Simple method for determining the gain saturation coefficient of a distributed feedback semiconductor laser

A simple method for determining the gain saturation coefficient epsilon of a semiconductor laser utilizing the injection-modulated pulse therefrom is proposed and demonstrated experimentally. This method is based on numerical fittings for the spectral profile distortion for pulses due to the gain saturation. No other laser to be used to excite the laser under test nor any fast photodetector to detect the pulse is required provided that other characteristic parameter-values are known. Using this method, epsilon value of a 1.55 mu m distributed feedback semiconductor laser is estimated to be 2.0 x 10(-23) m(3).