High performance liquid analyte sensing based on Bloch surface wave resonances in the spectral domain

• Published in: Optics and laser technology 2022-01, Vol.145, p.107492, Article 107492
• Main Authors: Hlubina, P., Gryga, M., Ciprian, D., Pokorny, P., Gembalova, L., Sobota, J.
• Format: Article
• Language: English
• Subjects: Aqueous solutions; Bloch surface wave; Domains; Figure of merit; Liquid analyte sensing; One-dimensional photonic crystal; p- and s-polarized waves; Phase shift; Photonic crystals; Refractivity; Sensitivity; Sensors; Silicon dioxide; Sodium chloride; Spectra; Spectral reflectance; Spectral reflectance and phase; Surface plasmon resonance; Surface waves; Titanium dioxide
• ISSN: 0030-3992; 1879-2545
• DOI: 10.1016/j.optlastec.2021.107492

[Display omitted] •A highly sensitive liquid analyte sensor employing a multilayer structure is designed and realized.•The sensor utilizes Bloch surface wave spectral resonances in both polarizations.•Spectral responses, including the reflectance, phase shift and its derivative are determined for aqueous solutions of NaCl.•High sensitivity to the refractive index changes and high figure of merit were revealed. In this paper, we report a design of a truncated one-dimensional photonic crystal (1DPhC) comprising six bi-layers of TiO2/SiO2 with a termination layer of TiO2 to realize a highly sensitive liquid analyte sensor utilizing Bloch surface wave (BSW) resonances in the spectral domain. We demonstrate that the BSW excitation shows up as a dip for both p- and s-polarized waves. Reflectance response for a p-polarized BSW is due to the spectral interference with maximum depth, and resonance thus obtained is comparable in magnitude with surface plasmon resonance (SPR). In the theoretical analysis, the spectral reflectance, phase difference and its derivative are determined for aqueous solutions of NaCl when the refractive index (RI) is changed in a range of 1.3330–1.3482. We revealed that the BSW resonances for the p-polarized wave give a sensitivity of 1602 nm per RI unit (RIU) and figure of merit (FOM) of 106 RIU−1, respectively. For an s-polarized BSW, they are increased to 1933 nm/RIU and 434 RIU−1, respectively. Moreover, the theoretical results are experimentally verified, and very good agreement is confirmed. The spectral responses for aqueous solutions of NaCl with the RI up to 1.3547 give for the p-polarized BSW a sensitivity of 2022 nm/RIU and FOM of 109 RIU−1, respectively, and using the spectral derivative of the BSW phase difference, the FOM is increased to 301 RIU−1. BSW based sensors with responses in both polarizations thus represent an effective alternative to SPR sensors with advantages including a higher FOM and mechanical robustness.