Corrections to refractive index data of stoichiometric lithium tantalate in the 5-6 μm range

We propose corrections to the coefficients in the published Sellmeier equation for stoichiometric LiTaO3 [Opt. Lett. 28, 194 (2003)] that allow the extension of the wavelength range within the region of midinfrared absorption edge up to 6 um. The required extraordinary refractive index data for this range were obtained using single-pass optical parametric fluorescence measurements with a pump wavelength of 1064.4 nm. We also observed efficient parasitic second-harmonic generation that could affect some quasi-phase-matching interactions. The corrected Sellmeier equation improves the accuracy of poling period calculations where the idler wavelength is within the region.The authors thank Kenji Kitamura from SWING and Karin Wu from HC Photonics for fruitful discussions. This work was supported by the Australian Research Council (LP0453639)