Compact Dual-Wavelength Optical Fiber Sensor for the Simultaneous Measurement of the Refractive Index and Temperature of Liquid Samples
This study proposes the development of a dual-wavelength optical fiber sensor (DWOFS) that integrates two optical fiber structures in a multimode transmission line to measure the refractive index and temperature of a liquid concurrently. One structure is based on a refractive index sensor that utili...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-05-01
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| Series: | Chemosensors |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2227-9040/13/6/198 |
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| Summary: | This study proposes the development of a dual-wavelength optical fiber sensor (DWOFS) that integrates two optical fiber structures in a multimode transmission line to measure the refractive index and temperature of a liquid concurrently. One structure is based on a refractive index sensor that utilizes surface plasmon resonance, comprising a 5 mm long single-mode fiber (SMF) section coated with chromium/gold (Cr/Au) films. The secondary structure employs a multimode interferometer with a 29 mm long no-core fiber (NCF) section covered with a thick layer of polydimethylsiloxane (PDMS) to measure temperature. The measurements obtained reveal two distinct drops in the transmission spectrum at approximately 600 nm and 1550 nm, respectively, enabling precise measurement of the two parameters. The sensor demonstrates a high degree of sensitivity to both refractive index and temperature, spanning the visible (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2770.30</mn><mtext> </mtext><mi mathvariant="normal">n</mi><mi mathvariant="normal">m</mi><mo>/</mo><mi mathvariant="normal">R</mi><mi mathvariant="normal">I</mi><mi mathvariant="normal">U</mi></mrow></semantics></math></inline-formula>) and infrared <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>(</mo><mo>−</mo><mn>0.178</mn><mtext> </mtext><mi mathvariant="normal">n</mi><mi mathvariant="normal">m</mi><mo>/</mo><mo>°</mo><mi mathvariant="normal">C</mi></mrow></semantics></math></inline-formula>) regions of the spectra, respectively. Furthermore, the thermo-optical coefficient for water <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>(</mo><msup><mrow><mo>−</mo><mn>0.9928</mn><mo>×</mo><mn>10</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup><mtext> </mtext><mi mathvariant="normal">R</mi><mi mathvariant="normal">I</mi><mi mathvariant="normal">U</mi><mo>/</mo><mo>°</mo><mi mathvariant="normal">C</mi><mo>)</mo></mrow></semantics></math></inline-formula> was estimated. The proposed sensor offers a compact solution for the simultaneous measurement of refractive index and temperature in liquid samples for a variety of applications, including biological, environmental, and healthcare research. |
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| ISSN: | 2227-9040 |