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Journal Article
Critically coupled Fabry–Perot cavity with high signal contrast for refractive index sensing
- Authors
- Gyeong Cheol Park, Kwangwook Park
- Issue Date
- 2021-10
- Citation
- Scientific Reports, v.11, pp.1-10
- ISSN
- 2045-2322
- Publisher
- Nature Research
- Language
- English
- Type
- Journal Article
- Abstract
- Perfect absorption at a resonance wavelength and extremely low absorption at the wavelength range of off-resonance in a one-port optical cavity is required for refractive index (RI) sensing with high signal contrast. Here, we propose and analyze an absorption-enhanced Fabry?밣erot (MAFP) cavity based on a critical coupling condition in a near-infrared wavelength range. For a one-port cavity, a thick bottom Au is used as a mirror and an absorber. To achieve the critical coupling condition, a top dielectric metasurface is employed and tailored to balance the radiation coupling and the absorption coupling rates, and the one-port cavity is theoretically analyzed using temporal coupled-mode theory. We investigate two types of MAFP structures for gas and liquid. The gas MAFP cavity shows a sensitivity of ~ 1388혻nm/RIU and a full-width at half-maximum of less than 0.7혻nm. This MAFP cavity resolves the RI change of 5 × 10?닋4 with a reflectance signal margin of 50% and achieves a signal contrast of ~ 100%. The liquid MAFP cavity shows a sensitivity of ~ 996혻nm/RIU when RI of liquid changes from 1.30 to 1.38. With tailoring the period of the metasurface maintaining its thickness, a signal contrast of ~ 100% is achieved for each specific RI range.
- KSP Keywords
- Full width at half maximum(FWHM), High signal, Near-infrared, Off-resonance, Optical cavity, Refractive index sensing, Resonance wavelength, Wavelength range, critical coupling, dielectric metasurface, infrared wavelength
This work is distributed under the term of Creative Commons License (CCL)
(CC BY)
(CC BY)
