Hybrid OFDM and Radio-Over-Fiber Transport System Based on a Polarization Modulator

A hybrid orthogonal frequency-division multiplexing (OFDM) and quadruple-frequency radio-over-fiber (RoF) transport system is developed based on colorless optical polarization beam splitters and an optical polarization-arrangement technique. No optical filter is required to eliminate any specific optical wavelength from the hybrid transport system; the employed optical wavelength and central carrier frequency of the transmitted radio-frequency signal can be dynamically adjusted without alerting the transmission performance of the proposed hybrid transport system. To prove the concept of the quadruple-frequency technique, a 40-GHz millimeter-wave (MMW) signal quadrupled from a 10-GHz signal is experimentally demonstrated in an optical domain. Its advancement is then employed to experimentally accomplish a hybrid OFDM and quadruple-frequency RoF signal transmission over a 25-km span of single-mode fiber. The advancement of the hybrid transport system is evaluated and demonstrated by error-free transmissions and clear eye and constellation diagrams. This proposed system is a great candidate for greatly reducing the cost of simultaneously transmitting OFDM and MMW signals over optical access networks and makes it more practical to be employed.