Array-antenna-electrode electro-optic modulators for millimeter-wave radio-over-fiber systems

We have proposed and developed array-antenna-electrode electro-optic (EO) LiNbO 3 modulators to convert wireless millimeter-wave signals to optical signals. In particular, by introducing polarization-reversed structures in the LiNbO 3 crystal/film of the device substrate, the advanced functions of discrimination between space-division-multiplexed (SDM) wireless signals and generation of optical single-sideband (SSB) modulation signals are obtainable. In this paper, newly developed EO modulators operating in the 60 GHz band are presented. Applications to up-links in fifth generation (5G) mobile communication systems are also discussed.