Correlation of spectral output and below-threshold gain profile modulation in 1.3 μm semiconductor diode lasers

A residue which is characteristic of internal scattering is extracted from the below threshold spectra of 1.3 μm semiconductor diode lasers by fitting a smooth function to the measured gain profile. The residue is found to be correlated with the above threshold spectral output. This suggests that the amount of scattering in the active region is an important quantity in determining the spectral output of semiconductor diode lasers.