Quantum Dot Gain Material for High Reliability, Radiation-Hard Laser Diode Pump

ABSTRACT: A new active material will be developed and tested to improve reliability for space applications. Recent improvement in facet reliability reveals that bulk failure mechanisms could limit laser diodes used in space. Radiation-induced defects are expected to occur in the bulk of the laser diode gain material because of its active volume. The new active material is designed to limit internal heating at defects, and reduce the average junction temperature relative to the heat sink temperature. Preliminary studies on cleaved facet laser diodes indicate that with further improvement in active material quality, high quality facet coating, and high quality heat sinking, power and efficiency could reach or exceed commercial laser diodes. A Phase I is proposed to optimize the gain material and waveguide design to produce prototype devices for detailed reliability and radiation studies in a Phase II. Full optimization of the active material physics could produce laser diodes with electro-optic properties superior to commercial laser diode pumps. The combined improvements in bulk reliability and electro-optic performance could lead to rapid commercialization into the military and industrial laser diode markets. BENEFIT: The current commercial high power laser diode technology is highly developed and only incremental improvements are expected by maintaining the current active material and device designs. Many military applications can benefit from higher powers that could be possible by introducing new designs. These new designs should produce higher reliability, less susceptibility to radiation induced-defects for space applications, and lower internal optical loss to give the potential for higher power and efficiency. The new materials to be researched and developed in this research effort can bring these advantages by changing the internal laser device physics from the current planar quantum wells.