This experiment deals with the unique property possessed by an optical fiber communication system where light travelling in one direction is largely unaffected by light travelling in opposite direction along the same fiber. The ability of light to travel in both direction along an optical fiber without interfering allows us to use them for bidirectional communication. Here the loading and unloading of the signals at each end is more involved because both ends of the fiber must be connected to both a transmitter and a receiver.

         The following figure shows the basic block diagram of a bi-directional fiber optic communication system.