Waveguide Integrated Balanced Photodetectors for Coherent Receivers

This paper presents a brief review of waveguide integrated balanced photodetectors for coherent receivers and describes some of their recent progresses. Waveguide integrated balanced photodetectors and balanced photodiodes (PD) monolithically integrated to InP-based coherent receiver photonic integrated circuits (PIC) are discussed. On one hand, the devices focus on high-end market for long-haul transmission, and on the other hand on short reach transmission for data centers. In this paper, also a balanced photodetector with the highest ever reported 3-dB bandwidth of 115 GHz is demonstrated. Moreover, a low-power concept for a homodyne receiver PIC with balanced avalanche PD is emphasized to introduce phase modulation formats to data center transmissions.