Influence of self-phase modulation effect on waveform degradation and spectral broadening in optical BPSK-SSB fiber transmission.

Self-phase modulation (SPM) effect is analyzed in a dispersion-compensated transmission using optical BPSK single sideband (SSB) modulation. The effect was evaluated numerically using both waveform degradation and spectral degradation, clarifying that waveform degradation is induced dominantly by peak power of the quadrature component of a Hilbert-transformed signal. Eye-opening degradation of BPSK-SSB is induced by lower fiber input power than the conventional double sideband (DSB) case because the SSB-homodyne system is sensitive to phase error resulting from SPM. Spectral degradation from SPM has two phases with increasing fiber input power. In the first phase, the sideband in the suppressive frequency region expands with increasing optical power. In the second phase, the spectral envelope in the non-suppressive frequency region becomes broad, and its shape is somewhat varied.