Crystal Growth and Linear and Nonlinear Optical Properties of KIO₃·Te(OH)₆

A single crystal of the nonlinear optical material KIO₃·Te(OH)₆ (KTI) with dimensions of 37 × 7 × 5 mm³ was successfully grown at room temperature by slow evaporation. Linear and nonlinear optical measurements were performed on these crystals. Rocking curve measurements indicate that the single crystal is of high quality with a full width at half-maximum (fwhm) of 0.023° (82 arcseconds) from the (010) reflection. Refractive index measurements revealed a birefringence of 0.0545 @ 1064 nm. Through the refractive index measurements and the fitted Sellmeier equations, we determined the Type I and Type II phase-matching wavelength ranges. KTI is Type I (Type II) phase-matchable with a fundamental wavelength range from 674-3266 nm (880-2260 nm). Powder second-harmonic generation (SHG) measurements indicate an SHG intensity of 1.2× KH₂PO₄ (KDP). SHG coefficients were determined by the Maker fringe method on cut and polished (100) and (010) single crystal wafers. The d₃₁ = 0.24 pm/V and d₃₂ = 0.73 pm/V were determined. Laser damage threshold (LDT) measurements were also performed, which indicates that KTI has an LDT of 731 MW/cm² at 1064 nm with a 6 ns pulse width.