Waveguides in Ti:LiNbO3 for second harmonic generation: Design and experimental tests

Second harmonic (SH) generation in optical waveguides is widely studied for its many applications. In order to obtain efficient non-linear phenomena in waveguides, it is ver). important that the optico-physical characteristics of the fabricated waveguides are exactly those foreseen in the project. This because in practical applications operation wavelength and temperature can rarely be adjusted to achieve phase-matching conditions. The present work describes a model that, once fixed the operation conditions, finds the optico-physical characteristics of Ti:LiNbO3 planar waveguides necessary to obtain SH generation and relates them to the fabrication parameters. Phase-matching conditions between the two interacting guided modes (fundamental and SH) are achieved by exploiting the material birefringence. The investigation is performed at a fundamental wavelength of 1.064 mu m and at room temperature on Y-cut, X-propagation waveguides. The waveguides, fabricated according to our design, were then characterised at different wavelengths. Experimental tests of SH generation confirmed the goodness of the model proposed.