ABSTRACT
This chapter focuses on the impact of external optical feedback on high-brightness laser diodes. It starts by introducing the common beam quality metrics used for lasers and briefly reviews the diode laser technologies most commonly considered for high-brightness direct-diode laser systems, before focusing on the tapered laser and showing why they are strong contenders for future high-power direct-diode laser systems. The purpose of the beam-combining optics in a direct-diode laser is usually to couple the highest amount of power from the individual laser diode sources into the end of an optical fiber. The chapter describes the coupling of continuous wave simulation tool, Speclase, to commercial optical design tools to self-consistently simulate high-brightness diode lasers with external optical feedback. It concludes with a case study exploring the impact of unintentional feedback on the excitation of higher order vertical modes and lateral beam quality in a large optical cavity tapered laser.
