Optical up-conversion of single sideband signal using frequency quadrupling technique for radio over fiber system

This paper proposes a novel method for optical up-converted single-sideband (SSB) signal generation in radio over fiber link, capable of high tolerance of fiber chromatic dispersion induced carrier fading effect. The OSSB signal, is generated by utilizing one low-bandwidth intensity modulator (IM) under frequency quadrupling modulation scheme with low-frequency local oscillator (LO) signal and one low-bandwidth IM biased at the null point in combination with fiber grating. With this up-converted SSB technique, a 26 GHz optical SSB radio frequency (RF) signal is generated by mixing a low frequency local oscillator (LO) signal (5.5GHz) and an intermediate frequency (IF) signal (4 GHz) carrying 80 Mbps quadrature phase shift keying (QPSK) vector signal. The signal is transmitted over 45 km standard single-mode fiber (SMF) successfully and shows negligible dispersion-induced carrier suppression effect. The received signal error vector magnitude (EVM) is 13% rms and 15.7 % rms before and after transmission over 45-km SMF.