Millimeter-wave band optical single-sideband modulator using array-antenna-electrode and polarization-reversed structures with asymmetric Mach–Zehnder waveguide

The radio-over-fiber (RoF) technology is effective in millimeter-wave (MMW) wireless systems for future broadband massive mobile communication. In constructing MMW RoF systems, a device for converting MMW signals into lightwave signals is important. In particular, a conversion device for optical single-sideband (SSB) modulation is rather attractive since the signal fading caused by the chromatic dispersion effect of an optical fiber does not occur. We have proposed a new optical SSB modulator using array-antenna-electrode and polarization-reversed structures with an asymmetric Mach–Zehnder waveguide for MMW band RoF systems. By introducing polarization-reversed structures in electro-optic modulators, it is possible to control the optical modulation phase arbitrarily. Therefore, by combining with an asymmetric Mach–Zehnder waveguide, we can obtain the SSB optical modulation in the MMW band without an external power supply. In the experiment, SSB modulation characteristics and the switching of enhanced sidebands were successfully demonstrated in the 60 GHz band.