Contents 1. Introduction
Light detection and ranging (LiDAR) is rapidly gaining more interests in both academia and industry for its versatile application. Although more mature LiDAR technologies based on mechanical scanners already exist, solid-state beam steering is considered a highly promising alternative because it could dramatically decrease the cost and size of LiDAR modules. Among different solid state approaches, a CMOS-process-based silicon-photonic optical phased array (OPA) on a chip is attracting more attention because it enjoys the benefit of advanced process control that enables a high level of integration. Previously, the silicon-photonic OPAs showed excellent steering performance and beam quality in small form factors [1], [2], but the detection ranges had been limited to a few meters due to heavy insertion losses of 10–20 dB, which resulted in weak output power [3], [4]. The range was extended over 100 m using coherent detection but at the expense of increasing the system complexity [5]. In another study, a device with an on-chip amplifier was reported [6], but it only discussed beam-steering performance without mentioning the final output power which is an important parameter that determines the ranging distance.
