<p>We propose an anchor-shaped dual-channel photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR) for simultaneous ultrawide-range detection of temperature and refractive index (RI) variations. The sensor features an asymmetric anchor-shaped cross-section with orthogonally polished semi-circular surfaces, selectively coated with gold and polydimethylsiloxane (PDMS) films. This structural configuration enables polarization-resolved SPR excitation, facilitating independent coupling of higher-order modes <InlineEquation ID="IEq1"> <EquationSource Format="TEX">${LP}_{11\text{a}}^{x}$</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mrow> <mi mathvariant="italic">LP</mi> </mrow> <mrow> <mn>11</mn> <mtext>a</mtext> </mrow> <mi>x</mi> </msubsup> </math></EquationSource> </InlineEquation> (x-polarized) and <InlineEquation ID="IEq2"> <EquationSource Format="TEX">${LP}_{11b}^{y}$</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mrow> <mi mathvariant="italic">LP</mi> </mrow> <mrow> <mn>11</mn> <mi>b</mi> </mrow> <mi>y</mi> </msubsup> </math></EquationSource> </InlineEquation> (y-polarized) for dual-parameter sensing. The x-polarized channel, coated with both gold and PDMS, responds to changes in RI and temperature, while the y-polarized channel, coated solely with gold, targets RI sensing of another analyte. COMSOL-based simulations optimize structural parameters to ensure strong plasmonic coupling, effective mode confinement, and efficient higher-order mode excitation across both channels. The proposed sensor achieves a wide RI detection range from 1.21 to 1.44 and a wide temperature detection range from − 100 to 100 °C, with a maximum RI sensitivity of 14,500 nm/RIU and a temperature sensitivity of 4 nm/°C. These results demonstrate the sensor’s strong potential for practical applications, including real-time cancer cell detection, biochemical analysis, and multi-parameter monitoring in complex biological and chemical environments.</p>

Anchor-Shaped Dual-Channel PCF Sensor Based on SPR for Simultaneous Ultrawide-Range Refractive Index and Temperature Detection with Dual-Polarization Higher-Order Mode Excitation

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发表日期：

2025年7月19日

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Yimin Mao,
Xiang Lu,
Zhao Zhang,
Yujia Wang,
Fang Ren

摘要

We propose an anchor-shaped dual-channel photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR) for simultaneous ultrawide-range detection of temperature and refractive index (RI) variations. The sensor features an asymmetric anchor-shaped cross-section with orthogonally polished semi-circular surfaces, selectively coated with gold and polydimethylsiloxane (PDMS) films. This structural configuration enables polarization-resolved SPR excitation, facilitating independent coupling of higher-order modes ${LP}_{11\text{a}}^{x}$ ${LP}_{11 a}^{x}$ (x-polarized) and ${LP}_{11b}^{y}$ ${LP}_{11 b}^{y}$ (y-polarized) for dual-parameter sensing. The x-polarized channel, coated with both gold and PDMS, responds to changes in RI and temperature, while the y-polarized channel, coated solely with gold, targets RI sensing of another analyte. COMSOL-based simulations optimize structural parameters to ensure strong plasmonic coupling, effective mode confinement, and efficient higher-order mode excitation across both channels. The proposed sensor achieves a wide RI detection range from 1.21 to 1.44 and a wide temperature detection range from − 100 to 100 °C, with a maximum RI sensitivity of 14,500 nm/RIU and a temperature sensitivity of 4 nm/°C. These results demonstrate the sensor’s strong potential for practical applications, including real-time cancer cell detection, biochemical analysis, and multi-parameter monitoring in complex biological and chemical environments.