The Fiber Optic Repeater is designed to solve problems of weak mobile signal in the place that is far away from the base station (BS) and has fiber optic cable network underground. The system consists of two parts: Donor unit and Remote unit. The Donor unit captures the BS signal via direct coupler closed to BS, then coverts it into optic signal and transmits the amplified signal to the Remote unit via fiber optic cable. The Remote unit will reconvert the optic signal into RF signal and provide signal to the areas where network coverage is inadequate.