A heterodyne optical phase-locked loop for multiple applications

A novel heterodyne optical phase-locked loop (OPLL) has been achieved and testing results are demonstrated with a 0.03 rad
²
phase error variance. Based on the superior performance of this OPLL, a system prototype is shown for multiple applications, including free-space LIDAR systems, widely-and-fast-tunable ultra-narrow-linewidth lasers, and ultra-accurate optical spectrum analyzers.