OTDR modules are full function in small form factor with high performance, easy to be integrated into the system for optical fiber link quality monitoring. The form factor could be modular or pluggable(XFP/QSFP28/SFP+) to supporting different dynamic range. The OTDR Module has been developed for the detection of faults in optical fiber during the maintenance of optical fiber systems. It can be used to measure the total loss, interval loss, and cable length (distance) of an optical fiber system.