Characteristics of laser diode bar and stack with jet-type, water-cooled heatsink

Our group has developed a funryu ("fountain flow" in Japanese) heatsink structure for a 1 cm laser diode (LD) bar. The funryu heatsink is only 1.1 mm in thickness and is designed in stackable form. With the help of a good indium soldering technique and detailed thermal analysis, this device achieved a thermal resistance of only 0.25°C/W, defined by the temperature increase per unit of heat dissipation. This thermal resistance is one of the lowest ever attained by a laser diode bar. By stacking 30 LD bars equipped with these funryu heatsinks, we achieved a CW output power of 2.3 kW from a 10 mm×45.8 mm laser-emitting area within the stacked-LD module. This power intensity corresponds to 502 W/cm2.