Silicon Photonic FMCW LiDAR Calibration Engine With Optimized On-Chip Delay Lines
Jing Wang, Jiawen Liao, Lin Zhu, Penghui Dong, Xiong Jiang, Hao Wang, Qifeng Liu
Abstract
This study presents the comprehensive design, optimization, and experimental validation of an advanced silicon photonic delay line tailored for nonlinearity calibration in frequency-modulated continuous-wave (FMCW) LiDAR systems. The novel delay line employs a hybrid architecture combining Archimedes' and Euler's spirals, which significantly minimizes connection loss and higher-order mode crosstalk, resulting in a low-loss, high-density optical path. Fabricated using a standard CMOS multiple project wafer (MPW) process, the delay line achieves 0.24 dB/cm loss and 7.56 ns optical delay within a compact 1 × 3 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> area, representing a substantial 41.5% improvement in delay density over our prior designs. Experimental outcomes validate the engine's capability for nonlinearity calibration, demonstrating a notable enhancement in signal-to-noise ratio and linewidth narrowing post-calibration. This work paves the way for the development of multifunctional, highly integrated FMCW LiDAR optical-electrical engines through the optimization of essential packaging and circuit functionalities.