Double-parameter photonic crystal fiber sensor based on surface plasma resonance
By coating gold film and tantalum pentoxide film on the groove channel of the photonic crystal fiber sensor to stimulate surface plasmon resonance, the problem that traditional sensors are difficult to achieve multi-parameter detection is solved, and high-sensitivity and high-resolution dual-parameter measurement is achieved, which is suitable for biomedical and industrial non-destructive testing.
Patent Information
- Application Number
- CN202510655510.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-21
- Publication Date
- 2025-10-03
AI Technical Summary
Traditional optical sensors have difficulty achieving multi-parameter detection in complex environments, especially in biomedical testing and industrial monitoring, where the need to simultaneously track changes in multiple physical quantities is unmet.
A dual-parameter photonic crystal fiber sensor based on surface plasmon resonance is designed. By coating the groove channel surface with gold film and tantalum pentoxide film, the SPR effect is stimulated, the resonance effect is enhanced, and the sensitivity and resolution of the sensor are improved.
It realizes dual-channel sensing of the refractive index of the analytical liquid to be tested and the temperature of the thermosensitive liquid. The sensitivity and resolution are better than those of existing sensors and are suitable for biomedical and industrial non-destructive testing.
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Figure CN120741409A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of optical fiber sensors, and in particular to a dual-parameter photonic crystal optical fiber sensor based on surface plasmon resonance. Background Art
[0002] Photonic crystal fiber (PCF) sensors are a novel sensing technology based on microstructured optical fibers. Their core principle is to manipulate light propagation characteristics through periodically arranged air holes or high-refractive-index materials within the fiber, enabling highly sensitive detection of parameters such as temperature, magnetic field, and refractive index. These sensors are widely used in biomedical applications, such as detecting biomolecule concentrations; in environmental monitoring, for monitoring water pollutants and harmful air gases; in food safety testing, for detecting harmful substances such as food additives; and in chemical analysis, for analyzing the purity of chemical substances.
[0003] Surface plasmon resonance (SPR) is a physical phenomenon at the metal-dielectric interface. When light is incident from a denser medium into a less dense medium, an evanescent wave is generated under certain conditions. This wave couples with free electrons on the metal surface to excite surface plasmon waves (SPWs). When the wave vector of the incident light matches that of the SPW, resonant energy transfer occurs, resulting in a significant attenuation of the reflected light intensity and the formation of a characteristic resonance peak in the spectrum. The position of this resonance peak is highly sensitive to changes in the refractive index of the medium at the interface. Even small changes in the refractive index can cause the peak position to shift, enabling high-precision refractive index detection. Photonic crystal fibers, with their periodic air hole structure and tunable geometric parameters, provide a flexible design space for SPR sensors, significantly improving the sensitivity and detection performance of the sensors.
[0004] With the development of society, the demand for multi-parameter sensing is growing. Traditional optical sensors often face the limitations of single-parameter detection in complex environments, while practical application scenarios (such as biomedical testing and industrial monitoring) require the simultaneous tracking of changes in multiple physical quantities. Summary of the Invention
[0005] The purpose of the present invention is to provide a dual-parameter photonic crystal fiber sensor based on surface plasmon resonance. By coating a gold film and a tantalum pentoxide film on the surface of a groove channel to stimulate the SPR effect, the resonance effect is effectively enhanced, and the sensitivity and resolution of the sensor are improved.
[0006] To achieve the above objectives, the present invention provides a dual-parameter photonic crystal fiber sensor based on surface plasmon resonance, comprising a fiber core and a perfectly matched layer coated on the outside of the fiber core. The fiber core is provided with periodically arranged circular air holes of different sizes. The upper and lower sides of the fiber core are provided with two parallel cut surfaces formed by polishing. The fiber core has two groove channels respectively formed in a direction from the cut surface toward the center. The surface of the upper groove channel is coated with a gold film, and the surface of the lower groove channel is coated with a gold film and a tantalum pentoxide film. An analyte layer is filled between the upper and lower sides of the fiber core and the perfectly matched layer.
[0007] Wherein, the material of the fiber core is fused silica with a refractive index n=1.45.
[0008] Wherein, the radius of the perfectly matched layer is r pml =6um; the radius of the fiber core is r0=5.5um.
[0009] The circular air holes include 16 large circular air holes and 4 small circular air holes, and the circular air holes are symmetrically distributed in the fiber core; the period between the large circular air holes is Λ=2um, the period between the small circular air holes and the distance between the small circular air holes and the center of the fiber core is Λ s =1.75um.
[0010] The large circular air holes are arranged in an array, and the air refractive index n of the large circular air holes is air =1, aperture size d = 1.55um; the small circular air hole is arranged parallel to the groove channel, and the air refractive index n of the small circular air hole air =1, aperture size d s =0.7um.
[0011] The depth of the two groove channels is H = 2.8um, and the width is d w =2.1um.
[0012] The thickness of the gold film coated on the surface of the groove channel is t Au = 28nm, the thickness of the tantalum pentoxide film coated on the gold film layer in the lower groove channel is t Ta2o5 =10nm.
[0013] The analyte layer is divided into a first analyte layer and a second analyte layer. The refractive index range of the solution to be tested in the first analyte layer is 1.38-1.4, and the temperature measurement range of the temperature-sensitive liquid in the second analyte layer is 20-40°C.
[0014] The gold film layer and the tantalum pentoxide film layer generate surface plasmon resonance under the action of Y polarization.
[0015] The present invention provides a dual-parameter photonic crystal fiber sensor based on surface plasmon resonance, comprising a fiber core and a perfectly matched layer coated on the outside of the fiber core, with circular air holes of different sizes symmetrically distributed in the fiber core; the fiber core is provided with a dual-groove channel, the surface of the upper groove channel is coated with a gold film, and the surface of the lower groove channel is coated with a gold film and a tantalum pentoxide film. As the refractive index of the analytical fluid to be tested and the temperature of the thermosensitive liquid change, the wavelength of the resonance peak of the transmission loss spectrum also changes. This sensor realizes dual-channel sensing and dual-parameter measurement. The refractive index range of the analytical fluid sample to be tested is 1.38 to 1.4, and a sensitivity of 5000nm / RIU and a 2×10 -5 The RIU has a resolution of 0.024°C and a sensitivity of 4.2 nm / °C for temperature-sensitive liquids measuring between 20°C and 40°C. The sensor has superior sensitivity and resolution to existing sensors and has great potential for application in fields such as biomedicine and industrial nondestructive testing. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0017] Figure 1 It is a structural schematic diagram of the cross section of a dual-parameter photonic crystal fiber sensor based on surface plasmon resonance of the present invention.
[0018] Figure 2 Schematic diagram of the mode field distribution of the fundamental mode of a specific embodiment of the present invention.
[0019] Figure 3 Schematic diagram of the mode field distribution of the SPP mode according to a specific embodiment of the present invention.
[0020] Figure 4 Schematic diagram of the mode field distribution at the phase matching point of a specific embodiment of the present invention.
[0021] Figure 5 Schematic diagram of the loss when the refractive index of the analyte changes from 1.38 to 1.4 in a specific embodiment of the present invention.
[0022] Figure 6 Schematic diagram of the loss when the temperature of the temperature-sensitive liquid changes from 20°C to 40°C in a specific embodiment of the present invention.
[0023] 1-first analyte layer, 2-upper groove gold film layer, 3-small circular air hole, 4-large circular air hole, 5-lower groove gold film layer, 6-tantalum pentoxide film layer, 7-perfectly matched layer, 8-fiber core, 9-second analyte layer. DETAILED DESCRIPTION
[0024] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.
[0025] See also Figure 1 The present invention provides a dual-parameter photonic crystal fiber sensor based on surface plasmon resonance, comprising a fiber core and a perfectly matched layer coated on the outside of the fiber core. The fiber core is provided with periodically arranged circular air holes of different sizes. The upper and lower sides of the fiber core are provided with two mutually parallel cut surfaces that are polished. The fiber core is provided with two groove channels respectively from the cut surface toward the center. The surface of the upper groove channel is coated with a gold film, and the surface of the lower groove channel is coated with a gold film and a tantalum pentoxide film. An analyte layer is filled between the upper and lower sides of the fiber core and the perfectly matched layer.
[0026] The material of the fiber core is fused silica with a refractive index n=1.45.
[0027] The radius of the perfectly matched layer is r pml =6um; the radius of the fiber core is r0=5.5um.
[0028] The circular air holes include 16 large circular air holes and 4 small circular air holes, and the circular air holes are symmetrically distributed in the fiber core; the period between the large circular air holes is Λ=2um, the period between the small circular air holes and the distance between the small circular air holes and the center of the fiber core is Λ s =1.75um.
[0029] The large circular air holes are arranged in an array, and the air refractive index n of the large circular air holes is air =1, aperture size d = 1.55um; the small circular air hole is arranged parallel to the groove channel, and the air refractive index n of the small circular air hole air =1, aperture size d s =0.7um.
[0030] The depth of the two groove channels is H = 2.8um, and the width is d w =2.1um.
[0031] The surface of the groove channel is coated with a gold film with a thickness t Au= 28nm, the thickness of the tantalum pentoxide film coated on the gold film layer in the lower groove channel is t Ta2o5 =10nm.
[0032] The analyte layer is divided into a first analyte layer and a second analyte layer. The refractive index range of the solution to be tested in the first analyte layer is 1.38-1.4, and the temperature measurement range of the temperature-sensitive liquid in the second analyte layer is 20-40°C.
[0033] The present invention coats the double groove channel with a film thickness of t Au =28nm gold film layer and the film thickness t on the gold film layer of the lower groove channel Ta2o5 =10nm tantalum pentoxide film layer for excitation, which can enhance the resonance effect and make SPR more sensitive to changes in the analyte solution, while adjusting the SPR peak to reduce the crosstalk between the two sensing channels.
[0034] The following is further described with reference to specific embodiments:
[0035] like Figure 2 Shown is a schematic diagram of the mode field distribution of the fundamental mode.
[0036] like Figure 3 As shown, Figure 3 (a) is the surface plasmon polariton (SPP) pattern of the upper groove channel. Figure 3 (b) is the SPP mode diagram of the lower groove channel.
[0037] like Figure 4 As shown in Figure 1, when the phase matching condition is met, the energy in the fiber core couples to the plasma on the metal surface, causing the core energy to decrease. The excitation of the surface plasmon at this point can be characterized by calculating the confinement loss of the core mode. The wavelength corresponding to this point is the resonant wavelength.
[0038] like Figure 4 As shown, Figure 4 In (a), it can be seen that the first analyte layer achieves mode coupling with the fiber core, and the second analyte layer does not respond, indicating that the upper groove channel only responds to changes in the refractive index. Figure 4 In (b), the second analyte layer achieves mode coupling with the fiber core, while the first analyte layer remains unresponsive, indicating that the lower groove channel responds only to temperature changes. This phenomenon confirms that the responses of the upper and lower sensing channels are independent and do not interfere with each other, thus enabling dual-parameter measurement of refractive index and temperature.
[0039] like Figure 5As shown in the figure, when the refractive index of the measured liquid changes from 1.38 to 1.4, the resonance loss peak shifts toward longer wavelengths as the refractive index increases, red-shifting and decreasing. When the refractive index of the measured liquid changes by Δn = 0.01, the loss absorption peak shifts by Δλ. The sensitivity S and resolution R of the sensor can be calculated by calculation.
[0040] like Figure 6 As shown in the figure, when the temperature of the temperature-sensitive liquid changes from 20°C to 40°C, the resonance loss peak shifts toward shorter wavelengths as the refractive index increases, blue-shifting and increasing the loss peak. When the refractive index of the measured liquid changes by ΔT = 10°C, the loss absorption peak shifts by Δλ. The sensitivity S and resolution R of the sensor can be calculated by calculation.
[0041] Depend on Figure 5 It can be seen that the position of the loss absorption peak changes by Δλ = 50 nm. The calculated sensitivity S = 5000 nm / RIU corresponds to a resolution R = 2 × 10 -5 RIU.
[0042] Depend on Figure 6 It can be seen that the position of the loss absorption peak changes by Δλ = 42 nm, and the calculated sensitivity is S = 4.2 nm / °C, corresponding to a resolution R = 0.024°C.
[0043] In summary, compared with the prior art, the present invention has the following beneficial results:
[0044] 1. By adding 4 small circular air holes of the same size in the inner layer of the fiber core, the coupling direction of the core mode and the SPP mode is guided. The presence of the small circular air holes reduces the n of the core mode. eff , which improves the coupling degree between the core mode and the SPP mode.
[0045] 2. By coating the double groove channel with gold film, the coupling between the core mode and the SPP mode is improved.
[0046] 3. By coating a tantalum pentoxide film on the gold film layer of the lower groove channel, the SPR peak can be adjusted to reduce the crosstalk between the two sensing channels.
[0047] 4. Through the double groove structure design, under the action of Y polarization, the refractive index range of the medium to be measured is 1.38-1.4, the maximum wavelength sensitivity is 5000nm / RIU, and the maximum resolution is 2×10 -5 RIU; the temperature measurement range of the medium to be measured is 20-40℃, the maximum wavelength sensitivity is 4.2nm / ℃, and the maximum resolution is 0.024℃.
[0048] The above disclosure is merely one or more preferred embodiments of the present invention, and certainly cannot be used to limit the scope of the present invention. A person skilled in the art can understand that all or part of the processes of the above embodiments and equivalent changes made in accordance with the claims of the present invention still fall within the scope of the invention.
Claims
1. A dual-parameter photonic crystal fiber sensor based on surface plasmon resonance, characterized in that: The fiber core comprises a fiber core and a perfectly matched layer covering the outside of the fiber core. The fiber core is provided with periodically arranged circular air holes of different sizes. The upper and lower sides of the fiber core are provided with two mutually parallel cut surfaces that are polished. The fiber core is provided with two groove channels from the cut surface toward the center. The surface of the upper groove channel is coated with a gold film, and the surface of the lower groove channel is coated with a gold film and a tantalum pentoxide film. An analyte layer is filled between the upper and lower sides of the fiber core and the perfectly matched layer.
2. The dual-parameter photonic crystal fiber sensor based on surface plasmon resonance according to claim 1, characterized in that: The material of the fiber core is fused silica with a refractive index n=1.
45.
3. The dual-parameter photonic crystal fiber sensor based on surface plasmon resonance according to claim 2, characterized in that: The radius of the perfectly matched layer is r pml =6um; the radius of the fiber core is r0=5.5um.
4. The dual-parameter photonic crystal fiber sensor based on surface plasmon resonance according to claim 3, characterized in that: The circular air holes include 16 large circular air holes and 4 small circular air holes, and the circular air holes are symmetrically distributed in the fiber core; the period between the large circular air holes is Λ=2um, the period between the small circular air holes and the distance between the small circular air holes and the center of the fiber core is Λ s =1.75um.
5. The dual-parameter photonic crystal fiber sensor based on surface plasmon resonance according to claim 4, characterized in that: The large circular air holes are arranged in an array, and the air refractive index n of the large circular air holes is air =1, aperture size d = 1.55um; the small circular air hole is arranged parallel to the groove channel, and the air refractive index n of the small circular air hole air =1, aperture size d s =0.7um.
6. The dual-parameter photonic crystal fiber sensor based on surface plasmon resonance according to claim 5, characterized in that: The cut surface is divided into an upper side surface and a lower side surface, and the polishing depth of both surfaces is G=1 um.
7. The dual-parameter photonic crystal fiber sensor based on surface plasmon resonance according to claim 6, characterized in that: The depth of the two groove channels is H = 2.8um, and the width is d w =2.1um.
8. The dual-parameter photonic crystal fiber sensor based on surface plasmon resonance according to claim 7, characterized in that: The surface of the groove channel is coated with a gold film with a thickness t Au = 28nm, the thickness of the tantalum pentoxide film coated on the gold film layer in the lower groove channel is t Ta2o5 =10nm.
9. The dual-parameter photonic crystal fiber sensor based on surface plasmon resonance according to claim 8, characterized in that: The analyte layer is divided into a first analyte layer and a second analyte layer. The refractive index range of the solution to be tested in the first analyte layer is 1.38-1.4, and the temperature measurement range of the temperature-sensitive liquid in the second analyte layer is 20-40°C.
10. The dual-parameter photonic crystal fiber sensor based on surface plasmon resonance according to claim 9, characterized in that: The gold film layer and the tantalum pentoxide film layer generate surface plasmon resonance under the action of Y polarization.