Multi-Channel Simultaneous Measurement of Cu(II) and Zn(II) Metal Ions Using Multimode Interference Based Sensors Encompassed in Fiber Ring Laser

• Published in: IEEE photonics journal Vol. 16; no. 2; pp. 1 - 8
• Main Authors: N, Anuradha, S, Sivabalan
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01-04-2024; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aqueous solutions; Configurations; Copper; Copper ions concentration; Few mode fiber; Fiber lasers; Fiber optics; Fiber ring laser cavity; Interference; Ions; Metals; Multi-channel RI sensing; Multimode interference; Optical fiber sensors; Optical fibers; Ring lasers; Sensitivity; Sensor phenomena and characterization; Sensors; Zinc; Zinc ions concentration
• ISSN: 1943-0655; 1943-0647
• DOI: 10.1109/JPHOT.2024.3365422

In this research, a novel fiber-optic multimode interference based multi-channel transmissive sensors integrated into a fiber laser loop (FRL) for the detection of <inline-formula><tex-math notation="LaTeX">\text{Cu}^{2+}</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">\text{Zn}^{2+}</tex-math></inline-formula> metal ions in aqueous solution is proposed and experimentally corroborated. The multi-channel configuration includes single mode- claddingless- graded index multimode- single mode (SCGS) fiber structure and single mode- claddingless- few mode- single mode fiber (SCFS) combination in parallel for tracing <inline-formula><tex-math notation="LaTeX">\text{Cu}^{2+}</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">\text{Zn}^{2+}</tex-math></inline-formula> metal ions simultaneously and implemented in FRL setup to enhance the optical sensing characteristics. The sensing probe utilises the self-imaging effect to detect and measure the concentrations of two different metal ions. The SCGS structure has achieved a sensitivity of <inline-formula><tex-math notation="LaTeX">4.347 \times 10^{-4}</tex-math></inline-formula> nm/nM and a coefficient of determination <inline-formula><tex-math notation="LaTeX">\mathrm{R}^{2}</tex-math></inline-formula> value of 0.9922. The SCFS combination, on the other hand, has attained a sensitivity of <inline-formula><tex-math notation="LaTeX">4.358 \times 10^{-4}</tex-math></inline-formula> nm/nM and a <inline-formula><tex-math notation="LaTeX">\mathrm{R}^{2}</tex-math></inline-formula> value of 0.99277. The proposed sensing configuration holds promise for multi-point sensing in bio and chemical applications, particularly in real-time scenarios.