Optical Phase-Locked Loops

Phase-locked loop (PLL) plays an important role in wireless communication navigation, radar, and other fields. It affects the data processing rate of the whole system and the extraction of clock phase information. The optical phase-locked loop (OPLL) has the advantages of high-speed real-time reception, low power consumption, and strong ability to resist background light interference and Doppler frequency shift, and is the key circuit module of coherent optical communication system. Its performance directly affects the performance of optical communication system. The research of optical phase-locked loop is mainly aimed at optimizing and improving its parameters. This chapter reviews the research progress of the technology from electric phase-locked loop to optical phase-locked loop. Based on an introduction to the principle and key components, the classification and parameters of the electric phase-locked loop and optical phase-locked loop are introduced in detail, and the performance of various optical phase-locked loops is compared. This chapter summarizes the optical phase-locked loop technology in wireless coherent optical communication systems, and finally prospects its future development direction, which can provide reference for the research and development of phase-locked loop technology in different fields.