Abstract

Efficient power scaling of ~ 10 ps pulses at 1342 nm wavelength is important for selective scribing of thin film copper InGaSe solar cell (CIGS). Processing speed is defined accordingly by average output power and pulse repetition rate. Despite sufficient stimulated emission cross section in Nd:YVO₄ at 1342 nm wavelength, 1.65 times large quantum defect and higher energy transfer upconversion are expected in comparison with traditional 1064 nm wavelength. The known approaches to manage thermo-mechanical problems include bounce slab geometry [1], longer rods with lower Nd doping [2], pumping at 880 nm absorption band [3] and composite rods with varying Nd concentration [4,5]. Power scaling in the end pumped amplifiers [2-5] is limited by thermal effects which are substantially aggravated by inhomogeneous pump distribution along the laser crystal. A great variation of the absorption factor within the pump linewidth (Δλ = 3 – 5 nm for regular laser diodes of 100 W power) and absorption anisotropy lead to strong excessive pumping of the laser rod entrance resulting in severe rise of crystal temperature and stress. These effects are substantially reduced for 888 nm absorption line having broadband and nearly isotropic absorption [3].

© 2015 IEEE