The main feature of a semiconductor (alpha) -laser is the codirectional small angle Bragg-reflection in a medium with gain. Within the framework of the coupled wave formalism for Bragg reflection an asymmetrical filtering characteristic occurs in dependence on the coupling constant, the ground gain and the gain coupling coefficient. The asymmetric far- field distribution of (alpha) -lasers is comparable with that filtering process.
"Assymmetry of the α-laser emitted in far-field radiation", Proc. SPIE 3737, Design and Engineering of Optical Systems II, (27 August 1999); doi: 10.1117/12.360039; https://doi.org/10.1117/12.360039