Switchable Microwave Photonic Filter Between Dual-Notch and Dual-Passband Responses

We present a microwave photonic filter (MPF) which is switchable between dual-notch and dual-passband responses. In the MPF, a dual-drive Mach-Zehnder modulator is used to generate a quasi-single-sideband or phase-modulated signal by controlling the bias of the modulator. The first-order sidebands of the modulated signal are processed by stimulated Brillouin scattering in optical fiber to build or destroy the amplitude balance of the sidebands. In this way, a dual-notch or dual-passband MPF is finally obtained. The center frequencies of the notches or passbands are symmetric about the Brillouin frequency shift. The frequency spacing between the two notches or two passbands is determined by the frequency spacing of the dual-wavelength pump. The experimental results show that the MPF can be freely switched between dual-notch and dual-passband response with wideband tunability.