Refractive dispersion curve measurement of KTiOPO4 using periodically segmented waveguides and periodically poled crystals

We introduce a technique for measuring the refractive indices of a crystal and apply it to measure the dispersion curve of KTiOPO4. The refractive index evaluation is based on measurement of the Bragg reflection wavelength of periodically segmented waveguides close to cut-off conditions. The measurement error is found to be less than 10−4. Second harmonic generation and optical parametric oscillation in periodically poled KTiOPO4 enable us to extend the measurement to a wide wavelength range. A room temperature Sellmeier type equation for the dispersion curve nz(λ) of flux-grown KTiOPO4 in the entire transparency range of the crystal is determined.