Highly Reliable, High Power Cryogenic Red Diode Lasers

This Phase I Small Business Innovation Research project is aimed at modeling and designing a cryogenic high power red diode laser array for use in optically pumping 100 kW level cryogenic lasers for missile defense and other applications. It is advantageous to operate lasers at cryogenic temperatures because in this environment they have greatly improved heat transfer characteristics, reduced laser thresholds, and increased device reliability. Phase I will develop a conceptual design for cryogenic 630 nm diode laser bars, consisting of individual emitters with output in excess of 0.5 W per emitter. The design will include the epitaxial layer structure, the individual emitter structure, the laser bar geometry, laser bar mounting onto laser headers, laser bar combining into multi-bar laser arrays, and heat spreader design. Mathematical models will be established, and design tradeoffs will be studied to predict device performance and performance limits. A plan for laser array performance measurement will be prepared, and preliminary experimental data will be obtained. Spire has extensive prior experience with high power diode laser array bar fabrication and multi-bar array manufacturing, and is currently manufacturing red LED and red laser products using in-house designed and MOCVD-grown epitaxial wafers in its state-of-the-art semiconductor manufacturing foundry.