Probability distribution of phase-induced intensity noise generated by distributed-feedback lasers

Highly non-Gaussian, short-tailed photocurrent distributions due to laser-phase-induced intensity noise have been observed in fiber-optic systems employing distributed-feedback lasers and wideband receivers. This behavior, which has implications for the correct prediction of performance in systems containing intentional or spurious interferometers, results from the cosinusoidal nonlinearity introduced by the interference process. The laser frequency noise is thereby converted to non-Gaussian intensity fluctuations at the system output. The intensity-noise statistics rapidly revert to Gaussian form, however, in systems whose receiver bandwidth is smaller than the laser linewidth.