Dual-Passband Microwave Photonic Filter Based on a Directly Modulated Microcavity Laser

An approach to achieving a highly selective and stable dual-passband microwave photonic filter (MPF) is presented. The dual-passband MPF is realized based on the phase-to-intensity modulation conversion by stimulated Brillouin scattering (SBS). The core of the proposed scheme is a two-tone pump generation by a directly modulated microcavity laser instead of two individual lasers or electro-optic modulators (EOMs), which makes the system relatively simple and stable. The center frequency of the MPF can be tuned from 0 to 20 GHz by adjusting the modulation frequency of the microcavity laser, where the center frequencies of the two passbands are related. The 3-dB bandwidth and the out-of-band rejection ratio of each passband are about 38 MHz and lager than 28.5 dB, respectively. The frequency stability of the MPF is also verified experimentally.