The Study Of Millimeter-wave Orbital Angular Momentum Communication Base On Radio-over-fiber Technology

With the rise of the new strategic industry such as Internet+ and Internet of Things,as well as the growth demand of personal communication business,the contradiction between limited spectrum resources and growing communication demand has become increasingly prominent.The existing communication systems that use traditional physical dimensions such as wavelengths,amplitudes,phases,and polarizations to modulate information have been difficult to meet the demand,and there is an urgent need to find a new communication technology or physical dimension to meet current communication development needs.In this context,the electromagnetic vortex carrying orbital angular momentum(OAM)has become one of the hot topics in the academic field.OAM?which has infinite state,is a new dimension which is different from the traditional physical dimension.And the electromagnetic vortices with different OAM state are orthogonal to each other.Based on this,it is possible to improve the capacity and spectrum efficiency of the communication system by using the OAM as a multiplexing method or modulation method.Based on the analysis of electromagnetic vortex theory,this paper studies the reliability and feasibility of information transmission of OAM communication system by combining ROF technology,CAAs technology and DDO-OFDM.And the characteristics of electromagnetic vortex generation and detection based on ROF technology and the performance of converged communication system are studied.The work mainly includes the following aspects:1.Aiming at the problem of low efficiency and high complexity of traditional electromagnetic vortex generation method,a method of generating electromagnetic vortex based on ROF technology is proposed.In this method,we employ ROF technology in the optical domain to generate W-band optical millimeter wave(mm-wave)by frequency multiplication,and we regulate phase and amplitude of optical mm-wave in the integrated optical modulator.By adjusting the phase shift of mm-wave radiated by CAAs,we can achieve the generation and state switching of mm-wave vortex.And the influence of the transmission distance and the radius of the CAAs on the generation of the mm-wave electromagnetic vortex is explored.2.Based on the analysis of the commonly used detection method of OAM,the detection and demodulation method of the electromagnetic vortex based on the CAAs is proposed.3.We proposed a mm-wave OAM converged communication system based on ROF technology.Meanwhile,we also design the 64-order three-dimensional modulation format consist of OAM,phase and amplitude.Through simulation,the modulation/demodulation of 75Gbps combined modulation signal in the BTB(Back to back)and 20km SMF(Single mode fiber)transmission is realized successfully.4.In order to further enhance the spectrum utilization rate,we integrate DDO-OFDM technology into the mm-wave OAM converged communication system,and the modulation/demodulation of the combined modulation signal in BTB is realized.Through the work mentioned above,it is shown that the mm-wave OAM converged communication system based on the above methods and techniques is feasible in engineering,and can be realized in technology.