Second-harmonic generation efficiency in periodically poled LiNbO/sub 3/ waveguides

Quasi-phase-matched second-harmonic generation efficiency in periodically poled LiNbO/sub 3/ using titanium indiffusion, has been theoretically investigated. This permits clarifying how the involved guided modes convert the triangle-shaped form of the ferroelectric polarization in the crystal, via the overlap integral between this form and these modes, into an effective periodic nonlinear coefficient. As a consequence, the periodic function that really permits the quasi-phase-matching operation is the modulation of this effective nonlinear coefficient, the shape of which can be far from a triangular shape, as shown using different cases of mode profiles.<
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