Performance of Ge/Si receivers at 1310 nm

We have studied three types of these detectors; normal incident illuminated p–i–n detectors (NI-PD), waveguide p–i–n detectors (WG-PD), and avalanche photodetectors (APDs) operating over a wavelength range of 850–1550 nm. NI-PDs have achieved −14.5 dBm sensitivity at 10 Gb/s and 850 nm, which is comparable to similarly commercially packaged GaAs devices. Unlike GaAs detectors, however, the Ge detectors scale well out to 1310 nm, because Ge has a much smaller bandgap. WG-PDs have achieved bandwidths of approximately 30 GHz at 1550 nm with internal quantum efficiencies of 90%, and similar, or better, performance is also expected at 1310 nm. Normal incident APDs operating at 1310 nm have achieved a primary responsivity of 0.54 A/W with a 3-dB bandwidth of 9 GHz at a gain of 17. A gain-bandwidth product of 153 GHz has been measured which generally exceeds that of a commercial InP-based APD.