Study on a radio over fibre link with improved receiver sensitivity based on polarization modulation

In this work, a radio over fibre link with improved receiver sensitivity was reported. The basical mechanism of this prototype was to realize optical single sideband modulation with an optimum optical carrier-to-sideband ratio(OCSR). To do this, both polarization modulation and optical interleaving technology were employed. The linearly polarized incident light was firstly oriented at an angle of (0 or 90) relative to one principal axis of the polarization modulator (PolM), which is biased by V and driven by RF signals. Then a polarizer with its polarization direction (0 or 90) relative to one principal axis of the PolM was used to linearize the polarization state. Finally, optical double sideband signal was converted to optical single sideband signal by using a standard optical interleaver. It is found the OCSR is only dependent on the values of two polarization angle, and . With careful adjustment, the OCSR can be reduced to 0 dB, which is the optimum value for a single RF tone modulation. The receiver sensitivity of the fibre link is analyzed by theory and then verified by simulation. It can be greatly improved by using this technique.