Progress in Long-Wavelength High-Power Diode Laser Pump Sources

摘要

A variety of applications are driving development of high-power laser diodes operating between 1.4 and 2.1 μm . For example, Er-doped solid state and fiber lasers offer "eye-safe" alternatives to Nd-and Yb- doped lasers for use in military and industrial applications including range-finding, illumination, flash/scanning LADAR, and materials processing. Due to a reduction in quantum defect, direct diode pumping of Er lasers around 1.5 μm offers the potential for greatly increased system efficiency, reduced system complexity/cost, and further power scalability [1-2]. As another example, military, space, and medical applications benefiting from emission around 2.1 μm are driving development of Ho:YAG solid state lasers [3]. Efficient pumping of these systems can be achieved through direct diode pumping at 1.9 μm [4]. In this work, we describe recent progress in the development of high-power long-wavelength diode laser pump sources. 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. These modules can be efficiently fiber-coupled or be configured to provide a high-brightness collimated output. In this format, rated power in excess of 50 W and conversion efficiency in excess of 30% are reported for 1470-nm modules operating continuous wave (CW) at 25 ℃; rated power in excess of 18 W and conversion efficiency in excess of 10% are reported for 1900-nm modules operating CW at 25 ℃.