High-speed, high-responsivity 1.55 mu m photodetector on InP

40 Gbit/s photodetectors require high bandwidth at high power levels, as supplied by waveguide-integrated p-i-n diodes on InP. Waveguide-integrated photodetectors on InP exhibit a high cutoff frequency above 60 GHz. By monolithic integration of a spot size transformer, a responsivity of 0.7 A/W is achieved and the fiber alignment tolerances are increased by one order of magnitude. Linear power behaviour up to +12 dBm at 50 GHz and maximum output voltage swings of 1 V are demonstrated.