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.