Multi-Watt Mid-IR Laser Module with Near-Diffraction Limited Output

High power IR lasers are highly useful for DOD applications such as remote chemical sensing, infrared countermeasures, and LADAR. Daylight Solutions proposes to build a prototype system for quantum cascade laser (QCL) beam combining having an output power > 1W and a beam divergence less than twice the diffraction limit. The Phase I prototype will consist of three external cavity QCLs, integrated with a novel high-efficiency beam combiner. This technique, called wavelength beam combining, has found great success in the visible and near-infrared range, and should naturally extend to the mid-infrared regime. This approach eliminates thermal crosstalk while maintaining high power and excellent beam quality. It also allows for optimum propagation through the atmosphere. Since each laser wavelength is controlled by its own external grating, several atmospheric absorption peaks may be avoided by careful selection of individual wavelengths. Phase I will tackle the combination of three lasers. Phase II will handle scaling this up to approximately 10 lasers to achieve > 5W output powers.