We achieve Fano-like resonances in an all-in-fiber structure embedded with an in-line Mach-Zehnder interferometer (MZI). A fiber Bragg grating is inserted into MZI's one arm to form a resonance, which functions as the discrete state of the Fano-like resonance to couple with the continuum propagating mode of MZI in the fiber core. A theoretical model predicts the controllable resonance lineshape by changing the phase difference between the MZI's two interference pathways. Fano-like resonances with an extinction ratio over 20 dB are experimentally observed, which are reliably tuned into Lorentzian and electromagnetically induced transparency-like resonances by versatile methods. The realization of Fano-like resonances with broad tunability in this all-in-fiber structure holds potentials in fiber-based applications of sensing, signal processing and nonlinear optics.
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Funding: National Natural Science Foundation of China (Grant Nos. 61775182, 61505165, and
61522507), the Natural Science Basic Research Plan in Shaanxi Province of China (Grant No. 2019JM-330), the
Fundamental Research Funds for the Central Universities (Grant No. 3102019PB005), the Key Laboratory of
Opto-electronic Information Technology, Ministry of Education (Tianjin University) (Grant No. 2019KFKT007), and the Marie
Skłodowska-Curie Individual Fellowships in the European Union’s Horizon 2020 Research and Innovation Programme
(Grant No. 660648).
- Fano-like resonance
- fiber Bragg grating (FBG)
- Mach-Zehnder interferometer (MZI)