Stimulated Brillouin scattering tunable fiber based all-optical filter

In this paper we present a novel configuration for an all-fiber tunable infinite impulse response (IIR) optical filter using stimulated Brillouin scattering. By applying the Brillouin acoustic waves within the coupling area of an optical coupler, we can control its transmittivity and so to affect the spectral response of the IIR optical filter. In this paper we explain the principle of operation of the proposed device and experimentally demonstrate the ability to control the spectral response of an optical filter based on fiber ring resonator configuration. We presented preliminary experimental results which demonstrate the potential of the proposed method for the realization of a tunable optical filter, by achieving a change of about 0.7 dB in the depth of the spectral response of the filter. Such device could be used for realization of many all-fiber optical components such as modulators and switches. In future work, an improvement of the filter may be realized, by using the short loop configuration, and a narrower laser source for the input signal.