Nowadays all parts of ICT network architectures need bandwidth, especially the need inside data center and DCI is growing explosively. AOC in different form factors such as SFP+, QSFP+ and CXP is the ideal choice for DCI. Its plug-and-play is suitable for applications of connection between racks, DCI, storage and HPC & switch. Currently the bandwidth of single fiber is over 100 Gb/s, and 400G DCI for next-generation data center in single mode fiber to be widely employed along with the rapid growth of cloud computing and Internet of Things.