Clipping limit in externally modulated lightwave CATV systems

We have obtained analytic expressions for the composite triple beat distortion of several types of linearized externally modulated systems and compared them both to a directly modulated ideal laser and to a two-level limiter. We used the harmonic analysis method to analyze the cases of (1) a conventional Mach Zender interferometer (MZI), (2) an optically cancelled dual-stage cascaded MZI, and (3) an optically cancelled dual-stage parallel MZI.