Efficient generation of coherent blue and green light in KTiOPO/sub 4/ crystals

We have investigated second-harmonic generation (SHG) in short-period periodically poled bulk and waveguide potassium titanyl phosphate (KTP) crystals to generate blue light using subpicosecond laser pulses in the forward configuration. The highest conversion efficiency is about 32%. We have also generated blue light due to completely quasi-phase matched cascaded SHG and sum-frequency generation (SFG) in periodically-poled waveguides.