Mauro Fernandes Pereira,
https://link.springer.com/chapter/10.1007/978-94-024-1093-8_22
The linewidth enhancement (α factor) due to fluctuations in the refractive index induced by carrier fluctuations of intersubband lasers was initially expected to be zero. However, values ranging from −0.5 to 3 have been found experimentally. For laser without inversion conditions, which have potential for the high temperature operation of terahertz lasers, α is found to be larger, but still at the same order of magnitude of conventional inverted medium lasers and this paper further investigates this case for dilute nitride quantum well structures.
