NON-CRITICALLY PHASE-MATCHED CASCADED THG AT 440 NM IN KTIOP1-YASYO4 CRYSTALS

We report the relative nonlinear optical properties of flux-grown KTiO P1-yAsyO4 crystals (y = 0, y = 0.03 and y = 0.12). The non-critical ph ase-matching temperatures along the x-axis for blue generation by type II indirect third harmonic generation from 1318.8 nm and 1320 nm are measured. The phosphorus-arsenic substitution allows a ''chemical tuni ng'' of the phase-matching properties, through a birefringence variati on, so that non-critical phase-matching at room temperature is possibl e for the previous interactions. Type II frequency doubling from 1064 nm is briefly considered.