150-GHz wide-bandwidth balanced photodetector for high-baud-rate PSK signal detection

We present a newly developed integrated high-speed balanced photodetector (BPD) with a 3 dB bandwidth of 150 GHz and a common-mode rejection ratio (CMRR) of -30 dB, along with its demonstration for high-speed DPSK signal detection targeting next-generation high-baud-rate digital coherent receiver applications. The BPD design employs a uni-traveling carrier (UTC) PD with a well-optimized epitaxial layer structure and a narrow-pitch layout for the two PDs. Using high-speed DPSK signals, we successfully demonstrated fundamental push-pull operation up to 100 Gbaud. The device design, fabrication, and measured characteristics of the BPD are discussed in conjunction with the signal detection demonstration.