Low cost high capacity data transmission over plastic optical fibre using quadrature amplitude modulation

While a data transmission system based on step-index multi-mode plastic optical fibre (POF) is potentially of very low cost, it is also severely bandwidth-limited. To circumvent the bandwidth limitation, Quadrature Amplitude Modulation (QAM) may be used to realize high capacity data transmission. Three different QAM systems with large-core step-index plastic optical fibre are proposed. They are Direct QAM, Baseband/subcarrier emulated QAM, and Wavelength-sliced emulated QAM. The performances of the three systems have been analyzed by computer simulations. Based on the simulation results, the technical feasibility for those system concepts is assessed in order to select the optimal configuration. A simple Direct QAM system has been set up. Measurements have been carried out with different optical sources; a 658 nm laser diode and a 520 nm SLED. A vector signal generator is employed as QAM modulator and the quality of the I and Q signals was measured by a vector signal analyzer. 90 Mbit/s over 100 meter step-index plastic optical fibre with a core diameter of 1 mm has been achieved with an error vector magnitude less than 3%