Intensity modulation and noise characterization of high-speed semiconductor lasers

Several properties of lasers used in high-speed optical transmission systems are described. The characteristics of the modulation bandwidth transfer function and the relaxation oscillation frequency, and factors that must be optimized to maximize the modulation bandwidth, are examined. The intensity noise spectral characteristics and the relationship to the modulation bandwidth are determined. The relative intensity noise (RIN) of the laser is defined, and its relationship to the laser transmitters signal-to-noise ratio is noted. Techniques to measure these laser characteristics are reviewed, along with some measurement limitations. Sample measurements of the modulation response intensity noise, and RIN of a 1300-nm DFB laser using the HP 71400 lightwave signal analyzer are shown.<>