Integrated Waveguide Bridge Balanced Photodetector with High Common‐Mode Rejection Ratio for FMCW LiDAR

Abstract Recently, light detecting and ranging (LiDAR) technology has gained significant attention due to its wide‐ranging applications, particularly in 3D terrain mapping, atmospheric measurement, and autonomous driving. Most commercially available LiDAR systems employ mechanical beam steering, which presents limitations such as slower scanning speeds, lower reliability, and larger device size. In contrast, solid‐state LiDAR is emerging as a viable alternative, offering enhanced performance and integration potential. Among the various techniques, frequency‐modulated continuous wave (FMCW) LiDAR stands out, especially for its suitability in velocity measurements and its compatibility with silicon‐based integration. This work introduces a new bridge‐balanced photodetector (Bridge‐BPD) for enhanced performance in FMCW LiDAR systems. By integrating optical couplers and Germanium‐Silicon photodetectors (Ge/Si PDs), this BPD improves the common‐mode rejection ratio (CMRR) by up to 12.8 dB compared to traditional methods, achieving 45.8 dB at a wavelength of 1550 nm. With FMCW LiDAR systems, high detection sensitivity is demonstrated and a detection probability of 90% at −98 dBm. This novel BPD offers results comparable to commercial InP‐based detectors, paving the way for further optoelectronic integration in LiDAR applications.