High-power diode lasers operating around 1500-nm for eyesafeapplications

摘要

Er:YAG solid state lasers offer an "eye-safe" alternative to traditional Nd:YAG lasers for use in military and industrial applications such as range-finding, illumination, flash/scanning LADAR, and materials processing. These laser systems are largely based on diode pumped solid state lasers that are subsequently (and inefficiently) frequency-converted using optical parametric oscillators. Direct diode pumping of Er:YAG around 1.5 um offers the potential for greatly increased system efficiency, reduced system complexity/cost, and further power scalability. Such applications have been driving the development of high-power diode lasers around these wavelengths. For end-pumped rod and fiber applications requiring high brightness, nLIGHT has developed a flexible package format, based on scalable arrays of single-emitter diode lasers and efficiently coupled into a 400 um core fiber. In this format, a rated power of 25 W is reported for modules operating at 1.47 um, with a peak electrical to optical conversion efficiency of 38%. In centimeter-bar on copper micro-channel cooler format, maximum continuous wave power in excess of 100 W at room temperature and conversion efficiency of 50% at 6C are reported. Copper heat sink conductively-cooled bars show a peak electrical-to-optical efficiency of 43% with 40 W of maximum continuous wave output power. Also reviewed are recent reliability results at 1907-nm.