Experimental Demonstration of Mixed-Polarization to Linearize Electro-Absorption Modulators in Radio-Over-Fiber Links

We experimentally investigate optical mixed polarization for the linearization of an electro-absorption modulator (EAM) in radio-over-fiber links. A linear polarizer is used before and after a polarization-dependent EAM. Thus, both transverse-electric and transverse-magnetic polarized lights are simultaneously modulated by different amounts. By carefully optimizing two polarization angles, the third-order intermodulation distortion (IMD3) is suppressed. The linearization leads to suppression of the IMD3 by more than 16 dB and improvement of spurious-free dynamic range by 8.1 and 9.5 dB for back-to-back and after 20 km of fiber transmission, respectively, compared to the nonlinearization case.