Carrier-to-noise ratio optimization by modulator bias control in radio-over-fiber links

We propose a method to optimize the carrier-to-noise ratio (CNR) in optically amplified narrowband radio-over-fiber links which employ a Mach-Zehnder modulator. This is achieved by control of the modulator bias in order to suppress the optical carrier. In this letter, we experimentally prove that this carrier suppression technique can simultaneously improve the link detected RF power and suppress the stimulated Brillouin scattering, which is shown to be an important source of noise. Thus, we observe an improvement of about 20 dB in CNR of our link with respect to the unsuppressed carrier case