Efficient Power-Scalable and Diffraction-Limited GaAs Diode Lasers

Diode lasers now deliver very high powers at high efficiency, with ~70% electrical-to-optical conversion efficiency demonstrated by several groups from bars with powers of 100 W or greater. However, these devices are incoherent, multi-mode sources that cannot be focused effectively on a distant target and are not suitable for use as a directed energy weapon. Current directed energy designs rely on the use of “brightness converters” – the light from such high efficiency diodes is used to pump another laser medium with high quality single mode output, such as rare earth doped solid-state crystals, glass fibers, and complex flowing alkali gas cells. These brightness converters add cost and complexity and sacrifice efficiency – wasting 50% or more of the injected diode laser energy by turning it into heat. The ideal situation would be to eliminate the brightness converter and use diode lasers directly. This would enable high energy laser (HEL) systems with dramatically reduced cost, size, weight, and power (C-SWAP) requirements. A significant increase in the reliable power, efficiency, and beam quality of diffraction-limited semiconductor lasers is necessary to enable HEL systems based on direct diode technology. In this effort, Freedom Photonics will design, fabricate, characterize, and deliver arrays of high power, high efficiency diffraction-limited diode lasers based on our novel tapered laser technology. These diode arrays may be used as a building block for kW-class direct diode high energy laser systems. Approved for Public Release | 22-MDA-11102 (22 Mar 22)