High-power diode lasers operating at 1800-2100-nm for LADAR and direct use in IRCM applications

A variety of applications are driving development of high power laser diodes operating between 1.8 and 2.1 μm. For example, military and space LADAR applications benefiting from low atmospheric absorption around 2.1 μm utilize Ho:YAG solid state lasers. Efficient direct diode pumping of these systems can be achieved with diode lasers operating around 1.9 μm. As another example, high power diodes operating at >2 μm are suitable for direct use in laser-based infrared countermeasure (IRCM) systems. In this work, we describe recent progress in the development of high-power long-wavelength diode laser sources. For applications requiring high brightness, nLIGHT has developed a conductivelycooled package format, possessing a footprint the size of a typical business card, which is based on scalable arrays of single-emitter diode lasers which can be efficiently coupled into a 400 μm core fiber. Under a NASA-funded SBIR contract, rated QCW powers in excess of 25 W are reported for modules operating at room temperature around 1900-nm. At 2050-nm, room-temperature QCW power in excess of 20 W in the same format is also demonstrated. In copper microchannel-cooled cm-bar format, we demonstrate greater than 37 W peak power and 23% peak conversion efficiency at 1900-nm and 25 W at 2050-nm.