Thermal Management System for Solid State Lasers

Many of the state of the art laser diodes and solid-state lasers currently use cooling systems that are limited to less than 100W/cm2. Significant improvements in the heat flux capabilities of the thermal management system would allow these devices to bemuch more compact. Better cooling and load leveling during periods of peak usage will make these devices suitable for many airborne and/or spaceborne applications. Through the use of advanced high-heat flux cooling techniques, the heat flux can beincreased to 500-1000 W/cm2 enabling significant improvements in the device output power, size and mass. kTC proposes the development of a laser packaging concept combining two innovative technologies: copper encapsulated annealed pyrolytic (APG) and graphite foam. Copper encapsulated APG is a composite material with five times the conductivity of aluminumand will be used as an efficient heat spreader lowering the high flux density to a manageable level. The graphite foam will be attached to the encapsulated APG heat spreader and act as a heat exchanger. Convection coefficients as high as 20,000 W/m2Khave been reported in heat exchangers using graphite foam that is nearly 15 times greater than commercial aluminum fin-plate designs. The laser diode packaging to be demonstrated under this program would have applications in the commercial satellite market, as well as the obvious military and NASA uses. Moreover, as the integration of copper encapsulated APG and graphite foam matures for the packaging of high flux chips, the application will expand to rapidly emerging electric drive and power supply electronic systems. Enabling technologies will allow the increase of production and the realization of economies of scale, facilitatingpenetration of other high volume heat sensitive product markets like personal computers.