Abstract: A fiber optic based security system is disposed on or in a structure such as a wall, roof, floor, ceiling, container, and/or ground. The security system contains an optical cable having first and second ends and an interface unit connected to both ends of the optical cable. The interface unit generates a specific light signal injected into the first end. The interface unit receives the specific light signal from the second end after the specific light signal propagates through the optical cable. The interface unit then determines if the specific light signal received falls within a given threshold and outputs an alarming signal indicating if the specific light signal received falls outside of the given threshold. An alarm system receives the alarming signal from the interface unit. The alarm system is activated if the interface unit indicates that the specific light signal falls outside of the given threshold.