Characterization of optical and nonlinear properties of periodically-poled RbTiOAsO4 in the mid-infrared range via difference-frequency generation

Tunable mid-infrared coherent radiation (3.25- 3.7 μm) is generated by quasi-phase-matched difference frequency generation in a multi-grating periodically-poled RbTiOAsO₄ crystal. The spontaneous polarization and coercive field of flux-grown RbTiOAsO₄ are determined by polarization switching measurements. The nonlinear interaction enables us to explore the optical and nonlinear properties of this material in the mid-infrared range, where data is scarce. The measurements are used to derive a mid- infrared corrected dispersion equation for n_z in RbTiOAsO₄. This equation is in excellent agreement with previously published measurements of nonlinear interactions in periodically-poled RbTiOAsO₄. The measured wavelength and temperature bandwidths are ≈48 nm cm and ≈29 °C cm, respectively. A relatively high temperature tuning slope of the phase-matched idler wavelength, -1.27 nm/°C, is measured. This may be useful for realizing temperature-tuned nonlinear devices. Received: 30 March 2000 / Revised version: 9 May 2000 / Published online: 30 June 2000