The Development of Optical Engine for Fmcw Lidar Based on Photonic Integrated Circuit Technology( II )

In the recent years, the development of Lidar technologies is booming due to its fancy applications in self-driving cars and unmanned vehicles. Now, lots of major car manufactures, big IT companies, and numerous star-up companies are dedicated to this topic. Up to now, most of the commercial available Lidar system is based on optical pulse at 905 nm wavelength, mechanical steering mirror, single-photon avalanche photodiode, and time-of-flight (ToF) technology. However, this kind of technology suffers the eye-safe issue when lots of cars are running Lidar system simultaneously. In addition, the size of this kind of Lidar module is usually bulky. In order to overcome the above-mentioned problems, we will demonstrate a frequency-modulated continuous-wave (FMCW) Lidar system and its novel core chip (optical engine) inside. In this FMCW lidar, we will push the operating wavelengths to around 1.55 m. Such optical window at telecommunication wavelengths can minimize the absorption in the retinal of people and we can realize our Lidar system based on the InP based photonic integrated circuit (PIC) technology, which is well-developed for the fiber communication industry. In addition, the PIC scheme can help us downscale the size of Lidar system. However, the major problems in the nowadays PIC is its huge Input/Output coupling loss (~10 dB) with outside environment. This is not acceptable for the self-driving car Lidar, which needs a capability in long range detection (>100 meter). In this project, we will have a hybrid integration for PIC, which is composed by DFB laser and phase-shifter array, with liquid crystal active lens. Based on such scheme, we can discard most of the lossy components in our PIC and realize 2-D scanning and 3-D imaging. Besides, we will demonstrate a novel avalanche photodiode (APD) array, which can provide high responsivity and high saturation current in the receiver end. By use of such gadget, an improved signal-to-noise (S/N) ratio and longer ranging distance can be expected.