J. Minch et al., THEORY AND EXPERIMENT ON THE AMPLIFIED SPONTANEOUS EMISSION FROM DISTRIBUTED-FEEDBACK LASERS, IEEE journal of quantum electronics, 33(5), 1997, pp. 815-823
The amplified spontaneous emission (ASE) of a strained quantum-well di
stributed feedback (DFB) laser biased below laser threshold is used to
extract the gain and refractive index spectra in a systematic manner,
A modified Hakki-Paoli method is used to obtain the gain and differen
tial gain spectra, The refractive index change due to carrier injectio
n is obtained from the shift of the Fabry-Perot peaks in the ASE spect
rum, The measured ASE spectrum, gain, refractive index change, and lin
ewidth enhancement factor are then compared with our theoretical model
for strained quantum-well lasers, Our model takes into account the re
alistic band structure and uses the material and quantum-well dimensio
ns directly in the calculation of the electronic and optical propertie
s. The theory agrees very well with the experiment.