We are pleased to provide readers with the newest and important technologies presented in Asia Communications and Photonics Conference (ACP) and International Conference on Information Photonics and Optical Communications (IPOC) 2020 (ACP/IPOC 2020), through this Special Issue published by the IEEE Photonics Technology Letters (PTL) journal. Technologies of photonics and optical communications (POCs) have developed rapidly in the last decades and have evolved to become a key-enabling component for the applications of high-speed telecommunications, advanced microwave signal generation and processing, astronomy observations, and even for quantum information processing and computing. The field of POC continues attracting a great deal of attention and keeps progressing in several important directions. Based on the nowadays matured exploration methods, current research is mainly directed towards implementations in integrated formats, such as high-speed optical transmission, big-capacity optical switching, automated optical-network/system evolution, and so on. In addition, intensive research is being conducted toward the utilization of POC across the abovementioned practical application areas and others.