A detection photonic crystal optical fiber and optical fiber sensor

Abstract

The present invention discloses a detection photonic crystal fiber and an optical fiber sensor, and relates to the field of optical fiber sensing technology. The detection photonic crystal fiber comprises: an optical fiber body, a sample channel, a coating and an air hole. The detection photonic crystal fiber comprises only one sample channel, an indium tin oxide film is coated on the inner surface of the sample channel, and a plurality of fiber cores are arranged around the sample channel. The plurality of fiber cores arranged around the sample channel can increase the influence of the incident light wave on the effective refractive index of the surface plasma mode and the core mode, so that the optical fiber sensor provided with the detection photonic crystal fiber can achieve 10 4 The wavelength sensitivity of the present invention is in the order of nm / RIU, and the optical fiber sensor of the present invention has the advantage of high sensitivity. The coating material selected by the present invention is indium tin oxide, which can reduce the production cost of the detection photonic crystal fiber and the optical fiber sensor.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber sensing technology, and in particular to a detection photonic crystal optical fiber and an optical fiber sensor. Background Art

[0002] High precision, ultra-sensitivity, and ultra-wideband are the main directions of the development of fiber optic sensing technology, which are of great significance in promoting scientific research and promoting social and economic development. Photonic crystal fiber sensing technology based on surface plasmon resonance is a new and advanced detection technology that has emerged internationally in recent years. It has the advantages of anti-electromagnetic interference, corrosion resistance, high sensitivity, electrical insulation, small size, light weight, small impact on the measured material, variable shape, wide range of measurement objects, easy networking, and can be used for remote measurement. It is widely used in many fields such as safe production, biomedicine, drug screening, food safety, aerospace, environmental testing, and national defense science and technology. The working principle of photonic crystal fiber sensing technology based on surface plasmon resonance is that the evanescent wave formed when the incident light is totally reflected internally at the interface between the photonic crystal fiber and the metal will induce the coherent oscillation of the free electrons on the metal surface, thereby generating surface plasma waves. When the evanescent wave resonates with the surface plasmon wave, energy is transferred from the photon to the surface plasmon, so that the plasma wave can absorb most of the energy of the incident light, causing the detected transmitted light intensity to be greatly weakened, forming a minimum peak value. Finally, the purpose of detecting the properties of unknown substances is achieved by measuring the resonant wavelength or the position of the loss peak of the analyte to be tested.

[0003] At present, the main problem of non-polarization-maintaining refractive index-guided photonic crystal fiber sensors based on surface plasmon resonance is that their sensitivity is not high enough. Their wavelength sensitivity is only 10 3 The insufficiency of nm / RIU level. Therefore, the existing optical fiber sensors have the problem of low sensitivity. Summary of the invention

[0004] The purpose of the present invention is to provide a detection photonic crystal fiber and an optical fiber sensor, which solves the problem of low sensitivity of the optical fiber sensor.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A detection photonic crystal optical fiber, comprising: an optical fiber body, a sample channel, a coating and an air hole;

[0007] The sample channel is arranged inside the optical fiber body, the sample channel is coaxially arranged with the optical fiber body and the sample channel is located at the center of the optical fiber body; the sample channel is used to place the liquid to be tested;

[0008] The coating is closely attached to the inner surface of the sample channel, and the coating is used to generate surface plasma waves;

[0009] The air hole is arranged inside the optical fiber body, the number of the air holes is multiple, and the central axes of the multiple air holes are parallel to the central axis of the optical fiber body;

[0010] The plurality of air holes are arranged around the sample channel in a regular hexagon;

[0011] The plurality of air holes are arranged into four layers of regular hexagons, the first layer of regular hexagons are arranged around the sample channel with the sample channel as the center, the second layer of regular hexagons are arranged outside the first layer of regular hexagons, the third layer of regular hexagons are arranged outside the second layer of regular hexagons, and the fourth layer of regular hexagons are arranged outside the third layer of regular hexagons;

[0012] The liquid to be tested is filled in a preset number of the air holes of the second regular hexagonal layer, and the preset number of the air holes filled with the liquid to be tested are symmetrically arranged, and the radius of the preset number of the air holes filled with the liquid to be tested is smaller than the radius of the air holes not filled with the liquid to be tested.

[0013] Optionally, the substrate material of the optical fiber body is pure quartz.

[0014] Optionally, the cross-section of the sample channel is circular, and the radius of the sample channel is 1 micron.

[0015] Optionally, the coating material is indium tin oxide;

[0016] The thickness of the coating is 40 nanometers to 60 nanometers.

[0017] Optionally, the cross-section of the air hole is circular, and the radius of the air hole is 0.5 microns.

[0018] Optionally, the radius of the preset number of air holes filled with the liquid to be tested is 0.05 microns-0.45 microns, and the preset number is four.

[0019] Optionally, the cross-section of the optical fiber body is circular, and the radius of the optical fiber body is 9.5 microns-11 microns.

[0020] An optical fiber sensor comprises: a light source, a polarizer, a coupling optical lens, a spectrum analyzer and the above-mentioned detection photonic crystal optical fiber;

[0021] The light source is used to provide a continuous incident light wave with a stable output;

[0022] The polarizer is located on the first outgoing light path of the light source; the polarizer is used to adjust the polarization state of the incident light wave;

[0023] The coupling optical lens is located on the second outgoing light path of the polarizer; the coupling optical lens is used to couple the second outgoing light path to the detection photonic crystal fiber;

[0024] The detection photonic crystal fiber is located at the focus of the coupling optical lens; the detection photonic crystal fiber is used to place the sample to be tested;

[0025] The spectrum analyzer is connected to the output end of the detection photonic crystal optical fiber; the spectrum analyzer is used to analyze the absorption peak of the transmission light wave incident into the spectrum analyzer.

[0026] Optionally, the wavelength range of the continuous incident light wave is 1300 nanometers to 3500 nanometers.

[0027] According to the specific embodiment provided by the present invention, the present invention discloses the following technical effects: The present invention discloses a detection photonic crystal fiber and a fiber sensor, including: a fiber body, a sample channel, a coating and an air hole. The detection photonic crystal fiber includes only one sample channel, an indium tin oxide film is coated on the inner surface of the sample channel, and the air hole filled with the liquid to be tested around the sample channel is the fiber core. The multiple fiber cores arranged around the sample channel can increase the influence of the incident light wave on the effective refractive index of the surface plasma mode and the core mode, so that the fiber sensor provided with the detection photonic crystal fiber can achieve 10 4 The wavelength sensitivity of the present invention is in the order of nm / RIU, and the optical fiber sensor of the present invention has the advantage of high sensitivity. The coating material selected by the present invention is indium tin oxide, which can reduce the production cost of the detection photonic crystal fiber and the optical fiber sensor; the optical fiber sensor can also simultaneously realize the sensing of the near-mid-infrared and mid-infrared bands (1400nm-2800nm), further expanding the application range of the optical fiber sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. 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 creative labor.

[0029] Figure 1 A cross-sectional view of the detection photonic crystal fiber provided in Example 1 of the present invention;

[0030] Figure 2 This is a structural diagram of the optical fiber sensor provided in Example 2 of the present invention.

[0031] Among them, 1. optical fiber body; 2. sample channel; 3. coating; 4. air hole; 5. first fiber core; 6. second fiber core; 7. third fiber core; 8. fourth fiber core; 9. light source; 10. polarizer; 11. coupling optical lens; 12. detection photonic crystal fiber; 13. spectrum analyzer. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Example 1

[0035] This embodiment 1 provides a detection photonic crystal fiber, Figure 1 This is a cross-sectional view of the detection photonic crystal fiber provided in Example 1 of the present invention. Figure 1 The detection photonic crystal fiber includes: a fiber body 1, a sample channel 2, a coating 3 and an air hole 4.

[0036] The substrate material of the optical fiber body 1 is pure quartz. The cross section of the optical fiber body 1 is circular, and the radius of the optical fiber body 1 is 9.5 microns to 11 microns.

[0037] The sample channel 2 is arranged inside the optical fiber body 1, the sample channel 2 is arranged coaxially with the optical fiber body 1 and the sample channel 2 is located at the center of the optical fiber body 1; the cross section of the sample channel 2 is circular, and the radius of the sample channel 2 is 1 micron. The sample channel 2 is used to place the liquid to be tested.

[0038] The coating 3 is closely attached to the inner surface of the sample channel 2. The material of the coating 3 is indium tin oxide. The thickness of the coating 3 is 40 nanometers to 60 nanometers. A layer of indium tin oxide with a thickness of 40 to 60 nanometers is coated on the inner surface of the sample channel 2, which can be used to generate surface plasma waves.

[0039] The air hole 4 is arranged inside the optical fiber body 1, and there are multiple air holes 4. The central axes of the multiple air holes 4 are parallel to the central axis of the optical fiber body 1. The cross section of the air hole 4 is circular, and the radius of the air hole 4 is 0.5 microns.

[0040] A plurality of air holes 4 are arranged around the sample channel 2 in a regular hexagonal shape.

[0041] The plurality of air holes 4 are arranged in four layers of regular hexagons, the first layer of regular hexagons are arranged around the sample channel 2 with the sample channel 2 as the center, the second layer of regular hexagons are arranged outside the first layer of regular hexagons, the third layer of regular hexagons are arranged outside the second layer of regular hexagons, and the fourth layer of regular hexagons are arranged outside the third layer of regular hexagons. The center spacing between any two adjacent air holes 4 in the plurality of air holes 4 is 1.8 microns to 2.2 microns. The distance between the first layer of regular hexagons and the second layer of regular hexagons is equal to the distance between the second layer of regular hexagons and the third layer of regular hexagons, and the distance is equal to the distance between the third layer of regular hexagons and the fourth layer of regular hexagons, and the distance is 1.56 microns to 1.91 microns.

[0042] The liquid to be tested is filled in a preset number of air holes 4 of the second regular hexagon, and the preset number of air holes 4 filled with the liquid to be tested are symmetrically arranged, the radius of the preset number of air holes 4 filled with the liquid to be tested is smaller than the radius of the air holes 4 not filled with the liquid to be tested, and the radius of the preset number of air holes 4 filled with the liquid to be tested is 0.05 microns-0.45 microns.

[0043] In this embodiment 1, the preset number is four, that is, the preset number of air holes filled with the liquid to be tested is four, and the four air holes filled with the liquid to be tested serve as the four cores of the detection photonic crystal fiber. In this embodiment 1, the four cores are respectively located above, below, left and right of the sample channel, that is, the first core 5 is located above the sample channel, the second core 6 is located below the sample channel, the third core 7 is located on the left of the sample channel, and the fourth core 8 is located on the right of the sample channel.

[0044] In the detection photonic crystal fiber of this embodiment 1, the four cores are located in the second layer of regular hexagons, which can enhance the coupling effect between the surface plasma mode and the core fundamental mode; the selected coating metal is indium tin oxide, which can reduce the production cost of the detection photonic crystal fiber.

[0045] Example 2

[0046] This embodiment 2 provides an optical fiber sensor, Figure 2 This is a structural diagram of the optical fiber sensor provided by Example 2 of the present invention. Figure 2 The optical fiber sensor comprises: a light source 9, a polarizer 10, a coupling optical lens 11, a spectrum analyzer 13 and the detection photonic crystal fiber 12 of embodiment 1.

[0047] The light source 9 is used to provide a continuous incident light wave with a stable output. The wavelength range of the continuous incident light wave is 1300 nanometers to 3500 nanometers. The light source 9 is preferably the Electro MIR supercontinuum light source of Sino Optics.

[0048] The polarizer 10 is located on the first outgoing light path of the light source 9; the polarizer 10 is used to adjust the polarization state of the incident light wave.

[0049] The coupling optical lens 11 is located on the second outgoing light path of the polarizer 10 ; the coupling optical lens 11 is used to couple the second outgoing light path to the detection photonic crystal fiber 12 .

[0050] The detection photonic crystal fiber 12 is located at the focus of the coupling optical lens 11; the detection photonic crystal fiber 12 is used to place the sample to be tested.

[0051] The spectrum analyzer 13 is connected to the output end of the detection photonic crystal fiber 12 ; the spectrum analyzer 13 is used to analyze the absorption peak of the transmitted light wave incident into the spectrum analyzer 13 , and to monitor the real-time changes of the surface plasmon resonance signal in the detection photonic crystal fiber 12 .

[0052] The optical fiber sensor also includes: an optical fiber clamp ( Figure 2 Not shown), three-dimensional optical fiber adjustment frame ( Figure 2 Not shown) and the optical platform ( Figure 2 not shown).

[0053] The light source 9, the polarizer 10, the coupling optical lens 11, the spectrum analyzer 13 and the three-dimensional optical fiber adjustment frame are all fixed on the optical platform, and the optical platform is used to fix the optical fiber sensor.

[0054] The detection photonic crystal fiber 12 is put into the fiber clamp and pressed, and the fiber clamp clamping the detection photonic crystal fiber 12 is fixed on the three-dimensional fiber adjustment frame. The three-dimensional fiber adjustment frame is used to fix the detection photonic crystal fiber 12 and adjust the position of the detection photonic crystal fiber 12 in three-dimensional space.

[0055] The working process of the optical fiber sensor of this embodiment 2 is as follows: the liquid to be tested is injected into the four cores and sample channel of the detection photonic crystal fiber by using the capillary phenomenon of the liquid, so that the detection photonic crystal fiber is coaxial with the coupling optical lens. The polarizer adjusts the incident light to x-polarized light, and makes the central axis of the first core of the detection photonic crystal fiber parallel to the polarization direction of the incident light. The first core of the detection photonic crystal fiber is located at the focus of the coupling optical lens, and the coupling optical lens efficiently couples the incident light into the core of the detection photonic crystal fiber, and the spectrum analyzer at the output end of the detection photonic crystal fiber performs real-time monitoring.

[0056] The working principle of the optical fiber sensor of the present embodiment 2 is as follows: when the refractive index of the liquid to be measured in the sample channel decreases, the effective refractive index of the surface plasmon mode and the core fundamental mode of the four fiber cores will also decrease as the refractive index of the liquid to be measured decreases, but the reduction amplitude of the surface plasmon mode is greater than that of the core fundamental mode, and the coupled resonance wavelength moves toward the short wavelength direction, thereby causing the absorption peak of the transmitted light wave input into the spectrometer to blue shift. Conversely, when the refractive index of the sample to be measured increases, since the increase amplitude of the effective refractive index of the surface plasmon mode is greater than that of the core fundamental mode, the coupled resonance wavelength moves toward the long wavelength direction, thereby causing the transmission absorption peak in the spectrometer to red shift. Therefore, the optical fiber sensor based on the detection photonic crystal fiber provided by the present invention can monitor the change of the refractive index of the sample to be measured in real time online.

[0057] The optical fiber sensor of the second embodiment can simultaneously realize sensing in the near-mid-infrared and mid-infrared bands (1400nm-2800nm), thus expanding the application scope of the optical fiber sensor.

[0058] The structure of the four cores and the indium tin oxide-plated sample channel used in the detection photonic crystal fiber of the present invention can enhance the influence of the incident light wave on the effective refractive index of the surface plasma mode and the core mode, thereby the optical fiber sensor can achieve 10 4 Wavelength sensitivity is measured in refractive index per unit nanometer (nm / RIU).

[0059] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0060] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A detection photonic crystal fiber, characterized in that: include: Fiber body, sample channel, coating and air holes; The sample channel is arranged inside the optical fiber body, the sample channel is coaxially arranged with the optical fiber body and the sample channel is located at the center of the optical fiber body; the sample channel is used to place the liquid to be tested; The coating is closely attached to the inner surface of the sample channel, and the coating is used to generate surface plasma waves; The air hole is arranged inside the optical fiber body, the number of the air holes is multiple, and the central axes of the multiple air holes are parallel to the central axis of the optical fiber body; The plurality of air holes are arranged around the sample channel in a regular hexagon; The plurality of air holes are arranged into four layers of regular hexagons, the first layer of regular hexagons are arranged around the sample channel with the sample channel as the center, the second layer of regular hexagons are arranged outside the first layer of regular hexagons, the third layer of regular hexagons are arranged outside the second layer of regular hexagons, and the fourth layer of regular hexagons are arranged outside the third layer of regular hexagons; The liquid to be tested is filled in a preset number of the air holes in the second regular hexagonal layer, and the preset number of the air holes filled with the liquid to be tested are symmetrically arranged, the radius of the preset number of the air holes filled with the liquid to be tested is smaller than the radius of the air holes not filled with the liquid to be tested, and the air holes filled with the liquid to be tested serve as the core of the detection photonic crystal fiber.

2. The detection photonic crystal fiber according to claim 1, characterized in that: The substrate material of the optical fiber body is pure quartz.

3. The detection photonic crystal fiber according to claim 1, characterized in that: The cross section of the sample channel is circular, and the radius of the sample channel is 1 micron.

4. The detection photonic crystal fiber according to claim 1, characterized in that: The coating material is indium tin oxide; The thickness of the coating is 40 nanometers to 60 nanometers.

5. The detection photonic crystal fiber according to claim 1, characterized in that: The cross section of the air hole is circular, and the radius of the air hole is 0.5 micrometers.

6. The detection photonic crystal fiber according to claim 1, characterized in that: The radius of the preset number of air holes filled with the liquid to be tested is 0.05 micrometers to 0.45 micrometers, and the preset number is four.

7. The detection photonic crystal fiber according to claim 1, characterized in that: The cross section of the optical fiber body is circular, and the radius of the optical fiber body is 9.5 microns to 11 microns.

8. An optical fiber sensor, characterized in that: include: A light source, a polarizer, a coupling optical lens, a spectrum analyzer and a detection photonic crystal fiber as claimed in any one of claims 1 to 7; The light source is used to provide a continuous incident light wave with a stable output; The polarizer is located on the first outgoing light path of the light source; the polarizer is used to adjust the polarization state of the incident light wave; The coupling optical lens is located on the second outgoing light path of the polarizer; the coupling optical lens is used to couple the second outgoing light path to the detection photonic crystal fiber; The detection photonic crystal fiber core is located at the focus of the coupling optical lens; the detection photonic crystal fiber is used to place the sample to be tested; The spectrum analyzer is connected to the output end of the detection photonic crystal optical fiber; the spectrum analyzer is used to analyze the absorption peak of the transmission light wave incident into the spectrum analyzer.

9. The optical fiber sensor according to claim 8, characterized in that: The wavelength range of the continuous incident light wave is 1300 nanometers to 3500 nanometers.

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