High-efficiency blue generation by frequency doubling of femtosecond pulses in a thick potassium niobate crystal

Summary form only given. We discuss blue generation by frequency doubling of femtosecond pulses in a thick nonlinear crystal. We achieve high conversion efficiencies up to 75% using low laser powers in a simple apparatus and demonstrate a focusing dependence that deviates significantly from the traditional long-pulse result. We have also observed that the spectral width of the generated blue light can be tuned by more than a factor of five by varying the focusing conditions.