The influence of phase modulation characteristics on Combined Amplitude-Phase Shift code performance is investigated both experimentally and by simulation. The interferometric push–pull Mach–Zehnder modulator and the linear Phase Modulator are evaluated when the optimal optical Gaussian filter is exploited. Non-optimal optical filter shape and bandwidth are considered as well. The figure of merit is the maximum distance bridged without optical dispersion compensation on a Standard Single Mode Fiber (SSMF) link. The steepness of phase transitions is critical in determining the performance of the generated CAPS
