ABSTRACT In this study, an 80 km. long fiber-optic data communication system is designed by using Raman amplifier. Chaotic communication technique is used contrary to regular data communication principles. The  components of the chaotic signal are the optical noise by AWGN (Additive White Gaussian Noise,AWGN) technique and ONA (Optical Noise Adder,ONA) in addition to the modulated signal which is obtained by using external optical modulator. Non-return to zero (NRZ) technique is selected in the design.  Key Words:Raman amplifier, Chaotic communication, Chaotic modulation, Chaos, Data communication