Enhanced three-channel dual-polarization silicon photonic balanced receiver for long-range FMCW laser ranging systems

Abstract

We present an improved three-channel dual-polarization silicon photonic balanced receiver specifically designed for frequency-modulated continuous-wave (FMCW) ranging systems. By leveraging silicon photonics technology, we have integrated previously discrete functional devices onto a single chip, significantly reducing system volume and enhancing integration. To address the limitations of existing multi-channel balanced receivers, we performed a systematic analysis and optimization of the receiver’s components. Our optimizations included enhancing photodetector responsivity, minimizing dark current, refining layout and wire bonding, optimizing packaging coupling processes, and improving the bandwidth and noise characteristics of the receiving link. As a result, we developed a germanium-silicon photodetector with a high responsivity of ∼ 1.09 A/W, minimal dark current of ∼ 4 nA, and bandwidth of 28 GHz. Furthermore, we realized a 3-channel dual-polarization balanced receiver chip using 130 nm CMOS technology, achieving low loss and crosstalk through layout optimization and effective packaging. The receiver was validated through an FMCW ranging system setup, demonstrating a ranging capacity exceeding 180 m across all three channels, outperforming previous works. Our receiver satisfies the potential demands of long-range and high-resolution FMCW ranging, particularly relevant for automotive LiDAR applications.