PERFORMANCE AND MODELING OF BROAD-BAND LIBNBO3 TRAVELING-WAVE OPTICAL-INTENSITY MODULATORS

The design, fabrication, and characterization of a travelling wave Ti:LiNbO3 Mach-Zehnder interferometric modulator are discussed. The dependence of the velocity match condition on electrode thickness and wall angle is demonstrated experimentally and with finite element calculations. A set of test electrode structures is fabricated to study electrical losses in the modulator electrode. Loss coefficients are assigned to different sections of the device, and dielectric and radiative losses are shown to play an important role at high frequencies. This information is used to conjunction with finite-element calculations to develop accurate models for both the electrical and optical responses. The frequency dependence of the half-wave voltage is measured and shown to be in good agreement with a model.