Photonic crystal fiber sensor

Abstract

The invention belongs to the technical field of optical fiber sensing, and particularly relates to a photonic crystal optical fiber sensor which is characterized in that a cladding material is silicon dioxide, a to-be-detected solution channel is formed in the cladding of an optical fiber, and a first inner-layer air hole and a second inner-layer air hole are formed outside the to-be-detected solution channel; the inner wall of the second inner layer air hole in the X-axis positive half axis direction is plated with a silver film, a plurality of outer layer air holes are formed in the outer portion of the second inner layer air hole, every two outer layer air holes form a group, and each group of air holes are evenly distributed in the circumferential direction. The aperture of the outer-layer air holes is larger than that of the first inner-layer air holes and that of the second inner-layer air holes; the number of the first inner layer air holes is 16, and the diameter of the first inner layer air holes is 1.5 mm; the number of the second inner layer air holes is 24, and the diameter of the second inner layer air holes is 1.5 mm. The number of the outer layer air holes is 16, and the diameter of the outer layer air holes is 2.5 mm. The diameter of the to-be-detected solution channel is 7.3 mm; and the thickness of the silver film is 40nm.

Description

Technical Field

[0001] The invention belongs to the technical field of optical fiber sensors, and in particular relates to a photonic crystal optical fiber sensor. Background Art

[0002] The existing photonic crystal fiber sensor has a limited range of refractive index variation of the liquid to be measured, which limits the maximum sensitivity that can be measured. In addition, the sensitivity is not high, which affects the detection range and accuracy. Summary of the Invention

[0003] To address the above technical issues, the present invention provides a photonic crystal fiber sensor. This fiber sensor can measure liquids with a refractive index range of 1.29-1.39 and a maximum sensitivity of 24,600 nm / RIU. This sensor exhibits high sensitivity and is easy to promote and use.

[0004] The technical solution of the present invention is as follows: a photonic crystal fiber sensor, wherein the cladding material of the photonic crystal fiber sensor is silicon dioxide, a channel for a solution to be tested is provided in the middle of the optical fiber cladding of the photonic crystal fiber sensor, a first inner layer air hole and a second inner layer air hole are provided on the outside of the channel for the solution to be tested, wherein the inner wall of the second inner layer air hole in the positive semi-axis direction of the X-axis is plated with a silver film, a plurality of outer layer air holes are provided on the outside of the second inner layer air hole, the plurality of outer layer air holes are grouped in pairs, and the air holes in each group are evenly distributed on the circumference; the first inner layer air hole and the second inner layer air hole are provided on the outside of the second inner layer air hole, wherein ... first inner layer air hole and the second inner layer air hole are provided on the outside of the first inner layer air hole and the first inner layer air hole and the second inner layer air hole are provided on the outside of the first inner layer air hole and the first inner layer air hole and the second inner layer air hole are provided on the outside of the first inner layer air hole and the first inner layer air hole and the second inner layer air hole are provided on the outside of the first inner layer air hole and the first inner layer air hole and the second inner layer air hole The apertures of the air pores in the first and second inner layers are the same, and the apertures of the air pores in the outer layer are larger than those of the air pores in the first and second inner layers; the number of the air pores in the first inner layer is 12-20, and the diameter of the air pores in the first inner layer is 1.3-1.7 mm; the number of the air pores in the second inner layer is 20-28, and the diameter of the air pores in the second inner layer is 1.3-1.7 mm; the number of the air pores in the outer layer is 12-20, and the diameter of the air pores in the outer layer is 2.3-2.7 mm; the diameter of the solution channel to be tested is 6.8-7.8 mm; and the thickness of the silver film is 38 nm-52 nm.

[0005] Furthermore, the number of air holes in the first inner layer is 16.

[0006] Furthermore, the diameter of the air holes in the first inner layer is 1.5 mm.

[0007] Furthermore, the number of the second inner layer air holes is 24.

[0008] Furthermore, the diameter of the second inner layer air holes is 1.5 mm.

[0009] Furthermore, the number of the outer layer air holes is 16.

[0010] Furthermore, the diameter of the outer air holes is 2.5 mm.

[0011] Furthermore, the diameter of the test solution channel is 7.3 mm.

[0012] Furthermore, the thickness of the silver film is 40 nm.

[0013] The present invention provides a photonic crystal fiber sensor capable of measuring liquids with a refractive index range of 1.29-1.39 and a maximum sensitivity of 24,600 nm / RIU. The sensor exhibits high sensitivity and is easy to promote and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic cross-sectional view of a photonic crystal fiber sensor.

[0015] Figure 2 This is a graph showing the corresponding relationship between the sensor's resonant wavelength and the refractive index of different liquids.

[0016] Figure 3 The refractive index of different liquids in the sensor corresponds to HE 11 Mode loss spectrum. DETAILED DESCRIPTION

[0017] like Figure 1-3 As shown, a photonic crystal fiber sensor is provided. The cladding material of the photonic crystal fiber sensor is silicon dioxide. A test solution channel 11 is provided in the middle of the fiber cladding of the photonic crystal fiber sensor. A plurality of first inner layer air holes 12 and second inner layer air holes 13 are provided outside the test solution channel, wherein the inner wall of the second inner layer air holes in the positive semi-axis direction of the X-axis is plated with a silver film 15. A plurality of outer layer air holes 14 are provided outside the second inner layer air holes. The plurality of outer layer air holes form a group of two, and each group of air holes is evenly distributed around the circumference. The first inner layer air holes and the second inner layer air holes are provided outside the second inner layer air holes. The apertures of the inner layer air pores are the same, and the apertures of the outer layer air pores are larger than the apertures of the first inner layer air pores and the second inner layer air pores; the number of the first inner layer air pores is 12-20, and the diameter of the first inner layer air pores is 1.3-1.7 mm; the number of the second inner layer air pores is 20-28, and the diameter of the second inner layer air pores is 1.3-1.7 mm; the number of the outer layer air pores is 12-20, and the diameter of the outer layer air pores is 2.3-2.7 mm; the diameter of the test solution channel is 6.8-7.8 mm; and the thickness of the silver film is 38nm-52nm.

[0018] Preferably, the number of air holes in the first inner layer is 16, and the diameter of the first inner layer air holes is 1.5 mm. The number of air holes in the second inner layer is 24, and the diameter of the second inner layer air holes is 1.5 mm. The number of air holes in the outer layer is 16, and the diameter of the outer layer air holes is 2.5 mm. The diameter of the test solution channel is 7.3 mm. The thickness of the silver film is 40 nm.

[0019] The photonic crystal fiber can flexibly adjust the arrangement of air holes to make the measurement of the refractive index of the analyte more accurate. The air holes in the cladding of the photonic crystal fiber are arranged in a ring structure to form an SPR sensor. 11 The mode excites surface plasmon resonance, making it more sensitive and stable.

[0020] The OAM laser light source generates a vortex beam with orbital angular momentum, which is totally reflected within the photonic crystal fiber. When the propagation constants of the evanescent wave and the surface plasmon resonance wave are equal, surface plasmon resonance occurs. A loss curve is displayed on the spectrometer, and the data from this loss curve is transmitted to a computer for processing and analysis. SPR is very sensitive to changes in the refractive index of the surrounding environment. The relationship between the refractive index of crude oil with different water contents and the resonance wavelength corresponding to its loss peak is observed by observing the spectrum.

[0021] The photonic crystal fiber sensor's cladding contains two layers of small air holes and one layer of large air holes, with a channel for the solution to be measured in between. Crude oil with varying water contents is injected into the channel under pressure. A silver film is applied to the second inner layer of air holes, horizontal to the positive x-axis. The large and small air holes are arranged in a ring structure, and their refractive index is determined by the Sellmeier equation.

[0022] The sensing model of this detection system is established by simulation software, and its sensing process is simulated to obtain a complex form of HE 11 The effective refractive index of the mode. The transmission loss can be calculated by its imaginary part:

[0023] Where λ represents the wavelength of incident light in nm, n eff Represents HE 11 The effective refractive index of the mode is obtained through this formula. The energy loss changes with wavelength under the refractive index of crude oil with different water content. Some loss curves are as follows Figure 3 As shown in the figure, when the refractive index of the liquid to be tested changes in the range of 1.29-1.39, the resonance peaks all red-shift as the refractive index of the liquid to be tested increases.

[0024] The average spectral sensitivity can be calculated as follows:

[0025] Where Δλ represents the change in the resonance wavelength, and Δn represents the change in the refractive index of the liquid to be measured. Figure 2 It can be seen that the average sensitivity is 22430 nm / RIU and the maximum sensitivity is 24600 nm / RIU.

[0026] The refractive index of the liquid being measured by the fiber optic sensor varies from 1.29 to 1.39, and the maximum sensitivity can be measured is 24600nm / RIU. The measurement process is more stable and has higher sensitivity.

Claims

1. A photonic crystal fiber sensor, characterized in that: The cladding material of the photonic crystal fiber sensor is silicon dioxide. A channel for a solution to be tested is provided in the middle of the fiber cladding of the photonic crystal fiber sensor. A plurality of first inner layer air holes and second inner layer air holes are provided on the outside of the channel for the solution to be tested, wherein the inner wall of the second inner layer air hole in the positive semi-axis direction of the X-axis is plated with a silver film. A plurality of outer layer air holes are provided on the outside of the second inner layer air holes, and the plurality of outer layer air holes form a group of two, and each group of air holes is evenly distributed around the circumference; the apertures of the first inner layer air holes and the second inner layer air holes are the same, and the outer layer air holes are arranged on the outside of the second inner layer air holes. The pore diameter is larger than the pore diameter of the first inner layer air pore and the second inner layer air pore; the number of the first inner layer air pores is 12-20, and the diameter of the first inner layer air pores is 1.3-1.7 mm; the number of the second inner layer air pores is 20-28, and the diameter of the second inner layer air pores is 1.3-1.7 mm; the number of the outer layer air pores is 12-20, and the diameter of the outer layer air pores is 2.3-2.7 mm; the diameter of the test solution channel is 6.8-7.8 mm; the thickness of the silver film is 38nm-52nm.

2. The photonic crystal fiber sensor according to claim 1, wherein: The number of the air holes in the first inner layer is 16.

3. The photonic crystal fiber sensor according to claim 1, wherein: The diameter of the air holes in the first inner layer is 1.5 mm.

4. The photonic crystal fiber sensor according to claim 1, wherein: The number of the second inner layer air holes is 24.

5. The photonic crystal fiber sensor according to claim 1, wherein: The diameter of the air holes in the second inner layer is 1.5 mm.

6. The photonic crystal fiber sensor according to claim 1, wherein: The number of the outer layer air holes is 16.

7. The photonic crystal fiber sensor according to claim 1, wherein: The diameter of the outer layer air holes is 2.5 mm.

8. The photonic crystal fiber sensor according to claim 1, wherein: The diameter of the test solution channel is 7.3 mm.

9. The photonic crystal fiber sensor according to claim 1, wherein: The thickness of the silver film is 40 nm.

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