R. Kremer

Implanted waveguides in borate crystals (LTB, β-BBO, and LBO) for frequency conversion

Abstract Helium implantation is used to produce optical waveguides in LTB, β-BBO and LBO materials. These waveguides present a step index behavior revealing a good optical quality of the guiding region with losses in the range 2–5 dB cm−1. The annealing process at 200°C during 2–24 h showed a good stability of the guiding region with a slight decrease of the optical losses. Preliminary results of SHG in LBO:He+ waveguides are reported.

Effective nonlinear coefficients of organic powders measured by second-harmonic generation in total reflection: numerical and experimental analysis

A second-harmonic wave generated by an evanescent wave (SHEW) is used to measure the effective nonlinear coefficient of organic materials in powder form. The SHEW signal is less sensitive than the powder method to the phase-matching conditions of the material. For this reason, the SHEW technique can be used to survey a wide variety of samples. The effective nonlinear coefficient and the refractive indices of the sample are obtained as fitting parameters. The influence of experimental conditions on the fitting process is discussed. The results obtained from our powders are compared with the nonlinear coefficients of the same materials in bulk crystal form. Good agreement is found between experimental results and literature values.

Linear and nonlinear optical properties of implanted Ca4GdO(BO3)3 planar waveguides

We report on a detailed investigation of optical planar waveguides fabricated in the new nonlinear Ca4GdO(BO3)3 crystal by ionic implantation. Both single and multiple He+ implantations are investigated. Second-harmonic generation (SHG) in He+ multiple-implanted samples are achieved by type I phase matching for fundamental light propagating along the y axis and polarized along the z axis at 823 nm and for light propagating along the x axis and polarized along the z axis at 960 nm. SHG operates with low-power pumping of a cw Ti:sapphire laser. Analyses of SHG within the waveguides are presented. The results indicate that the nonlinearity of the material remains in the guiding area after ion implantation. The conversion efficiency was found to be ∼10−2. This value is increased by ∼10% after 1 h annealing at 220°C.

Frequency doubling in He/sup +/-implanted periodically poled lithium niobate waveguides

Frequency doubling has been successfully performed in helium implanted planar waveguides in periodically poled lithium niobate by using quasi phase matching to generate blue laser beams.