Ultra-characteristic multimode fiber parallel sensing system capable of synchronously exciting SPR

Abstract

The present invention relates to an optical fiber sensing system, and more specifically, to an ultra-characteristic multi-single-mode optical fiber parallel sensing system capable of synchronously exciting SPR. The parallel sensing system comprises three parallel single-mode optical fibers, each consisting of a cladding and a core. The claddings of the single-mode optical fibers on both sides are polished on one side, while the cladding of the middle single-mode optical fiber is polished on both sides. The polished surface of the cladding is coated with a gold film. The cladding radius is 7.5 mm, the core radius is 4.1 mm, the gold film thickness is 40 nm, the background material of the cladding is silica, and the single-mode optical fibers are index-guided fibers. The optical fiber sensing system has excellent optical performance, a simple manufacturing process, and strong robustness.

Description

Technical field:

[0002] The present invention relates to an optical fiber sensing system, in particular to a super-characteristic Multi-SMFs (multi-single-mode optical fibers) parallel sensing system capable of synchronously exciting SPR. Background technology:

[0004] With the growing demand for measuring sample refractive index in fields such as biochemical research, medical diagnostics, materials science, nanophotonics, and environmental monitoring, SPR technology has been widely applied in optical sensing research. Surface plasmon resonance (SPR) is a unique physical optical phenomenon involving the resonant excitation of electromagnetic surface waves and the collective oscillation of free electrons in metals. When excited at the metal-dielectric interface, the electromagnetic wave energy is absorbed, resulting in a narrow absorption peak at the resonant wavelength. This absorption peak is extremely sensitive to minute changes in the refractive index of the surrounding medium, effectively responding rapidly to the sample being measured and achieving high sensitivity and resolution. Therefore, due to its outstanding characteristics such as real-time label-free monitoring, excellent output characteristics, high selectivity, and low detection cost, it has attracted widespread attention and is widely used in the detection and analysis of samples in chemistry, biology, medicine, and their interdisciplinary fields.

[0005] In recent years, various types of SPR sensing platforms have been proposed, categorized by excitation method as prism, fiber, and grating. While prism-based SPR sensing platforms have achieved some commercial application due to their advantages, such as high sensitivity, good stability, and ease of excitation, this prism-coupled structure suffers from drawbacks such as bulky measurement systems, large sensor elements, and the inability to remotely monitor them. This inability to meet the demands of miniaturization, integration, and intelligent development has limited its widespread application. To address these challenges, fiber-based SPR sensing structures coated with surface plasmon materials have gained increasing attention. An optical fiber is a cylindrical waveguide composed of a core and a cladding. The core has a higher refractive index than the cladding, and light waves propagating through the fiber are confined by total internal reflection at the core-cladding interface. This fiber-based SPR sensing structure is not only compact, requires minimal sample volume, and eliminates the need for large prisms, but also offers remote monitoring capabilities. This opens new avenues for miniaturization of SPR sensors and promotes the rapid development of various fiber-based SPR sensing technologies.

[0006] Fiber-based SPR sensors can be further categorized as single-mode fiber, multimode fiber, fiber Bragg grating, tilted fiber Bragg grating, and photonic crystal fiber. Among the numerous fiber-based SPR sensors, single-mode fiber and photonic crystal fiber have attracted considerable attention. The advantages of the former lie in its low cost, mature commercial manufacturing, and strong resistance to interference from harsh environments. However, the sensitivity and resolution of SPR sensors based on single-mode fiber are relatively poor. Photonic crystal fiber-based SPR sensors, on the other hand, have sparked a wave of research due to their flexible arrangement of air holes in their cladding and structural design, adjustable chromatic dispersion, and excellent nonlinearity. Various optimized structures have been proposed, but their disadvantages lie in the difficulty of achieving process manufacturing and mass production of different structures as required, the high cost, and the susceptibility of air holes within the fiber to collapse due to interference from the external environment. Summary of the invention:

[0008] The present invention remedies and improves the deficiencies of the above-mentioned prior art and provides a super-characteristic Multi-SMFs (multiple single-mode fibers) parallel sensing system that can synchronously excite SPR. The fiber optic sensing system has good optical performance, simple manufacturing process and strong robustness.

[0009] The technical solution adopted by the present invention is: a super-characteristic Multi-SMFs parallel sensing system capable of synchronously exciting SPR, wherein the parallel sensing system is composed of three parallel single-mode optical fibers, each of which consists of a cladding and a core. The claddings of the single-mode optical fibers on both sides are polished on one side, and the cladding of the single-mode optical fiber in the middle is polished on both sides. The polished surface of the cladding is coated with a gold film; the radius of the cladding is 7.5 mm, the radius of the core is 4.1 mm, and the thickness of the gold film is 40 nm.

[0010] Furthermore, the background material of the cladding is silicon dioxide.

[0011] Furthermore, the single-mode optical fiber is a refractive index guided optical fiber.

[0012] Furthermore, a super-characteristic Multi-SMFs parallel sensing system (SPR and Multi-SMFs are the abbreviations of surface plasmon resonance and multi-single-mode fiber, respectively) that can simultaneously excite SPR is developed. The super-characteristic sensing system consists of three single-mode optical fibers that are polished and coated with a gold film on the polished surface. The cladding is etched to a suitable radius and then polished. The gold film is coated on the polished surface of the optical fiber. The three single-mode optical fibers are connected in parallel to form a super-characteristic sensing system that can synchronously excite SPR.

[0013] The present invention provides a super-characteristic Multi-SMFs (multiple single-mode fibers) parallel sensing system capable of synchronously exciting SPR. This fiber sensing system has excellent optical performance, simple manufacturing process, and strong robustness. Its main advantages are as follows:

[0014] (1) The refractive index range of the detectable analytes is 1.00-1.44, which makes it possible to simultaneously detect gas and liquid substances over a large range;

[0015] (2) The operable working band is 1200-6900 nm, which greatly broadens the transmittable range of infrared light waves;

[0016] (3) Achieve rapid response to the analyte to be tested and continuously output good optical properties. The optimal sensitivity, average sensitivity, and maximum resolution can reach 50000 nm / RIU, 12906.98 nm / RIU, and 2×10 -6 In particular, in existing studies, it is not common to achieve an average sensitivity of more than 10,000 nm / RIU within a wide refractive index detection range of analyzed samples (1.00-1.44);

[0017] (4) It effectively compensates for the practical difficulties in manufacturing special optical fiber sensing systems and greatly improves the super-characteristic expression of ordinary single-mode optical fibers in the detection of the refractive index of analytical samples;

[0018] (5) The sensor system has a reasonable structural design and is easy to manufacture and apply in multiple fields. Description of the drawings:

[0020] Figure 1 is a cross-sectional schematic diagram of the parallel sensing system in Example 1;

[0021] Figure 2 is a front view of the parallel sensing system in Example 1;

[0022] Figure 3 is a graph showing the relationship between each limiting loss and the resonance wavelength when the refractive index is within the range of 1.00-1.09 when the sensing system in Example 1 detects and analyzes a sample;

[0023] Figure 4 is a graph showing the relationship between each limiting loss and the resonance wavelength when the refractive index is in the range of 1.10-1.19 when the sensing system in Example 1 detects and analyzes a sample;

[0024] Figure 5 is a graph showing the relationship between each limiting loss and the resonance wavelength when the refractive index is within the range of 1.20-1.29 when the sensing system in Example 1 detects and analyzes a sample;

[0025] Figure 6 is a graph showing the relationship between each limiting loss and the resonance wavelength when the refractive index is within the range of 1.30-1.39 when the sensing system in Example 1 detects and analyzes a sample;

[0026] Figure 7 This is a graph showing the relationship between the limiting losses and the resonance wavelength when the refractive index is in the range of 1.40-1.44 when the sensing system in Example 1 detects an analyte sample. Specific implementation method:

[0028] Reference Figure 1 , a super-characteristic Multi-SMFs (multi-single-mode fiber) parallel sensing system that can synchronously excite SPR, the parallel sensing system consists of three parallel single-mode optical fibers, the single-mode optical fibers consist of a cladding 1 and a core 2, the cladding 1 of the single-mode optical fibers on both sides is polished on one side, and the cladding 1 of the middle single-mode optical fiber is polished on both sides, and the polished surface of the cladding 1 is coated with a gold film 3; the radius of the cladding 1 is 7.5mm, the radius of the core 2 is 4.1mm, the thickness of the gold film 3 is 40nm, the background material of the cladding 1 is silica, and the single-mode optical fiber is a refractive index-guided optical fiber.

[0029] The Multi-SMFs parallel sensing system, which enables simultaneous SPR excitation, is a fiber-optic sensing system consisting of three single-mode optical fibers connected in parallel. The Multi-SMFs-SPR sensing system utilizes a gold film coated on the surface of the optical fibers as the sensing layer. The gold film is applied to the polished outer surface of the cladding, and the sample to be measured is placed outside the gold film. When polarized light from a light source is incident on the single-mode optical fibers, light of different wavelengths propagates synchronously along the axis of the three single-mode optical fibers in specific patterns, while surface plasmon waves propagate in a fixed pattern within the gold film. When light of a certain wavelength within the single-mode optical fiber and the surface plasmon waves within the gold film on the outer cladding share the same wave vector, energy coupling occurs. Due to the unique design of the parallel structure, both self-coupling and mutual coupling mechanisms coexist. Light energy within the single-mode optical fiber is coupled into the gold film, reducing the energy within the single-mode optical fiber, resulting in energy loss within the single-mode optical fiber. The wavelength corresponding to the maximum energy loss is the resonant wavelength. Based on the relationship between energy loss and light wavelength, the energy loss spectrum is drawn. Figure 3-Figure 7The limiting loss plots of the sensing system for refractive indices ranging from 1.00 to 1.44 are presented. As can be seen from the plots, as the refractive index of the sample outside the gold film increases by 0.01, the resonance wavelength decreases, exhibiting a blueshift and a gradual decrease in the resonance peak. Analysis of the plots reveals that the sensing system exhibits high sensitivity across all refractive indices, with optimal and average sensitivities reaching 50,000 nm / RIU and 12,906.98 nm / RIU, respectively. In particular, achieving an average sensitivity exceeding 10,000 nm / RIU across the broad refractive index range (1.00-1.44) is uncommon in existing research, and this achievement holds significant research significance and practical value for applications in practical engineering and other fields. In summary, this parallel sensing system exhibits outstanding advantages and features, including a rational structural design, ease of fabrication, and multi-disciplinary application.

Claims

1. A super-characteristic multi-single-mode optical fiber parallel sensing system capable of synchronously exciting SPR, characterized by: The super-characteristic Multi-SMFs parallel sensing system capable of synchronously exciting SPR is composed of three parallel single-mode optical fibers, wherein the single-mode optical fibers are composed of a cladding (1) and a core (2), wherein the cladding (1) of the single-mode optical fibers on both sides is polished on one side, and the cladding (1) of the single-mode optical fiber in the middle is polished on both sides, and the polished surface of the cladding (1) is coated with a gold film (3); the radius of the cladding (1) is 7.5 mm, the radius of the core (2) is 4.1 mm, and the thickness of the gold film (3) is 40 nm.

2. The ultra-characteristic multi-single-mode optical fiber parallel sensing system capable of synchronously exciting SPR according to claim 1, characterized in that: The background material of the cladding (1) is silicon dioxide.

3. The ultra-characteristic multi-single-mode optical fiber parallel sensing system capable of synchronously exciting SPR according to claim 1, characterized in that: The single-mode optical fiber is a refractive index guided optical fiber.

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