A wavelength division multiplexing radio-over-fiber system with 58 GHz optical orthogonal frequency division multiplexing millimeter-wave signal

A wavelength division multiplexing radio-over-fiber (WDM-ROF) system to generate 58 GHz optical millimeter (mm)-wave with OFDM signal by using a Mach-Zehnder intensity modulator and an optical interleaver (IL) is experimentally investigated. In the central office, four channels continuous lightwaves are generated by a laser array, and they are modulated by a intensity modulator which is driven by a 29 GHz radio frequency (RF) signal to realize double sideband (DSB) modulation. 2.5 Gb/s OFDM signals are modulated on the DSB signals by another intensity modulator before they are transmitted to the base station over 20 km single mode fiber (SMF). In the base station, an optical IL is used to separated optical carriers and first order sidebands. The first sidebands of desired channel are selected by a tunable optical filter (TOF) and detected by a high speed optoelectronic detector to generate 58 GHz electrical mm-wave which is demodulated by coherent demodulation to retrieve downstream OFDM baseband signals. The experimental results show that the power penalty of the downstream OFDM signals transmitted over 20 km SMF-28 is less than 0.5 dB at the BER of 10^-3 and without dispersion compensation, and the constellation figures are still clear.