Observation of an all-fiber Fano resonance comb.

This study demonstrates the generation of a tunable all-fiber Fano resonance comb by incorporating a 10° tilted fiber Bragg grating (TFBG) into an all-fiber Mach-Zehnder interferometer (MZI). The TFBG generates the discrete state that couples with the continuum state of the MZI to produce all-fiber Fano resonance comb spanning an 80 nm spectral range. This system exhibits precise tunability, enabling continuous transitions among asymmetric Fano line shape, symmetric electromagnetically induced transparency, and electromagnetically induced absorption line shapes. The results also demonstrate that key spectral parameters, including the Fano parameter q, slope rate, and extinction ratio, exhibit periodic variation. The proposed approach offers a robust, low-loss, and scalable solution for multi-Fano resonance generation and holds promise for applications of high-sensitivity sensing and optical switching.