**3.4 Dispersion compensation in RoF systems**

Compensating dispersion penalty is a key problem when next generation Radio-over-Fiber networks are built. Several techniques have been proposed to overcome dispersion effect. An alternative method is presented to overcome the RF carrier suppression effect in optical links based on the joint effect of SOA chirp, chromatic dispersion and nonlinearities of the optical fiber. The results show that the frequency notches caused by the dispersion-induced carrier suppression effect may be sharply alleviated and the performance of the transmitted digital signal can be improved.

The SOA dispersion compensator has the advantage that it is a loss-less, wide band solution with robust operation. It is more efficient than midway optical phase conjugation or self phase modulation effect introduced by the fiber. It offers optical amplification compared with high insertion loss of dispersion compensation fiber. It has high bandwidth (30-35nm), hence it is transparent for optical or electrical carrier variation and more insensitive for environmental and system parameters than Fiber Bragg Grating. It is semiconductor based device, which can be easily integrated with semiconductor optical source. So it doesn't demand expensive and complex optical device (like SSB Mach-Zehnder modulator), just an additional integrated section is necessary in the optical source. Additionally the operation of the device can easily be optimized by bias point and input optical power control.
