A heat exchanger package has been demonstrated for semiconductor laser arrays using silicon microstructures with water as the coolant. A thermal impedance of 0.04 °C cm2/W has been achieved for a single linear bar. This design makes use of efficient, edge-emitting laser diode arrays in a rack and stack architecture combined with a high-performance silicon microchannel structure to allow cw operation. The architecture can be scaled to large areas and we project a thermal impedance of 0.09 °C cm2/W for close-packed two-dimensional arrays on this device.
We have demonstrated high average power output devices in both one-dimensional (1-D) and two-dimensional (2-D) arrays of laser diodes using efficient edge emitting cleaved bars and silicon microchannel coolers. These packages are based on the rack and stack architecture. For the 1-D array a cw optical power output of 22.2 W was obtained with 20% electrical to optical conversion efficiency. For the 2-D array an average optical power density of greater than 100 W/cm2 was obtained at an efficiency of 25%.
Many applications for semiconductor lasers that require high average power are limited by the inability to remove the waste heat generated by the diode lasers. In order to reduce the cost and complexity of these applications a heat sink package has been developed which is based on water cooled silicon microstructures. Thermal resistivities of less than 0.025 °C /(W /cm2) have been measured which should be adequate for up to CW operation of diode laser arrays. This concept can easily be scaled to large areas and is ideal for high average power solid state laser pumping.Several packages which illustrate the essential features of this design have been fabricated and tested. The theory of operation will be briefly covered, and several conceptual designs will be described. Also the fabrication and assembly procedures and measured levels of performance will be discussed.
A simple and highly reliable package consisting of a 1-cm-long AlGaAs laser diode array mounted directly on a silicon microchannel cooler has been demonstrated. 3.4×109 shots were logged on this device at an average optical output of 8.75 W with only a 6% increase in current required to hold the light output constant. This extrapolates to a current doubling lifetime of 1.6×1011 shots. The thermal impedance was also measured to be 0.014 °C/(W/cm2).
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AbstractDetailed performance results and fabrication techniques for an efficient and low thermal impedance laser diode array heatsink are presented. High duty factor or even CW operation of fully filled laser diode arrays is enabled at high average power.
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