Dispersion measurement via a microwave photonic notch filter based on stimulated Brillouin scattering

In this paper, a novel method of precise dispersion measurement is proposed by exploiting the high sensitivity of the notch frequency shift and stopband rejection in microwave photonic notch filters (MPNF) based on stimulated Brillouin scattering (SBS) in optical fibers. The MPNF principle is based on an amplitude unbalance and π phaseshift between two probe wave sidebands. In case of an SBS interaction on one of the sidebands, the unbalance is eliminated. Thus, the notch filter will be formed at a specific notch frequency by the signal cancellation at the receiver. A slight dispersion mismatch leads to a notch frequency shift and a significant reduction of the notch suppression. Due to the linear dependence of the notch frequency shift on the dispersion in the vicinity of proper compensation value, even two measurements are sufficient for a precise dispersion determination.