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Study On The Phase Difference Of Dual Drive Mach-Zehnder Modulator In Radio-over-fiber System

Posted on:2018-02-27Degree:MasterType:Thesis
Country:ChinaCandidate:L TanFull Text:PDF
GTID:2348330515496596Subject:Circuits and Systems
Abstract/Summary:PDF Full Text Request
Radio-over-Fiber(Radio-over-Fiber,ROF)combines the flexibility of wireless communications and optical fiber transmission.It represents the future direction of communication.Optical millimeter-wave generation is one of the key technologies of Radio-over-Fiber.External modulation has advantages such as overcoming the influence of fiber dispersion,increasing the transmission distance of millimeter signal and improving the signal capacity.So it has bright prospects in application as a millimeter wave generation technology.As a typical external modulation technique,single side-band modulation hasn't affected by the periodic propagation fading,extending the transmission distance of the dispersion limit.Thus,single side-band modulation is more suitable for high-speed and long-distance transmission of millimeter-wave signal.In this paper,several generation and transmission schemes of the single side-band millimeter-wave which is based on different phase differences are studied.The results obtained are as follow:Firstly,modeling of Dual Mach-Zehnder modulator,formulae of generating millimeter wave signals which is based on the DDMZM has been derived.And then,it provides a theoretical basis for constructing ROF system with different phase difference to implement single sideband modulation.Secondly,the transmission performance of single side-band millimeter wave by using a single Mach-Zehnder modulator with two different phases modulation at 90 and 120 degrees is proposed.Among them,single side-band millimeter wave signal is generated by setting two different phase differences,and the influence of phase difference on the system performance is analyzed.The simulation results show that the power cost for two kinds of millimeter wave signal is less than 1 dB after 40 km fiber transmission while the bit error rate is at the 10-9.And the power cost of 120° phase modulation is 0.4 dB less than 90 °,the received power can be reduced by 1.25dB.On this basis,we proposed an improved single side-band modulation scheme.It has generated a new single side-band millimeter wave signals which is one side-band loading data and another side-band loading nothing by using wavelength division multiplexing.The scheme can inhibit the chromatic dispersion better.Simulation results show that the power cost of 120° is 0.35dB less than 90° with 60GHz millimeter wave signal?when the bit error rate is 10-9 and it transmits 30km after.Finally,The transmission performance of single side-band millimeter wave with three different phases modulation based on integrated Maher Del modulator is studied,which produces 90°,120° and 180°.The simulation results show that the power cost of 120° phase difference is optimal when the 60GHz millimeter wave signal is transmitted by fiber 30km and bit error rate is at 10'9.When the transmission distance of optical fiber is the same and the same error rate is adopted,180 ° has the minimum received power among then.The proposed scheme can reflect the influence of various phase differences on the transmission performance of single side-band modulation.More options are available for further study of ROF.
Keywords/Search Tags:Radio-over-Fiber system, single side-band millimeter wave, Mach-Zehnder modulator, phase difference, chromatic dispersion
PDF Full Text Request
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