When the laser diode is working at steady-state condition, there exists so many harmonics in optical power such as first, second, third and so on. The difference frequencies obtained from these harmonics are used in subcarrier intermodulation (IMD) and asymmetric communication systems. In the analysis, Volterra power series expansion method is used. The series is expanded up to third degree and small signal transfer function is obtained from Volterra operators. The expansion is based on H1,H2 and H3 Volterra kernels and small signal transfer function that is organized from H1 kernel is used in the calculations. For the non-linear optoelectronic feedback laser diode system, the normalized frequency and harmonic values are computed with respect to feedback time delay ( 0 t ) for the effective values of the feedback constant (K). Amplitudes of harmonics are controlled by decreasing, increasing or suppressing dependent upon the critical time delays.