Small-signal analysis of OOFDM signal transmission with directly modulated laser and direct detection

This work presents a small-signal analysis for investigating the transmission performance of optical orthogonal frequency division multiplexing signals with a directly modulated DFB laser (DML). The analysis shows the positive chirp of DMLs can intensify power fading after transmission with positive dispersion and provide power gain instead with negative dispersion. The power of subcarrier-to-subcarrier intermixing interference after square-law direct detection, however, is independent on the sign of dispersion.