Coherent LiDAR With an 8,192-Element Optical Phased Array and Driving Laser

Abstract

We present recent advancements of optical phased array LiDAR with record-performance system demonstrations. First, we give an overview of the technology and how it combines the benefits of coherent LiDAR with the integration capabilities of silicon photonics. Then, an 8192-element optical phased array is shown with individually-addressed elements driven by custom CMOS electronics. This compact chip-scale beam-steering engine is enabled by flip-chip attached ASICs on the photonic integrated circuit. The optical phase shifters and emitters in the array have a 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> m pitch to enable a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$100^{\circ }\times 17^\circ$</tex-math></inline-formula> field of view. This unprecedented number of active elements forms a near centimeter-scale aperture. Next, a high-performance laser uniquely suited for optical phased array LiDAR is demonstrated. Due to the silicon photonics cavity, it simultaneously supports a large tuning range (60 nm), low linewidth ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sim$</tex-math></inline-formula> 50 kHz), and fast linear chirp (1.3 GHz in 17.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> s). Finally, a solid-state coherent LiDAR system is realized with transmit/receive optical phased arrays coupled to an on-chip coherent receiver while being driven by the demonstrated laser. Ranging is shown on diffusive targets while simultaneously extracting velocity at each point in the point cloud. To the best of our knowledge, this single-unit compact system represents the state-of-the-art in optical phased array LiDAR technology.