In this study, a theoretical systematic approach is introduced as a solution of the bandwidth problem of multi-tone network systems. This systematic approach proposes the use of unused harmonic components of non-linear harmonic distortion produced by the semiconductor laser diode, which is used as a source in the infrastructure of the fiber optic communication system. In order to separate these unused harmonic distortion frequency components from the others, it is possible to add a protocol to each harmonic distortion difference frequency signal, or by intermodulation distortion (IMD) phase modulation, or to use both protocol and IMD phase modulation together. Thus, all harmonic distortion frequency components can be separated theoretically. Thus, it is recommended to use IMD difference frequency components in multi-tone-input subcarrier fiber optic or similar communication systems in the same transmission medium. We think that if this technique is used, it will make a great contribution to increasing the bandwidth of fiber optic communication and network systems.