56 Gb/s 20-km Transmission of PAM-4 Signal Employing an EML in C-band without in-line Chromatic Dispersion Compensation

We experimentally demonstrate 56 Gb/s PAM-4 transmission using a 1.55-micrometer EML over a 20-km SMF maximum reported distance without employing DCFs in the link, for low-cost metro and short-reach WDM applications. Performance is optimized and compared for various DSP schemes.