Simultaneous measurement of the linewidth, linewidth enhancement factor α, and FM and AM response of a semiconductor laser

Using a commercially available computer controlled spectrum analyser with tracking generator, optical input section, and optical delay line it is possible to measure the linewidth, linewidth enhancement factor α, and FM and AM response of a semiconductor laser in one process. The determination of the linewidth yields also information about the frequency noise density and the determination of a delivers information about the nonlinear gain. Assuming an optical input power of 0 dBm, a laser linewidth <50 MHz and a modulation response of the laser without cut-off, AM indices m>0.01% and FM deviations of about >10 MHz up to 20 GHz can be detected