Characterization and simulation of proton-exchanged integrated optical modulators with various dielectric buffer layers

Abstract

Fast and accurate numerical techniques are developed for calculating the optical depth of modulation of integrated-optical devices with various dielectric buffer layers. The matrix effective refractive-index (MERI) method is used in calculating the LiNbO3 proton-exchange single-channel optical-mode parameters. An approximate technique for calculating electrode electric field distributions as a function of various buffer layers is presented. Comparisons of computer simulations to experimental measurements performed on Mach-Zehnder modulators containing various buffer layers demonstrate that the numerical techniques are sufficiently accurate for usein computer-aided design. The errors between calculated and measured V(pi) are given for modulators with a 200 nm SiOî buffer layer and with a 200 nm ITO electrode structure. In general, given the same electrode dimensions, the use of ITO electrodes results in a significant reduction of the drive voltage required as compared to electrodes on thin (200 nm) dielectric buffer layers.