Coupling system for laser-diode-array end-pumped slab amplifiers

A coupling system with a high contraction coefficient, up to 86∶1, has been designed and manufactured. The output from the spherically arranged 80 kW LD arrays is delivered by orthogonal cylindrical lenses and a hollow duct. Experimentally measured coupling efficiency of the system is 84.2%. Intensity modulation values of the pump-field at the exit are 1.30 of LD fast axis and 1.18 of LD slow axis. The pump light can transport a distance of 8.5 mm at least with its shape preserved. The coupling system can meet the requirements of end-pumped slab amplifiers for high pump power and pump power density.