| Radio over fiber(Ro F) combines the mobile communication and fiber communication, which features very high bandwidth, low transmission loss and being immune to electromagnetic interference, compared with the traditional RF communication system, and has attracted great interest in recent years.However, due the nonlinearity of the optical modulator and the dispersion of the fiber, the microwave signals distributed in the Ro F system will be distorted, so it is very important to study high performance Ro F link. The content of the thesis can be summarized as below:First, the key features of the Ro F link is presented; second, the principle of some important devices and components, such laser diode, optical modulator, optical fiber, and photodetector, employed in a Ro F link is briefly introduced; finally, two Ro F links with improved dynamic range and dispersion performance are proposed and experimentally studied.An optimized linear Ro F link is lucubrated based on a fiber Bragg grating(FBG) and a length of SMF. The experiment results show improve in the linearity of the system and the adaptability to the ferequency and band.A high-performanced Ro F link based on a DEMZM is reaserched. We utilize the chirp of the DEMZM to overcome the peridic fading. The linearity can also be improved by introducing different phase shifts to different optical sidebands and appropriate DC bias. We lucubrate the theory and the experiment results show that, by changing the bias voltage of the DEMZM, the power fading can be suppressed at any frequency and the SFDR is increased by 14.9 d B compared with the case with power fading. For the compensation of the nonlinearity, the SFDR is improved by 14.4 d B And the gain is improved by 4.5d B. We also lucubrate and experimental confirmate the adaptability of the system to the ferequency and band, the experiment results indicate that the IMD3 can be restrained by 20 d B at least when the changing the ferequency in the range of 2 GHz or enlarging the band to 1GHz. |
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