INVESTIGATION OF THRESHOLD TRANSITION IN SEMICONDUCTOR-LASERS

Semiconductor laser threshold transition is investigated by high preci sion power and linewidth measurements giving specific behavior of line width at threshold depending on linewidth enhancement a factor. An ana lytical model based on Fokker-Planck equation resolution is proposed f or extraction of major laser parameters by fitting simultaneously belo w and above threshold behaviors, Parameters are extracted for two sing le-mode semiconductor lasers with different detunings, Comparison with a threshold adapted rate equation model shows identical asymptotic be havior (Schawlow-Townes) for both models but simpler calculations and higher precision at threshold are obtained with the Fokker-Planck meth od, Detailed investigation of laser phase transition can profit microc avity and surface-emitting laser development by giving unique insight on spontaneous emission evolution and precise noise models.