Potassium titanyl phosphate thin films on fused quartz for optical waveguide applications

Thin films of potassium titanyl phosphate (KTiOPO₄) for photonic applications have been fabricated on fused quartz substrates by pulsed excimer laser ablation. The textured films were optically uniaxial with the symmetry axis oriented normal to the film surface. The principle component of the second order electric susceptibility was oriented parallel to this symmetry axis and was determined to be about 16 times the magnitude of quartz for the fundamental wavelength of 1.064 μm. This configuration, with the largest nonlinear optical response for polarizations perpendicular to the film surface, is desirable in TM guided wave applications. Planar optical waveguide measurements were performed and the linear waveguide loss was measured. The frequency dependence of χ⁽²⁾(ω) was determined and found to be uniform for visible second harmonic wavelengths.