MODEL OF THE SPECTRAL OUTPUT OF GAIN-GUIDED AND INDEX-GUIDED SEMICONDUCTOR DIODE-LASERS

A model for predicting the longitudinal-mode spectra of semiconductor diode lasers is presented. The model considers the effects of experimentally observed scattering, which exists in or near the active region. By changing the amount of scattered light and the location of the scattering center, one can predict theoretical longitudinal-mode spectra to be multimode, single mode, asymmetric, or double gain peak. Thus the model, coupled with the observed scattering properties of index-guided and gain-guided lasers, provides an explanation of why gain-guided lasers tend to operate more multilongitudinal-mode than do index-guides lasers.