Determination of white and 1/f FM noise components of semiconductor laser spectrum by a delayed self-heterodyne interferometer using short delay fiber

The measurement and evaluation of power spectrum of a semiconductor laser by delayed self-heterodyne interferometer is demonstrated with the use of a short delay fiber. The measured spectrum is analyzed numerically including the effect of a delay time much less than the laser coherence time. The theoretical formulation developed here is found to be accurate since it exhibits a peak with finite width at the center frequency of the measured lineshape. The white and lif components of the laser FM noise are then separated successfully by fitting numerical analysis to the experimental results.