Sensitivity of High-Speed Lightwave System Receivers Using InAlAs Avalanche Photodiodes

Calculations based on a rigorous analytical model are carried out to compare the sensitivity of optical receivers that use InP and In_0.52Al_0.48As avalanche photodiodes (APDs). The model includes the effects of intersymbol interference, tunneling current, avalanche noise and its correlation with the stochastic avalanche duration, dead space, and transimpedance amplifier noise. For a 10-Gb/s system with a bit-error rate of 10^-12, the optimum receiver sensitivity predicted for In_0.52Al_0.48As and InP APDs is -28.6 and -28.1 dBm, respectively, corresponding to a reduction of 11% in optical signal power for receivers using In_0.52Al_0.48As APDs. Thus, considering overall receiver sensitivity, the improvement offered by In_0.52Al_0.48As APDs over InP is modest.