Coherence-free microwave photonic notch filter with a single driver intensity modulator in a Sagnac fiber loop

A coherence-free microwave photonic filter configuration is presented. The configuration is based on a Sagnac loop interferometer containing a single-drive intensity modulator without a nonreciprocal bias unit. A notch response is obtained by modulating the clockwise and counterclockwise propagating waves inside the Sagnac loop at different times. A general theoretical analysis for both the reflected signal and the transmitted signal is obtained. Measured results verify the theoretical expressions and demonstrate a robust notch filter response.