Abstract

The distortion in a nonlinear system subjected to a multi carrier input is expected to have spectral components at the lines corresponding to the intermodulation products. Although standard analyses exist that predict the distortion of a signal plus a uniform distribution of noise,¹ the same methods are intractable when used with many input signals, A model of dipping distortion that predicts total distortion as a function of the rms modulation depth μ does not take the overall spectral shape or the individual lines into account, hindering comparison to experimental results.² More recent publications have either avoided describing the spectral lines or have included them in ad hoc measurements. We have investigated the clipping distortion in CATV lightwave systems through experimental measurements and computer simulations, and have developed a model from basic principles that describes the distribution of distortion power among the intermodulation spectral lines. The model has excellent agreement with both experiments and computer simulation (see Fig. 1) for second- and third-order distortions, as well as the total intraband distortion. Results are easily extended to other forms of nonlinearity in lightwave systems, such as limiting and imperfections in component L-I curves, etc.

© 1992 Optical Society of America