LAUSR

Abstract. We propose a simple scheme to perform real-time and rapid measurements of the loop gain and bandwidth of a phase-locked loop (PLL) for mode-locked lasers. By implementing the proposed scheme, the loop gain and bandwidth of a laser-based PLL can be directly and accurately characterized in real time without breaking the original loop. The experimental loop-gain and bandwidth measurement results were found to precisely agree with the simulation results, thereby confirming that the proposed scheme is accurate and reliable. This scheme, with its simple configuration, can be easily expanded to other laser-locking systems that require precise measurements of the loop gain and bandwidth.