Microwave photonic notch filter with an electro-absorption modulator in a Sagnac fiber loop

Coherence-free microwave photonic filter configurations are presented. The configurations are based on a Sagnac loop interferometer containing an electro-absorption modulator (EAM) without a nonreciprocal bias unit. Notch responses are obtained by modulating the clockwise and counterclockwise propagating waves inside the Sagnac loop at different times. Measured results verify the theoretical expressions and demonstrate a robust notch filter response extending to high frequency without reducing notch depth.