Guided-Wave Electro-Optic Modulators Using Novel Electrode Structure of Coupled Microstrip Line Resonator

摘要

A novel structure of guided-wave electro-optic modulators is proposed and their operation of the optical intensity modulation is successfully confirmed. The modulators use a newly developed modulation electrode consisting of coupled microstrip lines. A high voltage can be induced by the resonance of the odd propagation mode to realize efficient electro-optic modulation in spite of the microstrip-line configuration. The properties of the coupled microstrip lines were analytically evaluated by using the method of conformal transformations and the effectiveness as a modulation electrode was presented. The modulation electrodes of the half-wavelength coupled microstrip line resonator were designed at 10 GHz and 26 GHz, where the electrode lengths were 3 mm and 1.2 mm, respectively. The modulators using these electrodes with the Mach-Zehnder interferometer of LiTaO_3 waveguides were fabricated. The measured modulation coefficient of the 26 GHz modulator normalized at 100 mW signal input was 0.13 rad.