End-pumped coupling system based on large-aperture laser diode array

In order to meet the pump power density requirements of room-temperature Yb: YAG laser amplifier, a coupling system of high contraction coefficient has been designed. Laser diode (LD) arrays of 80 kW output power are arranged to be spherical. Orthogonal cylindrical lenses and a hollow duct are used for pump-coupling according to luminescence properties of LD. The contraction coefficient is up to 86∶1. Simulations show that the coupling efficiency of the coupling system depends weakly on the reflectivity of the reflectors of the hollow duct. The pump light can transport over a distance of at least 8.5 mm with its shape maintained. The coupling system can meet the requirements of the end-pumped room-temperature Yb:YAG slab amplifier.