40 Gbit/s waveguide avalanche photodiode with p-type absorption layer and thin InAlAs multiplication layer

Waveguide avalanche photodiodes exhibiting both wide bandwidth and high gain bandwidth product have been developed. An absorption layer includes a p-type quasi-field-formed layer and a multiplication layer consists of InAlAs with a low ionisation rate ratio. Optimisation of the design yielded superior performance such as a wide bandwidth of 36.5 GHz, a gain band width of 170 GHz and a high quantum efficiency of 0.75 A/W.