Significance LiDAR detects targets by actively emitting and receiving lasers, obtaining information such as distance, speed, and orientation from the laser reflection echoes.It serves as a fundamental source for multi-dimensional environmental perception. In the context of detection systems, Time of Flight (TOF) LiDAR uses pulsed light signals to measure distances by precisely calculating the flight time of reflected light pulses. However, it has poor anti-interference, low detection sensitivity, and is susceptible to rain and fog, snow and other severe weather effects and other disadvantages; Frequency Modulated Continuous Wave (FMCW) combines continuous frequency modulation ranging in modern radar technology with laser detection technology. It uses linear frequency modulation signals to modulate the laser, and obtains target information by measuring the frequency of the beat frequency signal obtained by coupling the reflected signal and the local oscillator signal, because the coherent detection method can achieve a higher signal-to-noise ratio with lower laser emission power, making it a promising technology for future applications. In recent years, with the rapid development of silicon-based optoelectronic integration technology, on-chip integrated FMCW LiDAR, capable of integrated ranging, speed measurement, and high-precision long-distance detection, has become a research hotspot and has been used in fields such as intelligent driving, aerospace, target monitor, and public security.
Progress In terms of scanning method, mechanical LiDAR uses mechanical rotation to achieve laser scanning, and uses a motor to drive the rotation of a single-point or multi-point ranging module. However, it is large in size, complex in assembly, and has a short lifespan, making it difficult to meet reliability and low-cost requirements. Dual-axis Micro-Electro-Mechanical Systems (MEMS) and transmissive poly-wedge prisms use single-point ranging combined with complex optical scanning systems. But face challenges such as limited detection range, poor environmental adaptability, and the inability to simultaneously improve angular resolution and scanning frame rate. The area array flash (Flash) is a non-scanning type. Area array flash LiDAR, a non-scanning type, outputs image information by receiving light speckles on the target. Despite its low cost and strong stability, its low emission energy density makes long-distance detection difficult, limiting its application scenarios. Thanks to the advancement of silicon-based optoelectronic integration technology, Optical Phased Array (OPA) has received widespread attention and rapid development. The solid-state beam forming and steering capabilities it provides play an important role in free-space applications and can simultaneously meet the requirements of detection field of view and resolution rate and scanning frequency requirements, it is the preferred solution to balance various core indicators, achieve low cost, high reliability and excellent performance at the same time, which is the mainstream development direction of all-solid-state and miniaturized FMCW LiDAR in the future. This article focuses on the on-chip integrated FMCW LiDAR using OPA, explaining the system's working principles.It summarizes the development status of on-chip integrated FMCW LiDAR based on various research progress both domestically and internationally. Key technologies such as frequency modulation, transmission, scanning and reception are also sorted out, and the applications and typical systems in related fields are reviewed. Finally, the analysis looks forward to the future development trends and potential challenges of on-chip integrated FMCW LiDAR.
Conclusions and Prospects The silicon-based optoelectronic integration technology has given birth to high-performance and low-loss on-chip optical devices, which have promoted the development of FMCW LiDAR in the direction of high integration and miniaturization. The on-chip integrated FMCW LiDAR based on OPA scanning has many advantages such as fast scanning rate and strong stability. As technology research and product development continue to deepen, on-chip integrated FMCW LiDAR will show greater potential and value in academic research and commercial applications.
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