Key points are not available for this paper at this time.
The Lorentzian lineshape of a single longitudinal mode AlGaAs semiconductor laser is directly observed by optical heterodyne detection. A remarkable reduction in the spectral linewidth to less than 50 kHz is achieved with external grating feedback. The experimental linewidth is in reasonable agreement with the theoretical value, which is obtained by finesse calculation of the active Fabry-Perot cavity.
Saito et al. (1981) studied this question.