Frequency quadrupled/ twelve-tupled millimeter-wave ROF system without bit walk-off effect by a dual parallel polarization modulator

• Adopting the same structure, we can simultaneously generate a quadrupled/twelve-tuple millimeter wave ROF system without filters. Those systems can overcome the fiber dispersion and greatly increase the fiber transmission distance. • Our proposed scheme can solve the problem of DC bias drift and the limited extinction ratio caused by MZM. The general method to generate the optical millimeter wave is using MZM. A novel frequency quadrupled/ twelve-tupled millimeter wave(MMW) radio over fiber (ROF) system without the bit walk-off effect based on a dual parallel polarization modulator (DP-PoIM) is proposed. At the central station, adopting a composite radio frequency (RF) driving signal as the RF driving signal to the DP-PoIM, the data signal is modulated only on + 2th/+6th order optical sidebands. The composite signal is formed by combining two signals, one is formed by the data being modulated by the RF driving signal with a phase modulator, and the other is formed by the data being amplified by an electrical amplifier. At the base station, part of the −2th/-6th order sideband is reflected out firstly by a fiber Bragg grating(FBG) and used as the optical carrier for the uplink, and then the signal through the FBG is injected into a photodetector to generate frequency quadrupled/ twelve-tupled MMW with the downlink data. The innovation of this paper is to modulate the downlink data signals only on the + 2th/+6th order optical sidebands by DP-PoIM. Our proposed system not only can overcome the effect of bit walk-off, but also solve the problem of DC bias drift of the Mach-Zehnder Modulator.