A novel scheme for orthogonal frequency division multiplexing-radio over fiber based on modulator and dithering technique: Impact of self phase modulation and group velocity dispersion

Abstract

Nonlinearity characteristic in OFDM (Orthogonal Frequency Division Multiplexing)-RoF (Radio over Fiber) system which causes the frequency shift of light and has a high electrical field on medium transmission. We begin by discussing SPM (Self Phase Modulation) and GVD (Group Velocity Dispersion) are part of nonlinear characteristic. SPM induced spectral broadening will be degrade performance of light wave and GVD will be impact on duration pulse of optic. The impaired information signal reduces the power and later affects the quality of signal. This research aims to focus on the improvement of two external modulator LiNbO3 MZM (Lithium Niobate-Mach Zehnder Modulator) and applying of frequency dithering techniques to reduce the existing nonlinearity of the optical fiber purposely to enhance the receiving power for the lower input power with the length of fiber up to 100 km. Finally, the result shows an average of 18.5% increase in the power level for linewidth of 1 MHz, 3 MHz, and 7 MHz across 50 km distance with the log BER (Bit Error Rate) -2.407, BER 0.003, and SNR (Signal to Noise Ratio) 43.8, across 100 km of optical fiber the value of log BER -2.471, BER 0.003, and SNR 49.14.