Full-duplex radio-over-fiber system based on a modified single-side band modulation

A full-duplex radio-over-fiber system based on a modified single-sideband using external modulator is proposed and demonstrated At the central station a CW lightwave is intensity-modulated by a RF signal to generate a DSB signal After the central carrier and the two first-order sidebands are separated by a FBG the central carrier is modulated with a baseband data at 25 Gbit/s Then it is recombined with the unmodulated first order sidebands to generate optical millimeter-wave by an optical coupler with a certain coupling coefficient and transmitted to the base station over single-mode fiber The central carrier and one of the first-order sidebands are beaten to generate the mm wave when they are detected by an optical receiver Another first sideband is reused as carrier for uplink connection The dispersion performance of the generated mm-wave is theoretically analyzed one can see that the effect of dispersion and requirement of the optical power are reduced The PIN PD can avoid working in a high-DC saturation range which may distort the RF components and depress the responsibility of the detector The stimulant results show that the system can reduce the effect of dispersion effectively and Immune the fading effect and the walking-off signals It is suitable for a long distance transmission (C) 2010 Elsevier BV All rights reserved