Packaging of high power semiconductor laser arrays using a novel macro-channel cooler

Abstract

High power semiconductor laser arrays have been widely used in many fields, such as pumping solid state laser aerospace, industry, medicine and display. For many applications, high power semiconductor lasers operating quasi-continuous wave (QCW) mode are demanded. For QCW laser, the output peak power is higher and average power is low. Therefore, the transient thermal density is very high. The most common method of removing the large amounts of waste heat in a semiconductor laser package is by using commercially-available copper micro-channel coolers (MCC). However, due to the coefficient of thermal expansion (CTE) mismatching between copper and laser chip, hard-solder cannot be directly used. On the other hand, indium solder has the problem of electro-thermal migration when the temperature grads were high in QCW mode. Furthermore, copper material is susceptible to erosion and corrosion. To overcome these hurdles in many applications, a novel macro channel cooler (MaCC) was presented in this work. The thermal behavior of MaCC-packaged high power semiconductor laser arrays in QCW mode was studied using finite element analysis (FEA). A high power of >250W QCW semiconductor laser array/bar using hard solder was fabricated. The performances of laser arrays, including output power, slope efficiency, threshold, conversion efficiency, spectral width, near field, lifetime etc. were characterized. The measured results indicated that the output power of a MaCC- packaged high power semiconductor laser array was very close to that of copper micro-channel cooler. Based on MaCC-packaged single laser array/bar, multiple-bar stack and two dimension area array lasers with output powers of several kilowatts and several tens of kilowatts were fabricated.