FSK signal generation with wavelength reuse capability in 8 Gbit/s radio over fiber systems

In this paper, a technique was numerically implemented to generate a frequency shift keying (FSK) radio-over-fiber (RoF) signal in optical domain. Due to the oscillator free generation of FSK signal, this scheme is highly stable with reduced complexity and extremely cost effective. The remote heterodyne detection method was used to detect the signal, where beating occurs to detect the FSK signal. With this scheme, it is able to efficiently generate FSK signal in the range of 60 and 75 GHz at 8 Gbit/s and effectively transmit it over 80 km link without degrading the signal shape and quality. The nonlinear threshold (NLT) point of the system has also been numerically analyzed to estimate the nonlinear tolerance of the system. Besides, the impact of transmission distance and polarization mode dispersion (PMD) was evaluated. Furthermore, the wavelength reuse for the uplink was implemented in the scheme by reusing the same wavelength for uplink that was used for signal generation at downlink. The whole process was performed in optical domain. Thus this scheme is very cost effective as the overall architecture of RoF system is simplified.