The Research Of The Technology Of Photonic Generation Of Millimeter Wave Signal In ROF

The technology of Radio over Fiber(ROF)is a physical layer technology that combines the advantage of optical fiber communication technology with the advantage of wireless communication technology.It uses optical fiber to transmit signal and has the advantages of low transmission loss,large transmission bandwidth,immunity to electromagnetic interference,etc.In the meantime,it also possesses the advantages of flexibility and mobility due to including the wireless communication,and provides a solution to the problem of narrow band width and short transmission distance in the next generation ultr-wideband wireless access network.Many technical factors play an important role in the quality of optical wireless communication system Communication,inside,high-quality millimeter-wave technology plays a key role in the communication quality of the whole communication system.In this paper,the principles and applications of ROF system and photonic generation of millimeter-wave signal are discussed,and theoretical analysis and VPI simulation for realizing several intensity modulation types using dual-drive Mach-Zehnder modulator are carried out.Meanwhile,this paper proposes two schemes for generating frequency-octupling millimeter-wave signal based on two cascade dual-drive Mach-Zehnder modulator.The first scheme uses two dual-driveMach-Zehnder modulators and a bandstop filter to produce a frequency-octupling millimeter-wave signal,and theoretical analysis and VPI simulation is achieved,in addition,the effect of extinction ratio in 100 dB and 35 dB on optical harmonic suppression ratio and electric harmonic suppression ratio is analyzed.The second scheme is improved on this basis,using four parallel and cascaded dual-drive Mach-Zehnder modulators to produce a frequency-octupling millimeter-wave signal.Compared with the first approach,the system employing two cascade dual-drive Mach-zendell modulators instead of the bandstop filter,and the optical carrier can be suppressed by adjusting the dc voltages on the two cascaded Mach-Zehnder modulators,in the meantime,optical sideband suppression ratio is improved.When the extinction ratio is 100 dB,the optical harmonic suppression ratio can reach 50 dB and the electric harmonic suppression ratio can reach 43 dB.At the end of the paper,the phase difference offset and dc bias voltage difference offset are analyzed.When the phase difference between MZM-1 and MZM2 is set as ?/2,and the dc bias voltage difference between MZM-3 and MZM-4 is set as 16.6V,the best photonic harmonic suppression ratio is reached.