Instead a fiber mating sleeve (adapter, or coupler) sits between two connectors. In this tutorial. There are many types of fiber optic connectors, including SC, LC, FC, ST, D4, MU, MT/MPO, etc. Fiber optic connector type are as various as the applications for which they were developed. Different connector types have different characteristics, different dvantages and disadvantages, and different performance cylinder. The fiber connector is called a fiber optic or optical fiber connector.