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 depen dence of the velocity match condition on electrode thickness and wall angle is demonstrated experimentally and with finite element calculati ons. A set of test electrode structures is fabricated to study electri cal losses in the modulator electrode. Loss coefficients are assigned to different sections of the device, and dielectric and radiative loss es are shown to play an important role at high frequencies. This infor mation is used to conjunction with finite-element calculations to deve lop accurate models for both the electrical and optical responses. The frequency dependence of the half-wave voltage is measured and shown t o be in good agreement with a model.