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Li XW, Sheng J, Wen ZJ et al. Double topological phase singularities in highly absorbing ultra-thin film structures for ultrasensitive humidity sensing. Opto-Electron Adv 8, 240091 (2025). doi: 10.29026/oea.2025.240091
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Double topological phase singularities in highly absorbing ultra-thin film structures for ultrasensitive humidity sensing
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Abstract
Phase singularities (PSs) in topological darkness-based sensors have received significant attention in optical sensing due to their rapid, ultra-sensitive, and label-free detection capabilities. Here, we present both experimental and theoretical investigations of an ultrasensitive and multiplexed phase-sensitive sensor utilizing dual topological PSs in the visible and near-infrared regions. This sensor uses a simple structure, which consists of an ultra-thin highly absorbing film deposited on a metal substrate. We demonstrate the achievement of dual-polarization darkness points for s- and p-polarizations at different incident angles. Furthermore, we theoretically explain the double topological PSs accompanied by a perfect ±π-jump near a zero-reflection point, based on the temporal coupled-mode formalism. To validate its multifunctional capabilities, humidity sensing tests were carried out. The results demonstrate that the sensor has a detection limit reaching the level of 0.12 ‰. These findings go beyond the scope of conventional interference optical coatings and highlight the potential applications of this technology in gas sensing and biosensing domains. -
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References
[1] Ma GT, Shen WF, Sanchez DS et al. Excitons enabled topological phase singularity in a single atomic layer. ACS Nano 17, 17751–17760 (2023). doi: 10.1021/acsnano.3c02478 [2] Sreekanth KV, Elkabbash M, Medwal R et al. Generalized brewster angle effect in thin-film optical absorbers and its application for graphene hydrogen sensing. ACS Photonics 6, 1610–1617 (2019). doi: 10.1021/acsphotonics.9b00564 [3] Samdani S, Kala A, Kaurav R et al. Reusable biosensor based on differential phase detection at the point of darkness. Adv Photonics Res 2, 2000147 (2021). doi: 10.1002/adpr.202000147 [4] Sreekanth KV, Han S, Singh R. Ge2Sb2Te5-based tunable perfect absorber cavity with phase singularity at visible frequencies. Adv Mater 30, 1706696 (2018). doi: 10.1002/adma.201706696 [5] Rao AR, Sreekanth KV, Sreejith S et al. Ultrasensitive detection of heavy metal ions with scalable singular phase thin film optical coatings. Adv Opt Mater 10, 2102623 (2022). doi: 10.1002/adom.202102623 [6] Sreekanth KV, Mahalakshmi P, Han S et al. Brewster mode-enhanced sensing with hyperbolic metamaterial. Adv Opt Mater 7, 1900608 (2019). [7] Sreekanth KV, Sreejith S, Han S et al. Biosensing with the singular phase of an ultrathin metal-dielectric nanophotonic cavity. Nat Commun 9, 369 (2018). doi: 10.1038/s41467-018-02860-6 [8] Berkhout A, Koenderink AF. Perfect absorption and phase singularities in plasmon antenna array etalons. ACS Photonics 6, 2917–2925 (2019). doi: 10.1021/acsphotonics.9b01019 [9] Tan TCW, Plum E, Singh R. Lattice-enhanced fano resonances from bound states in the continuum metasurfaces. Adv Opt Mater 8, 1901572 (2020). doi: 10.1002/adom.201901572 [10] Lim WX, Manjappa M, Pitchappa P et al. Shaping high-Q planar fano resonant metamaterials toward futuristic technologies. Adv Opt Mater 6, 1800502 (2018). doi: 10.1002/adom.201800502 [11] Wang WH, Srivastava YK, Tan TCW et al. Brillouin zone folding driven bound states in the continuum. Nat Commun 14, 2811 (2023). doi: 10.1038/s41467-023-38367-y [12] Cong LQ, Singh R. Spatiotemporal dielectric metasurfaces for unidirectional propagation and reconfigurable steering of terahertz beams. Adv Mater 32, 2001418 (2020). doi: 10.1002/adma.202001418 [13] Gupta M, Singh R. Terahertz sensing with optimized Q/Veff metasurface cavities. Adv Opt Mater 8, 1902025 (2020). doi: 10.1002/adom.201902025 [14] Tian Z, Singh R, Han JG et al. Terahertz superconducting plasmonic hole array. Opt Lett 35, 3586–3588 (2010). doi: 10.1364/OL.35.003586 [15] Liu MQ, Chen WJ, Hu GW et al. Spectral phase singularity and topological behavior in perfect absorption. Phys Rev B 107, L241403 (2023). doi: 10.1103/PhysRevB.107.L241403 [16] Grigorenko AN, Nikitin PI, Kabashin AV. Phase jumps and interferometric surface plasmon resonance imaging. Appl Phys Lett 75, 3917–3919 (1999). doi: 10.1063/1.125493 [17] Hu JY, Wang Y, Niu JB et al. Observation of dual-polarization topological photonic states at optical frequencies. Laser Photonics Rev 17, 2300515 (2023). doi: 10.1002/lpor.202300515 [18] Tselikov GI, Danilov A, Shipunova VO et al. Topological darkness: how to design a metamaterial for optical biosensing with ultrahigh sensitivity. ACS Nano 17, 19338–19348 (2023). doi: 10.1021/acsnano.3c06655 [19] Song HM, Zhang N, Duan J et al. Dispersion topological darkness at multiple wavelengths and polarization states. Adv Opt Mater 5, 1700166 (2017). doi: 10.1002/adom.201700166 [20] Malassis L, Massé P, Tréguer-Delapierre M et al. Topological darkness in self-assembled plasmonic metamaterials. Adv Mater 26, 324–330 (2014). doi: 10.1002/adma.201303426 [21] Kravets VG, Schedin F, Jalil R et al. Singular phase nano-optics in plasmonic metamaterials for label-free single-molecule detection. Nat Mater 12, 304–309 (2013). doi: 10.1038/nmat3537 [22] Ermolaev G, Voronin K, Baranov DG et al. Topological phase singularities in atomically thin high-refractive-index materials. Nat Commun 13, 2049 (2022). doi: 10.1038/s41467-022-29716-4 [23] Ni JC, Huang C, Zhou LM et al. Multidimensional phase singularities in nanophotonics. Science 374, 418 (2021). [24] Yue XZ, Wang T, Yan RQ et al. High-sensitivity refractive index sensing with the singular phase in normal incidence of an asymmetric Fabry–Perot cavity modulated by grating. Opt Laser Technol 157, 108697 (2023). doi: 10.1016/j.optlastec.2022.108697 [25] Cusworth E, Kravets VG, Grigorenko AN. Topological darkness in optical heterostructures: prediction and confirmation. ACS Photonics 10, 3715–3722 (2023). doi: 10.1021/acsphotonics.3c00879 [26] Toksumakov AN, Ermolaev GA, Tatmyshevskiy MK et al. Anomalous optical response of graphene on hexagonal boron nitride substrates. Commun Phys 6, 13 (2023). doi: 10.1038/s42005-023-01129-9 [27] Fonollosa J, Carmona M, Santander J et al. Limits to the integration of filters and lenses on thermoelectric IR detectors by flip-chip techniques. Sens Actuators A Phys 149, 65–73 (2009). doi: 10.1016/j.sna.2008.10.008 [28] Dong M, Zheng CT, Miao SZ et al. Development and measurements of a mid-infrared multi-gas sensor system for CO, CO2 and CH4 detection. Sensors 17, 2221 (2017). doi: 10.3390/s17102221 [29] Anker JN, Hall WP, Lyandres O et al. Biosensing with plasmonic nanosensors. Nat Mater 7, 442–453 (2008). doi: 10.1038/nmat2162 [30] Tan XC, Zhang H, Li JY et al. Non-dispersive infrared multi-gas sensing via nanoantenna integrated narrowband detectors. Nat Commun 11, 5245 (2020). doi: 10.1038/s41467-020-19085-1 [31] Shi X, Ge LX, Liu BY et al. Optical metasurface composed of multiple antennas with anti-Hermitian coupling in a single layer. Opt Lett 46, 2252–2255 (2021). doi: 10.1364/OL.421555 [32] Shi X, Ge LX, Wen XW et al. Broadband light absorption in graphene ribbons by canceling strong coupling at subwavelength scale. Opt Express 24, 26357–26362 (2016). doi: 10.1364/OE.24.026357 [33] Li XW, Wen ZJ, Zhou DJ et al. Inverse design of refractory mid-wave infrared narrowband thermal emitters for optical gas sensing. Cell Rep Phys Sci 4, 101687 (2023). doi: 10.1016/j.xcrp.2023.101687 [34] Lv QH, Jin C, Zhang BC et al. Ultrawide-angle ultralow-reflection phenomenon for transverse electric mode in anisotropic metasurface. Adv Opt Mater 10, 2102400 (2022). doi: 10.1002/adom.202102400 [35] Lavigne G, Caloz C. Generalized brewster effect using bianisotropic metasurfaces. Opt Express 29, 11361–11370 (2021). doi: 10.1364/OE.423078 [36] Zhang Z, Che ZY, Liang XY et al. Realizing generalized brewster effect by generalized kerker effect. Phys Rev Appl 16, 054017 (2021). doi: 10.1103/PhysRevApplied.16.054017 [37] Tamayama Y, Nakanishi T, Sugiyama K et al. Observation of brewster’s effect for transverse-electric electromagnetic waves in metamaterials: experiment and theory. Phys Rev B 73, 193104 (2006). doi: 10.1103/PhysRevB.73.193104 [38] Watanabe R, Iwanaga M, Ishihara T. S-polarization brewster’s angle of stratified metal-dielectric metamaterial in optical regime. Phys Status Solidi Res 245, 2696–2701 (2008). doi: 10.1002/pssb.200879899 [39] Kats MA, Blanchard R, Genevet P et al. Nanometre optical coatings based on strong interference effects in highly absorbing media. Nat Mater 12, 20–24 (2013). doi: 10.1038/nmat3443 [40] Pan H, Wen ZJ, Tang ZH et al. Wide gamut, angle-insensitive structural colors based on deep-subwavelength bilayer media. Nanophotonics 9, 3385–3392 (2020). doi: 10.1515/nanoph-2020-0106 [41] Tompkins HG, Hilfiker JN. Spectroscopic Ellipsometry: Practical Application to Thin Film Characterization (Momentum Press, New York, 2016). [42] Fan SH, Suh W, Joannopoulos JD. Temporal coupled-mode theory for the fano resonance in optical resonators. J Opt Soc Am A Opt Image Sci Vis 20, 569–572 (2003). doi: 10.1364/JOSAA.20.000569 [43] Suh W, Wang Z, Fan SH. Temporal coupled-mode theory and the presence of non-orthogonal modes in lossless multimode cavities. IEEE J Quantum Electron 40, 1511–1518 (2004). doi: 10.1109/JQE.2004.834773 [44] Wang B, Liu WZ, Zhao MX et al. Generating optical vortex beams by momentum-space polarization vortices centred at bound states in the continuum. Nat Photonics 14, 623–628 (2020). doi: 10.1038/s41566-020-0658-1 [45] Wang ZJ, Dai CJ, Zhang J et al. Real-time tunable nanoprinting-multiplexing with simultaneous meta-holography displays by stepwise nanocavities. Adv Funct Mater 32, 2110022 (2022). doi: 10.1002/adfm.202110022 [46] Zhang J, Huang C, Chen YX et al. Polyvinyl alcohol: a high-resolution hydrogel resist for humidity-sensitive micro-/nanostructure. Nanotechnology 31, 425303 (2020). doi: 10.1088/1361-6528/ab9da7 -
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Li XW, Sheng J, Wen ZJ et al. Double topological phase singularities in highly absorbing ultra-thin film structures for ultrasensitive humidity sensing. Opto-Electron Adv 8, 240091 (2025). doi: 10.29026/oea.2025.240091
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Figure 1.
Theoretical predictions of double topological darkness (zero-reflections). (a) Schematics of light reflection for observing PSs from the ultra-thin absorbing dielectric on a metal substrate. The effective medium layer (EML) has fixed thickness. (b) The yellow point of intersection of spectral dispersion curve n(λ), k(λ) of the top layer Ge with the ZRS with a blue point for p-polarized light and ZRS with a red point for s-polarized light are topologically protected.
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Figure 2.
Double topological PS effect in ultra-thin absorbing dielectric structures. Schematic of the Ge (26 nm)/Ag system exhibiting: (a) p-polarized topological darkness point effect, and (b) s-polarized topological darkness point effect. TMM calculated angular reflectivity spectra for: (c) p-polarized and (d) s-polarized reflectance spectrum of the thin-film absorber. (e, f) Show the reflectance measurements, respectively. The yellow circle regions refer to wavelength and angle pairs where the polarization darkness points occur for p-polarized light and s-polarized light. Reflectance spectra are shown for p-polarization at (g) 80.2° and for s-polarization at 29.4°, with measured data represented by hollow triangles and calculated data by solid lines.
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Figure 3.
Experimental observation of PSs. (a−c) Simulated and (b−d) experimental ellipsometric parameters amplitude (Ψ) and phase (Δ) for Ge (26 nm)/Ag system. The yellow circle regions refer to wavelength and angle pairs where the topological PSs for p-polarized light (Ψ = 0° at 80.2° 587.8 nm) and s-polarized light (Ψ = 90° at 29.4° 937.1 nm) occur. (e, f) Ellipsometry parameters Ψ and Δ at the above two angles (80.2° and 29.4°) for p- and s-polarized light, represented by solid circles for measured data and solid lines for TMM calculations.
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Figure 4.
Topological nature of darkness points associated with spectral PSs. (a) Schematic of the multi-port multimode system. (b) Analyses using a multiple scattering model along with the thin-film system to determine the typical reflection phase. (c, d) Investigation of the ellipsometry parameters Ψ and Δ at the aforementioned angles (80.2° and 29.4°) for p- and s-polarized light, measured with solid circles and calculated using TCMT represented by solid line.
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Figure 5.
Double topological PSs in ultrathin absorbing dielectric structures with PVA film. Schematic of the PVA (40 nm)/Ge (26 nm)/Ag system exhibiting (a) the p-polarized topological darkness point effect and (b) the s-polarized topological darkness point effect. (c, d) Investigation of the ellipsometry parameters Ψ and Δ at the aforementioned angles (73.0° and 48.0°) for p- and s-polarized light, measured with solid circles and calculated using TMM represented by solid lines.
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Figure 6.
Humidity sensor based on topology of PVA film on Ge/Ag. (a, b) The dependence of ellipsometric parameters Δ and Ψ on the humidity of air recorded at the incidence angle of 73.0° with p-polarization topological darkness points, corresponding to the PS. The insets show the magnified view of Δ and Ψ. (c) The jump of Δ with increased humidity at λ = 734.3 nm to 741.6 nm. The error bars represent the standard deviation of multiple measurements. (d) Spectral shift of the resonance position of Ψ spectrum with increased humidity of air.
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Figure 7.
Humidity sensor based on topology of PVA film on Ge/Ag. (a, b) The dependence of ellipsometric parameters Δ and Ψ on the humidity of air recorded at the incidence angle of 48.0° with s-polarization topological darkness points, corresponding to the PS. The insets show the magnified view of Δ and Ψ. (c) The jump of Δ with increased humidity at λ = 937.8 nm to 940.7 nm. The error bars represent the standard deviation of multiple measurements. (d) Spectral shift of the resonance position of Ψ spectrum with increased humidity of air.
