Research on high brightness fiber coupled diode laser module with hundred watts class output power

Three 976 nm diode laser short bars were used as submodule to manufacture high brightness fiber coupled module with CW hundred watts class output power. First, beam transform systems were employed to shape beams emitted from each submodlue; Second, the three beams were stacked in direction of lower beam parameter product by means of spatial multiplexing technology; Finally, the laser was focused into a multimode fiber with 200 μm core diameter and NA=0.22 by optimized lens. Experiment result showed that divergence angle of the focused laser beam was 24.8° and its beam waist diameter was 175.2 μm; laser output from fiber could reach to 107 W, equalizing brightness of 2.23 MW/(cm ²·sr), which is a higher level in China. Furthermore, the wall plug efficiency is 43.1% when driving current is 52.5 A, which is far higher than that of solid state laser. Finally the thermal resistance was computed by means of measuring spectrum with different current and the result is 1.29 K/W which indicates favorable heat dissipation of the module. All of the result showed that the module can be used in the field of pumping fiber lasers, medical, material processing and so on.