A laser source assembly for providing an assembly output beam includes a first MIR laser source, a second MIR laser source, and a beam combiner. The first MIR laser source emits a first MIR beam that is in the MIR range and the second MIR laser source emits a second MIR beam that is in the MIR range. Further, the beam combiner spatially combines the first MIR beam and the second MIR beam to provide the assembly output beam. With this design, a plurality MIR laser sources can be packaged in a portable, common module, each of the MIR laser sources generates a narrow linewidth, accurately settable MIR beam, and the MIR beams are combined to create a multiple watt assembly output beam having the desired power.