M. Hochholzer et V. Jordan, DISCUSSION OF THE LINEWIDTH ENHANCEMENT FACTOR-ALPHA OF GAAS GAALAS QUANTUM-WELL LASERS/, IEE proceedings. Optoelectronics, 141(5), 1994, pp. 311-315
The fundamental contributions of optical interband transitions and the
plasma effect of free carriers to the linewidth enhancement factor al
pha of Ga(Al)As quantum well lasers has been discussed with respect to
the dependence on the main laser structure parameters: confinement pr
ofile, number of quantum wells and well width. The results show clearl
y that alpha increases with carrier density. Particularly, in SQW-SCH
laser structures with thin quantum wells, alpha is enlarged drasticall
y by the plasma effect due to the necessary high threshold carrier den
sities. Both, the use of a GRINSCH structure or a MQW laser design red
uce the free carrier component of alpha considerably. Furthermore, onl
y a weak dependence of the alpha factor on the number of quantum wells
is found in the case of MQW lasers. Finally, a comparison of alpha-si
mulations and measurements on SQW-GRINSCH and 3QW-SCH BCRW laser struc
tures shows a good agreement.