Silicon-based traveling-wave photodetector array (Si-TWPDA) with parallel optical feeding

We demonstrate silicon-based traveling-wave photodetector arrays (Si-TWPDAs) with parallel optical feeding by integrating multiple Germanium photodetectors. Such Si-TWPDAs feature the merit of high optical saturation power with remaining the large operation bandwidth. The impedance-matched traveling-wave electrode design takes into account the individual Ge photodetector loading effect. Optical waveguide delay lines are designed in order to balance the electrical phase delay of the traveling-wave electrode. The maximum linear photocurrent at -4V biased voltage are respectively 16 mA, 38 mA, and 65 mA with integrating 1, 2, and 4 photodetectors, upon the saturation power of 40 mW, 100 mW, and 160 mW. This corresponds to a normalized photocurrent generation of >0.32 mA/mu m(3) and a normalized saturation power of 0.8 mW/mu m(3). The extracted fiber access responsivity is similar to 0.42 A/W and the intrinsic responsivity of similar to 0.82 A/W. The measured 3-dB bandwidth for 4-channel TWPDA is similar to 20 GHz. (C)2014 Optical Society of America