InP-based high-speed monolithic PIN photodetector integrated with an MQW semiconductor optical amplifier

Abstract

We demonstrate an InP based high speed p-i-n photodetector monolithic integrated with MQW semiconductor optical amplifier. A butt-joint scheme is adopted to connect the SOA and evanescent wave photodetector. The chip allows separate design for SOA and PD and needs only two MOCVD growth steps, which promises high yield and reduced manufacturing cost. The fabricated 5×20 μm2 PD shows a low dark current of 300 pA at -3V. The optical gain bandwidth of the SOA is 50nm, covering whole c-band. Gain ripple of SOA is 0.5dB, indicating that internal parasitic reflectivity is negligible. For integrated chip with 500μm SOA, the on-chip gain and total chip responsivity at 1545 nm can reach 12.8 dB and 7.8 A/W respectively. Insertion loss of the butt-joint interface is estimated to be 1.05 dB/interface. Small signal 3dB bandwidth at -5V of the integrated chip reaches 20GHz, showing no deterioration compared to discrete PD.