Research On Millimeter-wave Photonic Generator And Radio Over Fiber System

With the increasing demand for data,broadband communication gradually develops towards a higher frequency band.However,high frequency microwave/millimeter wave will be interfered by strong atmospheric attenuation and diffraction difference in wireless communication.In addition,due to the electronic bottleneck,it is difficult to generate microwave signals exceeding 60 GHz using traditional electronic methods.Microwave photonic solutions can be employed to generate high-quality millimeter waves.Photon-assisted millimeter wave is an important research direction in microwave photonics,One important feature of millimeter waves is their capability to be easily integrated and transmitted with optical fiber.With the mature technology that is available,the effective range of millimeter wave propagation can be dramatically increased and therefore,enable transmitting large amount of data through optical fiber.It can be compatible with radio over fiber system and provide a better service for broadband wireless access.ROF system combines the merits of optical fiber communication and wireless communication,which can really solve the coverage problem of high frequency signals.In addition,the bidirectional ROF system can realize wavelength reuse in base station to reduce the complexity.Based on the current research status of optically generated millimeter waves,in this paper,the high frequency MMW generator scheme is studied,and the transmission performance of ROF system based on high frequency MMW generator is studied.In addition,a ROF system with tunable frequency factor is proposed and verified.The main contents of this paper are as follows:(1)In this paper,a 36-tuple millimeter-wave generator scheme is proposed.dual-Parallel Mach-Zehnder Modulators(DPMZM)is used to obtain ±6 order optical sidebands signals.Then ±18 order optical sidebands signals are obtained based on the four-wave mixing(FWM)effect of SOA.Finally,36-tuple frequency signals were generated after filtering and beating.The OPTISYSTEM platform is used to verify this scheme.The results show that the system can obtain pure millimeter-wave signals relatively,and the effects of non-ideal factor(modulator extinction ratio and phase shifter migration)on optical sideband suppression ratio(OSSR)and radio frequency spurious suppression ratio(RFSSR)is analyzed.The frequency tunability of the system is verified and obtain millimeter wave signals from 144 GHz to 252 GHz.In addition,a ROF system based on 36-tuple millimeter wave is proposed,180 GHz MMW signal is generated from a 5GHz microwave-driven signal.Two modulation formats are used to analyze the performance of the system,and the impacts of SOA’s injection current on sideband ratio(SR)and bit error rate(BER)are studied.(2)In order to make full use of the band resources,a radio-over-fiber system with tunable frequency multiplication factor using a Mach-Zehnder modulator is proposed.The system realizes that the signal output of different frequencies by using MZM combined with wavelength selective switch module.Combined with coherent detection,wavelength reuse,digital signal processing,the frequency multiplication factors in the upper and lower links of ROF system is optional.This scheme greatly reduces the construction cost of the base station because where is without additional lasers.The system’s frequency multiplication factor can be set one of 1,3,5,6 of downlink,and its transmission minimum error vector magnitude is5.5%～7%;the system’s frequency multiplication factor of uplink can be selected from 0～12,and its transmission minimum error vector magnitude is 6.4%～8.6%.