Abstract

The performance of multi-band (MB) orthogonal division frequency multiplexing (OFDM) ultra-wideband (UWB) over fiber transmission using a low cost electro-absorption modulator integrated laser (EML) is investigated in details. Various parameters such as fiber length, bias voltage, bias current and temperature of the EML are systematically evaluated to illustrate the effects on the performance of this Radio over Fiber (RoF) system. It is found that for the considered EML, the optimum normalized input (modulation) power is {598}0.068 at bias voltage of 0.26 V. When modulation voltage is low the performance is mainly limited by signal to noise ratio, but mainly limited by EML response nonlinearities when modulation power is high. Theoretical analysis of the effect of fiber dispersion and EML response nonlinearities on system performance is carried out considering amplitude and phase distortion. Experiments are conducted and verified by our theoretical analysis, and good agreement between the experiments is obtained. The effect of fiber chromatic dispersion induced laser phase to intensity noise conversion or relative intensity noise (RIN) on performance is investigated in terms of laser intrinsic RIN, laser linewidth, fiber dispersion and carrier frequency. The effect of nonlinearities of the EML on the OFDM subcarriers for MB-OFDM UWB over fiber system is investigated in terms of the intermodulation distortion (IMD) products. In addition, adjacent channel power ratio (ACPR) is also analyzed and calculated in order to abide with ECMA standard and have less interference to coexisting channels.