Passive phase correction for stable radio frequency transfer via optical fiber

The transfer of radio frequency (RF) signal via optical fiber is widely adopted in distributed antenna systems and clock standard disseminating networks. To suppress the phase variation caused by fiber length fluctuation, passive phase correction technique based on frequency mixing has been proved as a promising approach due to its significant advantages over the traditional active compensation technique in terms of complexity, compensation speed, and compensation range. The phase correction can be done either in the transmitter or in the receiver, but it usually requires many stages of electronic mixing and auxiliary microwave signals, which not only increases the cost of the link but also degrades the quality of the transmitted signal. In addition, the effect of chromatic dispersion, polarization mode dispersion, and coherent Rayleigh noise in the optical fiber will further deteriorate the phase noise of the signal after transmission. In this paper, an analytical model for the stable RF transfer system based on passive phase correction is established, and the techniques developed in the last few years in solving the problems of the method are described. Future prospects and perspectives are also discussed.