift-time without sacrificing the efficiency performance.In order to pursue such high-speed performance (>25 Gbit/sec) in APD, a thin (< 100 nm) In0.52Al0.48As based multiplication (M-) layer is usually required. However, this would result in a tremendous increase of dark current (and its induced short-noise) and may degrade the sensitivity performance of APD. In this project, we will also adopt a novel design of multiplication layer; “strained multiplication layer，，，which can minimize the increase of dark current with the decrease of M-layer thickness. We will also incorporate the DBR layers in the bottom of our active APD to further enhance its efficiency performance.Overall, by combing with the above-mentioned device technology with advanced package technology, which is supported by Source Photonic Company, we will demonstrate a high-linearity/-sensitivity-/ and reliable APD based photo-receiver module for next-generation (100) 400 Gbit/sec Ethernet communication system.