2.3 Micron High Power Continuous Wave Diode Laser Arrays

High power semiconductor lasers emitting around 2.3 microns have many military and commercial applications. Particulary interesting is the potential use of these devices as pump sources for optically pumped semiconductor lasers emitting in the 3-5 micron range. Having successfully developed the world's first high power 2.3 micron laser arrays in Phase I of this STTR, we seek to improve on the output power, wall plug efficiency, and beam quality of the devices. We describe device improvements that will increase the wall plug efficiency by a factor of four to approximately 35%, and will increase the bar output power to 30 W in CW operation. Quasi-CW pulsed mode output power will be close to 50 W with the proposed designs. These considerable improvements will be based on our Phase I experimental results. We have identified improvements that can be made through control of lateral current spreading, reduction of waveguide losses by changes in waveguide design, and an increase in injection efficiency through changes in the composition, geometry and doping of the waveguide. Many of the improvements address the issue of excess voltage drop across our Phase I structure. We propose changes to the waveguide and heterointerfaces that will substantially decrease the excess voltage drop.