InGaAs/InAlAs Avalanche Photodiode With Low Dark Current for High-Speed Operation

Waveguide InGaAs/InAlAs avalanche photodiodes (APDs) with high bandwidths (>40 GHz) and low dark current (<;50 nA at 90% of breakdown voltage) were demonstrated. The excess noise is low, corresponding to k ~ 0.2 line in the local excess noise model. Using these values bit error rate (BER) was calculated to assess the potential of our APDs. Calculated sensitivities of -21.5 dBm at 25 Gb/s and -14.2 dBm at 40 Gb/s are predicted for a BER of 10-10. Analysis showed that with lower amplifier noise, the low dark current and low excess noise from our APDs are necessary to optimize the sensitivity.