High Power, High Efficiency Diode Sources for Pumping Eye-Safe Solid State Lasers

High power eyesafe lasers are crucial for many military and industrial applications. Erbium doped lasers offer the potential for direct laser operation at 1.5 microns thereby reduces the size and cost and improving the efficiency of today' frequency converted one-micron lasers. Diode pumped Erbium lasers are typically pumped at 980-nm. The large quantum defect between the lasing wavelength and the pump wavelength leaves roughly 30% of the deposited energy as heat. For example, a 1-kW Erbium laser would require at least 500 Watts of heat to be removed. This amount of heat not only effects laser performance, it also requires a large thermal management system that adds size, weight, and cost to the system. A similar laser that was pumped at 1470-nm would require a factor of ten less heat to be removed. Unfortunately, today's high power InP diode lasers operating at 1470-nm produce less power and are less efficient 980-nm laser diodes. This is primarily a result of a dramatically lower differential quantum efficiency that results from both lower injection efficiency and higher optical losses. With a novel epitaxial structure we propose to improve the overall efficiency of high power 1470-nm InP based laser diodes to over 40%.