Highly Efficient, Power-Scalable Long-Wavelength Diode Laser Pumps for Eye-Safe Solid-State Laser Development

For this SBIR program, Princeton Lightwave Inc. proposes the development of 1530 nm InGaAsP/InP laser diode pump arrays with powers in excess of 50 W from 1-cm bars with the potential for scalability to a two-dimensional bar stack format without limitation in the number of one-dimensional array elements. For use in pumping eye-safe Er:YAG solid state lasers (SSLs) emitting at ~1620-1640 nm, these arrays will be designed to achieve at least 80% photon absorption by the group of Er lines at ~1530 nm in Er:YAG solid state laser gain media and in excess of 90% coupling efficiency with collimating microlenses. Highly effective thermal management will be developed using both optimized microchannel coolers and an innovative evaporative spray cooling system that will also be designed for scalability to support very high power 2D bar stacks (in excess of 500 W). We will build on our existing extremely reliable (>1E6 hours) InP-based low beam divergence pump laser platform that has already demonstrated 42 W CW operation from 1-cm arrays with nearly 34% conversion efficiency at maximum power. Arrays developed for this program will provide unprecedented performance for eye-safe diode-pumped SSLs as well as for direct diode use.