Temperature dependence of mode distribution, intensity noise, and mode-partition noise in subcarrier multiplexed transmission systems

Low-frequency intensity noise generated by Fabry-Perot lasers, which is frequency translated inband by subcarrier modulation and enhanced by dispersion, limits transmission of video signals in subcarrier multiplexed systems. This noise is highly dependent on mode distribution and varies dramatically with temperature. A correlation between low-frequency intensity noise, frequency translated intensity noise, mode-partition noise, and mode distribution is demonstrated. Mode distributions are identified which yield very low or very high levels of noise. Tight control of laser temperature and bias current is required to maintain minimum noise levels in subcarrier transmission systems.>