G. Marnier

Repetition rate dependence of gray-tracking in KTiOPO4 during second-harmonic generation at 532 nm

The aim of this work is to study gray tracking during type II second-harmonic-generation 1064→532 nm in halide flux grown KTiOPO4 crystals. The repetition rate of the laser varies from 1 to 20 kHz. We experimentally demonstrate that the gray-tracking threshold, expressed by the harmonic peak power density, is a decreasing exponential function of the Q-switch frequency. The corresponding 532 nm average power density, however, remains constant.

Absolute measurement of quadratic nonlinearities from phase-matched second-harmonic generation in a single KTP crystal cut as a sphere

We determine within an accuracy of ∼10% the absolute magnitude of the quadratic effective coefficients of types I and II phase-matched second-harmonic generation from conversion efficiency measurements in a single nonlinear crystal cut as a sphere. The agreement is good with measurements performed in thin parallelepipedal samples. The material studied is KTiOPO4, for which improved Sellmeier equations are given.

Phase-matching measurements and Sellmeier equations over the complete transparency range of KTiOAsO 4 , RbTiOAsO 4 , and CsTiOAsO 4

The sphere method is used for the direct measurement of sum- and difference-frequency generation phase matched in the principal planes of KTiOAsO4, RbTiOAsO4, and CsTiOAsO4, including the tuning curves of 1.064-µm-pumped OPO’s emitting between 3 and 5 µm. The nonlinear least-squares fitting of our experimental data leads to refined dispersion equations of the principal refractive indices; the resulting dual-oscillator form equations are valid over the complete transparency range of the three studied materials.

Methodology for optical studies of nonlinear crystals: application to the isomorph family , , and

We develop a methodology for the measurement of quadratic nonlinear optical properties of crystals. Our methods are mainly based on the use of the spherical geometry which allows, with only one crystal, accurate measurements of the phase-matching directions and the associated angular acceptances, double-refraction angles and effective coefficients. These data constitute a reliable basis for the modelling of the second-order electric susceptibility of crystals and for the comparison between materials.

Cubic optical nonlinearity of

We perform angular non-critical phase-matching third-harmonic generation (THG) experiments in (KTP). From these experiments, we determine the magnitude and sign of the two phase-matched nonlinear coefficients of by a complete analysis of phase-matching properties of the cascaded quadratic and pure cubic processes, the resolution of the coupled propagation equations and by the calculation of the quadratic and cubic dielectric susceptibility tensor by an extended bond charge model; we find: and . We also demonstrate that the two studied THG are mainly governed by the cubic interaction.

Optimized blue light generation in optically contacted walk-off compensated RbTiOAsO4 and KTiOP1−yAsyO4

Abstract We study type II 1.32 μm second harmonic generation (SHG) in a RbTiOAsO 4 optically contacted walk-off compensated device. The reduction of the effective walk-off angle by a factor of 3.7 with respect to KTiOPO 4 for the same interaction leads to an enhancement by a factor of 10 of the conversion efficiency. A model is proposed for both type I and type II SHG in such a structure. The angular tuning curve is a multi-peaked one, as predicted by the model. The enhancement of the SHG conversion efficiency allows us to optimize the generation of blue laser light at 440 nm: a specially designed KTiOP 0.98 As 0.02 O 4 solid solution crystal achieves angular non-critical phase matching at room temperature for type II sum frequency generation 1.32 μm+0.66 μm→0.44 μm.

Non-critically phase-matched cascaded THG at 440 nm in KTiOP1−yAsyO4 crystals

Abstract We report the relative nonlinear optical properties of flux-grown KTiOP 1− y As y O 4 crystals ( y =0, y =0.03 and y =0.12). The non-critical phase-matching temperatures along the x -axis for blue generation by type II indirect third harmonic generation from 1318.8 nm and 1320 nm are measured. The phosphorus-arsenic substitution allows a “chemical tuning” of the phase-matching properties, through a birefringence variation, so that non-critical phase-matching at room temperature is possible for the previous interactions. Type II frequency doubling from 1064 nm is briefly considered.

Refined Sellmeier equations from phase-matching measurements over the complete transparency range of KTiOAsO 4 , RbTiOAsO 4 and CsTioAsO 4 .

Sum- and difference- frequency generation phasematching properties are measured in spheres of KTiOAsO4, RbTiOAsO4 and CsTiOAsO4 for Sellmeier equations refinement over their complete transparency range.