Research On Millimeter Wave Technology On Dual Wavelength Laser And Its Performance Analysis

With the development of communication technology,the demand of users for mobility and broadband of communication is increasing.As an emerging broadband access technology,Radio-Over-Fiber(ROF)meets the requirements of large capacity and mobility of communication systems.As the local oscillator and the emission source of the ROF system,good performance of Millimeter-wave and millimeter-wave generation system is essential for ROF system.The current generation of millimeter-wave schemes is mainly photonics.The photonics method has a great advantage compared with the electronic method with large phase noise,but which also has shortcomings.On the basis of the secondary heterodyne,a millimeter-wave scheme based on dual wavelength laser is proposed in this paper,and the parameters affecting the scheme are analyzed and simulated including system phase noise,laser linewidth and fiber dispersion.The research work in this paper is mainly reflected in the following aspects:(1)Firstly,the background and significance of the research are introduced.ROF technology including ROF system principle,structure classification and system technology advantages are mainly introduced,and the application status of ROF technology is analyzed.(2)The advantages of millimeter wave and millimeter wave communication are introduced,including millimeter wave propagation mode and millimeter wave communication.The principle and system structure of the existing photonics millimeter-wave generation technologies are analyzed,including direct intensity modulation,external modulation,up-conversion and optical heterodyne.The advantages and disadvantages of various techniques are analyzed too.(3)On the basis of the secondary heterodyne,a new scheme of generating millimeter wave based on dual wavelength is proposed.The structural principle and mathematical model of the optical devices used in the scheme are analyzed,including the Mach-Zehnder modulator,dual parallel Mach-Zehnder modulator,photo-detector and fiber Bragg grating.The system schematic is given theoretically and the frequency of millimeter wave is eight times as much as the local oscillator signal which is got by the formula theory.The system is simulated by OptiSystem optical simulation software,which has obtained the millimeter wave of 60GHz5 verifying the feasibility of the scheme by simulation analysis.(4)The factors affecting the system performance are discussed,including system phase noise,fiber dispersion and laser line width.By the theoretical analysis,the mathematical model of the relationship between millimeter wave power cost and fiber length,millimeter wave power cost and laser linewidth is obtained.The simulation results show that the power cost of millimeter wave increases with the increase of fiber dispersion and the increase of laser linewidth.The eye diagram and bit error rate of the system under different laser linewidth conditions are obtained by OptiSystem simulation,which furtherly illustrates the effect of laser linewidth on system performance.The millimeter-wave signal generated by this scheme is not influenced by phase noise in ideal condition proved by mathematical model established by theoretical analysis.And the original baseband signal is demodulated at 60GHz by OptiSysteml 0.0,which proves that the generated The performance of the 60 GHz millimeter-wave is not affected by the phase noise.(5)The advantage and disadvantage of the millimeter-wave scheme based on the second-order heterodyne method are summarized and analyzed,and suggestions for the future work are given.