S. Nouh

Modeling and experimental observation of parametric fluorescence in periodically poled lithium niobate waveguides

We present a theoretical and experimental study of parametric generation in a guided wave quasi-phase-matched configuration. A numerical model taking into account inverted domain shape, electrooptic and photorefractive effects, as well as waveguide profiles allows calculation of the observed phase matching curves. The observed parametric fluorescence efficiencies can be explained by assuming a slight reduction of nonlinear coefficient and/or a partial degradation of the nonlinear grating. Optimization of the grating depth profile would permit room temperature parametric oscillation using pump wavelengths and powers attainable with diode lasers. >

Quasi-phase-matched parametric fluorescence in room-temperature lithium tantalate waveguides

We report what is to our knowledge the f irst observation of quasi-phase-matched parametric fluorescence in the 1.2-2.3-microm region, at ambient temperature, in lithium tantalate waveguides, using a pump wavelength between 805 and 845 nm. The signal fluorescent power depends strongly on the proton concentration in the waveguide, and signals of up to 7 pW have been observed for guided pump powers of 70 mW, which is 1 order of magnitude lower than the efficiency measured with lithium niobate guides.

Fabrication parameter optimization of a low-threshold high-efficiency proton-exchanged waveguide laser in Nd:LiTaO 3

Knowing the correlation between the Nd(3+) excited-state lifetime in proton-exchanged waveguides and the phase diagram of the H(x)Li(1-x)TaO(3) compound permits optimized waveguide fabrication parameters to be found. These have been used to produce a Nd:LiTaO(3) waveguide laser with a threshold of 2.9 mW and a slope efficiency of 33%, in good agreement with the best predicted values. Nevertheless this component suffers from instabilities because of the photorefractive effect.

Estimation of the extent and influence of longitudinal diffusion on LiNbO3 proton exchanged segmented stripe waveguides

Abstract A method is presented to estimate the diffusion of the protons along the propagation direction in high δ n segmented proton exchanged stripe waveguides realized on Z-cut LiNbO 3 . The result allows to explain the transmission curves observed at different wavelengths on segmented proton exchanged microguides, and can serve in designing masks for segmented guides. Loss mechanisms in the resulting structures are discussed.