Passively cooled pump signal combiners at 2.1 kW for fiber laser and amplifier systems

In this work we demonstrate, a high brightness, high transmission Pump Signal Combiner (PSC) operating at 2.1 kW for 10 minutes mounted on a metal plate without running cooling water (Passively Cooled). The 6+1 to 1 PSC tested in this work has six 247 μm cladding diameter 0.22NA pump pigtails, a 10/125um signal pigtail and a 20/400um double clad output fiber. The combiners achieve a high pump transmission efficiency of 98%. During the passively cooled highpower test conducted at a power of 2.1 kW the maximum temperature recorded on the surface of the package was at a temperature of 38.5°C for 10min of power aging.