Monolithic Integrated Silicon Polarization-Independent Tunable Filter Circuit With Germanium p-i-n Photodetector

We report the design, fabrication, and characterization of a monolithic integrated silicon polarization-independent optical tunable filter circuit with germanium p-i-n photodetector (PD). We demonstrate polarization transparent filter characteristics with an extinction ratio of ~22 dB, and a 3-dB bandwidth of 0.33 nm. The tuning range of the filter is ~11.5 nm. The measured fiber-to-PD responsivity of the photonic integrated circuit is ~0.10 A/W at a reverse bias of 5 V.