Abstract: Power combiners and associated computer-implemented methods and computer program products are provided. An example power combiner includes a plurality of power input structures each of which defines a waveguide that receives a respective electromagnetic radiation input from a respective power source and a central combining conduit. The central combining conduit receives the respective electromagnetic radiation inputs communicated via respective power input structures and combines the respective electromagnetic radiation inputs into a combined power signal for output via an output port communicably coupled with the central combining conduit. The power combiner may also include a cooling loop configured to dissipate heat from at least one of the power input structures to an external environment of the power combiner.