Modes in Overlayed Indiffused Optical Waveguides

The analysis of overlayed indiffused optical waveguides fabricated with ferroelectric materials (e g. LiNbO3 or LiTa03) to be employed in the realization of the hybrid integrated optic devices like modulators, switches, isolators, gyrators, optical read-out and so on is presented. In particular, the propagation constants and the mode mapping of the propagating TE and TM modes, the sensitivity of the effective refractive in dex to overlay thickness and diffusion constant, the single mode propagation criteria are derived when the substrate anisotropy is defined by a permettivity diagonal tensor. Then we have considered the effects induced by a modulating r.f. voltage that makes not null the permettivity tensor off-diagonal terms. At last, the Maxwell's equations in the diffused material region has been solved by a fast computer program based on the modified predictor-corrector method that allows a prefixed precision by varying the order and the stepsize of integration.