Coherent Beam Combining of Mid-IR Lasers

Many military applications require efficient optical sources producing several to hundred watts in continuous-wave (CW) or quasi-continuous-wave (QCW) operation at room temperature (RT) in the MWIR (3-5 micron) and LWIR (8-12 micron) regions. While QCLs have become the sources of choice in these spectral regions, the only realistic option to attain hundred-watt power level with good beam quality is to coherently combine multiple QCL emitters into a single output beam. In Phase I, we have performed analysis of QCL arrays, and showed that this approach is well suited for necessary power scaling. We have developed a design, which should produce 10 W of output power at RT. In Phase II, we will develop the processing required for the fabrication of such arrays, fabricate and characterize prototype devices. We will design, fabricate, and characterize a second generation of devices with higher output power of several tens of watts. Furthermore, we will develop a plan for extending the performance of these arrays up to 100 W. Our approach, leveraging advanced material growth and fabrication, will result in robust, compact, and cost-effective monolithic QCL beam combining solutions exceeding the requirements of this solicitation, and provide the military with the required laser sources.