Electro-optic intensity modulator using higher-order resonant electrode with polarization-reversed structure

A novel structure of the electro-optic intensity modulator designed with a higher-order resonant electrode and the polarization-reversed structure is proposed. The light-modulation degradation caused by the optical transit-time effect in the electro-optic (EO) modulation area is eliminated by this scheme so that the modulation-efficiency is significantly enhanced. The modulator for 26 GHz operation was fabricated with a LiTaO₃ substrate. The modulation electrode consisted of resonant coupled-microstrip-lines and the length was set at 9.03 mm, around seven times as long as a half-wavelength, to excite the seventh order harmonic resonance by the 26 GHz RF signal. The workability of the modulator was confirmed by the experiment using 1.3 μm wavelength light.