Effect of Nonlinear Phase Variation in Optical MillimetreWave Radio over Fibre Systems

In this paper, we propose an optical millimetre wave radio-over-fibre(mm-wave RoF) system that uses a dual drive Mach Zehnder modulator(DD-MZM), which is biased at the maximum transmission biasing point,to generate an optical double sideband-suppressed carrier. The input tothe DD-MZM are binary phase shift keying (BPSK), quadrature phase shiftkeying (QPSK), 8-phase shift keying (8-PSK) and 16-qaudratureamplitude modulation (16-QAM) schemes at a carrier frequency of 5 GHzwith a rate of 2 Gsym/s and a local oscillator of 15 GHz obtain an mmwaveRoF signal at 30 GHz. We evaluate the generation and performancesof the proposed system in terms of the power penalty, the error vectormagnitude and the bit error rate (BER). Impairments including the selfphasemodulation, chromatic dispersion and attenuation are consideredwhen modelling the single mode fibre (SMF) based on the symmetricalsplit step Fourier method. We show that the power efficiency improves inthe optimum region on average by ~11 dB, ~11 dB, ~12 dB and ~18 dBfor BPSK, QPSK, 8-PSK and 16-QAM, respectively for the same opticallaunch power over 10, 30 and 50 km of SMF compared to the linear andnon-linear regions.