All-silicon and in-line integration of a variable optical attenuator and photodetector

We demonstrate in-line integration of a variable optical attenuator (VOA) and a photodetector (PD) based on a submicrometer silicon rib waveguide for 1550 nm. These devices are lateral p-i-n diodes. The VOA works in basis of free carrier absorption by carrier injection, while the PD utilizes defect-level-mediated photon absorption. We present characterizations of the PD and synchronous operation of those devices.