Abstract

Potassium titanyl phosphate (KTiOPO₄, KTP) is a very promising material for the development of a compact blue light source based on frequency doubling because of its large nonlinear coefficient and high optical- damage threshold. For generation of wavelengths shorter than 497 nm, type-II biréfringent phase matching cannot be used¹ and quasi-phase matching must be used instead, Quasi phase matching can be achieved by periodically reversing the sign of the d₃₃ nonlinear coefficient, and this can be accomplished through periodic inversion of the ferroelectric domains of the material. Previously, an ion-exchange technique has been used to produce segmented waveguides having periodic domain inversion.²,³ However, this technique has several draw'- backs: (i) the domain-inverted region may not be as deep as the waveguide, (ii) the reliability and reproducibility of the ion-exchange process are questionable, and (iii) the processing parameters that give good domain inversion may not yield an optimized waveguide. Hence, an alternative technique that overcomes these difficulties is desirable. Here we report what we believe to be the first QPM waveguide device fabricated in KTP by using an electric-field-poling technique that produces deep domains⁴ and permits independent optimization of the linear and nonlinear properties of the device.

© 1995 Optical Society of America