Optical Phased-Array Fmcw Lidar With On-Chip Calibration

Light detection and ranging (lidar) sensors provide high resolution and high accuracy for diverse applications such as autonomous vehicles and three-dimensional imagers. Over the past few years, there has been significant development towards compact, low-power, and low-cost realization of lidars. Recently, silicon-based large-scale optical phased arrays operating at around 1550nm [1 –4] along with their application in lidar [5] [6] have been demonstrated. A major challenge associated with large-scale optical phased arrays is the inevitable mismatches across the array that necessitate array calibration. At present, all large-scale arrays are calibrated by using an external optical detector for measuring focused far-field beam spot intensity [3] or infrared image sensors for measuring the far-field radiation patterns in the lab [1] [2] [6]. This solution, which requires an external detector at a far-field distance, naturally does not lend itself to large-scale field deployment of optical phased arrays for commercial applications with a compact form factor.