High-power and reliable operation of window-structured 915 nm laser diodes with 90 μm aperture

Summary form only given. High power broad-area laser diodes at 9xx-nm have been widely employed in many industrial applications including direct material processing and pumping fiber lasers and solid state lasers [1,2]. 915-nm broad-area laser diodes with stripe widths (apertures) ranging from 90 to 100 μm are an attractive candidate as a pumping source for the fiber lasers. A major issue of the high power laser diodes is catastrophic optical mirror damage (COMD), which is caused by the facet heating due to optical absorption. So far, various approaches to suppress COMD have been studied and developed. Among them, a window structure formed by impurity-free vacancy disordering (IFVD) is considered to be the most promising approach because it retains crystalline quality and low optical propagation losses [3,4]. The degree of quantum well intermixing by IFVD can be estimated by the band gap difference (ΔEg) between the window region and the gain region. Although there has been considerable interest in the relation between the characteristics of laser diode and the ΔEg, there have been no reports on that point.In this work, we have achieved a 15 W reliable operation of 915 nm broad-area laser diodes with a stripe width of 90 μm by optimizing the window structure. This is the first report on the optimization of the band gap difference for a high power broad-area laser diode at 9xx-nm.