Abstract

The use of a blue laser beam in optical recording enables a fourfold increase in the information density. Such a blue beam can be obtained by the conversion of an infrared pump beam in an optical waveguide by the optically nonlinear process of second-harmonic generation (SHG). Phase matching of the guided SH and pump beams is required for efficient conversion. This requirement can usually not be fulfilled if the SH beam has to be confined in the fundamental guided mode, as is needed for obtaining a diffraction-limited blue output beam. Recently, it has been reported that, in periodically segmented domain-inverted waveguides in LiNbO₃^1,2 LiTaO₃³, and KTP,⁴ a quasitype of phase matching (QPM) can be obtained. For LiNbO₃ and LiTaO₃ two lithographic steps were needed in the fabrication of the third-order segmented waveguide structures.

© 1992 Optical Society of America