A corrosion and erosion protection coating for complex microchannel coolers used in high power laser diodes

With efficiencies in the range of 50-75%, significant amount of waste heat is generated during the operation of high power laser diodes. In order to maintain consistent optical performance, the temperature of the laser diode needs to be managed effectively. Single phase copper microchannel coolers (MCC) with high purity and low electrical conductivity de-ionized water (DIW) at high velocities are used to dissipate the heat. Though thermally beneficial, the high velocity, high purity DIW coolant exposes the copper MCC to erosion and corrosion damage [1]. This substantially decreases the thermal performance of MCC and requires costly replacement within a short duration. This paper presents the experimental validation of a new vapor deposition coating, developed by Advanced Cooling Technologies, Inc., (ACT) for enhanced protection of MCCs in high power laser diode systems. MCC samples with coating were exposed to accelerated erosion and corrosion testing in high velocity, high purity water that simulates laser diode operating conditions. Evaluation of thermal resistance, pressure drop, and optical properties of MCC stacks demonstrated significant improvements in erosion/corrosion protection provided by the coating without impeding the cooling performance of the MCCs. Hence, the coating will increase the lifetime of MCCs and reduce costly maintenance intervals.