Influence of the epitaxial layer structure on the beam quality factor of tapered semiconductor amplifiers

In the last years, very good results have been demonstrated in the field of high power diffraction limited tapered semiconductor lasers and amplifiers. However, to our knowledge, no work was reported on the correlation between the epi-structure and the beam quality. In this paper, we discuss the reasons why different epitaxial layers are not equivalent from the beam quality point of view. We then report measurements made on semiconductor amplifiers of different wafers showing that the choice of the epitaxial structure is crucial to obtain good beam quality.