Design optimisation for high-power high-brightness parabolic bow-tie laser diodes

Optical sources that combine high power with high brightness are in great demand for various applications. Although sophisticated device designs have been demonstrated to have such desirable characteristics, in order to contain the device costs, tapered geometry devices seem to provide attractive alternatives. Furthermore, particularly for high-power operation, the bow-tie configuration is effective for further reducing the risk of catastrophic optical damage and for obtaining a good quality output beam. The authors present the detailed analysis that has been necessary to optimise both the material layer structure and the tapered laser geometry to achieve simultaneously high power and high brightness. Following the design guidelines, several 980 nm parabolic bow-tie lasers have been fabricated and characterised in-house, obtaining output powers in excess of 700 mW per facet in a diffraction-limited (2.7°) beam measured without the use of external lenses.