The Optical Time Domain Reflectometer (OTDR) is useful for testing the integrity of fiber optic cables. It can verify splice loss, measure length and find faults. OTDR testing analyzes fiber optic cable performance from end to end by testing components along the cable, including connection points, bends, and splices. What Is an OTDR? What Is an OTDR? An OTDR is. e an essential tool for: characterisation, certification, maintenance and monitoring optical networks. They characterise the len th, attenuation and return loss (ov se individual events along ink: connection points (splices, connectors), te ng by particles much smaller than the wavelength of the. On a transmission network, one cause of insertion loss on a fiber link is macro bending. As Fiber-to-the-Home (FTTH) networks lead to a significant increase of fiber installation in the last mile, the space constraints become increasingly. Abstract- In this paper, showed the measurement of bend loss in single mode fiber and multimode fiber in different bend radius at different wavelength by using OTDR and compares the value of bend loss of single mode fiber with standard paper and also performed reduce the bend loss at particular. Optical time domain reflectometry (OTDR) is at the heart of quality assurance in the fiber optic network.