High responsivity and wide bandwidth operation of InP-based pin-photodiode array monolithically integrated with 90? hybrid using butt-joint regrowth

The InP-based pin-photodiode array monolithically integrated with a 90° hybrid consisting of multimode interference structures was fabricated using the butt-joint regrowth for compact 100 Gbps coherent receivers. The low dark current of less than 0.2 nA was obtained with InP passivation effect through the selective regrowth process in four-channel photodiodes. A responsivity including total loss of 8.3 dB in the waveguide was as high as 0.14 A/W. The wide 3 dB bandwidth of 24 GHz at a low reverse bias voltage of 1.6 V was also achieved under high optical input power conditions (photocurrent: 4 mA).