Double-ellipse macroporous PCF-SPR sensor capable of simultaneously measuring temperature and magnetic field

Abstract

The utility model belongs to the technical field of optical fiber sensing application, and particularly relates to a double-ellipse macroporous PCF-SPR sensor capable of simultaneously measuring temperature and a magnetic field. The sensor is a photonic crystal fiber, a regular hexagon area is defined by large air holes in a cladding of the fiber, a fiber core is a rectangular area with long sides parallel to the y axis, first small air holes are formed in the four vertexes of the rectangle respectively, and a second small air hole is formed in the center of the rectangular area. Two sides of a long edge of the rectangle are provided with symmetrically arranged large elliptical air holes, inner walls of the large air holes on two sides of a short edge of the rectangle are plated with gold films, and the two large air holes plated with the gold films are respectively filled with magnetic fluid and polydimethylsiloxane, so that simultaneous measurement of a magnetic field and a temperature is realized by the two substances. The photonic crystal fiber sensor has higher detection precision and small loss, the transmission efficiency is improved, the cross sensitivity problem caused by the temperature change of the sensor is very small, and the influence of the temperature change on the change of a magnetic field loss peak is also very small.

Description

Technical Field

[0001] This utility model belongs to the field of fiber optic sensing application technology, specifically relating to a double elliptical macroaperture PCF-SPR sensor that can simultaneously measure temperature and magnetic field. Background Technology

[0002] Fiber optic sensors are widely used in many fields, such as building monitoring, aerospace, oil and gas, medical, and intelligent transportation, due to their advantages of high sensitivity, resistance to electromagnetic interference, miniaturization, and lightweight design. Photonic crystal fibers, in particular, possess unique structural advantages unmatched by traditional fibers. They exhibit many superior characteristics, such as highly controllable mode area and dispersion, a wide single-mode transmission range, high birefringence, and good nonlinearity. This forms the foundation for the research and development of photonic crystal fiber devices, effectively expanding and increasing the application areas of optical fibers, giving them broad application prospects. With the development of technology, "integration" has become a direction for innovation in various fields. For example, in the electronics field, various integrated circuits have greatly improved product performance through integration methods. In the field of fiber optic sensing, the design of multi-parameter fiber optic sensors is currently a research direction.

[0003] The refractive index of the core of a photonic crystal fiber can be flexibly designed and controlled. The principle of SPR (Surface Plasmon Resonance) is that there is an electrically neutral ionized gas on the metal surface, also called ionized plasma, or plasma (later renamed plasmamon), which represents a phenomenon of collective oscillation of free electrons within a metal, called "plasmon". A photon is a boson, and a boson is a general term for particles that only have mass when they are in motion. The microscopic explanation of the SPR effect is as follows: When light enters the optically less dense medium (fiber core) from the optically denser medium (gold), total internal reflection occurs when the angle is greater than the critical angle. At this time, an evanescent wave enters the gold layer. Initially, photons collide with free electrons, achieving the first coupling. This causes the free electrons in the metal to become polarized. After polarization, an electric field perpendicular to the surface direction is generated on the inner surface of the gold film. Under the action of Coulomb force, the polarized electrons move back along the direction perpendicular to the gold film surface. This cycle continues, forming a collective oscillating motion of free electrons in the gold film, generating electromagnetic waves propagating along the direction of the metal surface, i.e., SPP waves. When the SPP waves and evanescent waves reach the resonance condition, the second coupling, i.e., resonant coupling, i.e., the SPR phenomenon, is achieved, forming SPW waves.

[0004] From a macroscopic perspective, the SPR phenomenon can be explained as follows: The metal surface has uniform free electrons, which are neutral. When a transient wave enters the metal, it causes the charge distribution within the metal to become uneven, thereby generating an electric field. Due to the principle of electromagnetic induction, the changing electric field will generate a changing magnetic field, thus generating an electromagnetic wave. This electromagnetic wave propagates within the metal film, i.e., the SPP wave. When it matches the phase of the transient wave, the surface plasmon resonance phenomenon (SPR phenomenon) is generated.

[0005] Existing fiber optic sensors cannot measure temperature and magnetic field simultaneously, resulting in low detection efficiency. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a double-elliptical macroaperture photonic crystal fiber sensor for simultaneous temperature and magnetic field measurement, thereby improving the performance of fiber optic sensors. This sensor can simultaneously measure magnetic and electric fields and exhibits high sensitivity. The double-elliptical macroaperture provides stronger light confinement, better limiting light to the central portion of the fiber core. This results in a sharper resonance peak in the loss spectrum of the fiber optic sensor, improving its detection accuracy. Simultaneously, this sensor has lower loss compared to other sensors, increasing its transmission efficiency, and the crosstalk of the magnetic field loss peak caused by temperature changes is also less.

[0007] The technical solution adopted in this utility model is as follows: a double-elliptical macroaperture PCF-SPR sensor (PCF-SPR is an abbreviation for surface plasmon resonance in photonic crystal fiber) that can simultaneously measure temperature and magnetic field. The double-elliptical macroaperture PCF-SPR sensor is a photonic crystal fiber. The cladding of the fiber is surrounded by a regular hexagonal region with large air holes. Its core is a rectangular region with its long side parallel to the y-axis. A first small air hole is provided at each of the four vertices of the rectangle, and a second small air hole is provided at the center of the rectangular region. Large elliptical air holes are symmetrically arranged on both sides of the long side of the rectangle. The inner walls of the large air holes on both sides of the short side of the rectangle are coated with a gold film, and the two large air holes coated with gold film are filled with magnetorheological fluid (FM) and polydimethylsiloxane (PDMS), respectively. These two substances enable the simultaneous measurement of magnetic field and temperature.

[0008] Furthermore, among the large air holes arranged in a regular hexagonal pattern, the outermost layer has 18 large air holes, and symmetrical large air holes are arranged on both sides of the two large air holes coated with gold film. The geometric centers of the large air holes are arranged in a triangular lattice.

[0009] Furthermore, the photonic crystal fiber has a diameter of 30µm, the large air hole has a diameter of 1.6µm, and the distance between the geometric centers of the large air holes arranged in a triangular lattice is 2µm; the diameters of the first and second small air holes are both 0.4µm; the minor axis of the large elliptical air hole is 1.4µm, and the major axis is 2.42µm; the thickness of the gold film is 45nm.

[0010] Furthermore, the geometric centers of the large air holes in the inner and outer periphery of the fiber core, the small air holes at the four corners and center of the rectangular region in the core center, the two large elliptical air holes in the central part of the fiber core, the large air holes filled with MF, and the large air holes filled with PMDS are all arranged in a triangular lattice structure.

[0011] Furthermore, the rectangular area at the center of the fiber core of the fiber sensor serves as the light guiding area. The four corners and the center of the rectangular area are small air holes of the same size. Gold films are deposited in the large circular air holes on both sides of the short side of the rectangular area and filled with polydimethylsiloxane and magnetic fluid, respectively. Two large elliptical air holes of the same size are set on both sides of the long side of the rectangular area.

[0012] Furthermore, the PCF sensor, capable of simultaneously measuring temperature and magnetic field, significantly improves detection efficiency and reduces material costs compared to existing single-parameter sensors. Simultaneously, it enhances sensitivity compared to existing temperature and magnetic field sensors, and its loss spectrum peak sharpness is higher than that of existing fiber optic sensors. This results in higher detection accuracy for the photonic crystal fiber sensor, with low loss, greatly improving transmission efficiency. Additionally, the cross-sensitivity problem caused by temperature changes is minimal, and the impact of temperature changes on the magnetic field loss peak is also small.

[0013] The beneficial effects of this invention are as follows: It provides a double-elliptical macro-aperture PCF-SPR sensor that can simultaneously measure temperature and magnetic field. Compared with existing technologies, it can simultaneously measure temperature and magnetic field, exhibiting high sensitivity and low crosstalk. Its main advantages are as follows:

[0014] (1) The photonic crystal fiber sensor has a gold film plated inside the air hole in the center part of the core, which can better couple with the light guiding area of ​​the core and is conducive to exciting the SPR effect.

[0015] (2) Temperature and magnetic field can be measured simultaneously by filling the air holes of the gold-plated film with MF and PDMS respectively.

[0016] (3) The crosstalk between the magnetic field and temperature sensitivity of the sensor is small, and the temperature change has little effect on the magnetic field loss spectrum.

[0017] (4) The sensor has high sensitivity. The highest temperature sensitivity between 20 ℃ and 32 ℃ is 4.025 nm / ℃, and the highest magnetic field sensitivity between 32 Oe and 64 Oe is 2.042 nm / Oe. Attached Figure Description

[0018] Figure 1 This is a cross-sectional schematic diagram of a double-elliptical macroaperture PCF-SPR sensor.

[0019] Figure 2 This is a schematic diagram of the three-dimensional structure of a double elliptical macroaperture PCF-SPR sensor.

[0020] Figure 3 This is a schematic diagram of the effective refractive index and loss spectrum of the y-polarization core mode and polarization mode of the double elliptical macroaperture PCF-SPR sensor.

[0021] Figure 4 This is a loss curve of the base film y-polarization of a double elliptical macroaperture PCF-SPR sensor at an ambient temperature of 25℃.

[0022] Figure 5 This is a loss curve of the base film y-polarization of a double elliptical macroaperture PCF-SPR sensor when the ambient magnetic field strength is 32H. Detailed Implementation Example

[0023] like Figure 1 and Figure 2 As shown, a dual-elliptical macroaperture PCF-SPR sensor capable of simultaneously measuring temperature and magnetic field is disclosed. The dual-elliptical macroaperture PCF-SPR sensor is a photonic crystal fiber 9. The cladding of the fiber is surrounded by a regular hexagonal region enclosed by large air holes 2. Its core is a rectangular region with its long side parallel to the y-axis. A first small air hole 3 is provided at each of the four vertices of the rectangle, and a second small air hole 5 is provided at the center of the rectangular region. Large elliptical air holes 4 are symmetrically arranged on both sides of the long side of the rectangle. A gold film 8 is deposited on the inner wall of the large air holes 2 on both sides of the short side of the rectangle, and the two large air holes 2 with the gold film 8 are filled with a magnetorheological fluid 1 and polydimethylsiloxane 7, respectively.

[0024] In the large hexagonal air holes 2, there are 18 large air holes 2 in the outermost layer. Symmetrical large air holes 2 are arranged on both sides of the two large air holes 2 coated with gold film. The geometric centers of the large air holes 2 are arranged in a triangular lattice 6. The diameter of the photonic crystal fiber is 30µm and the core diameter is 14µm; the diameter of the large air holes 2 is 1.6µm, and the spacing between the geometric centers of the large air holes 2 arranged in a triangular lattice 6 is 2µm; the diameter of the first small air hole 3 and the second small air hole 5 is 0.4µm; the minor axis of the large elliptical air hole 4 is 1.4µm and the major axis is 2.42µm; the thickness of the gold film 8 is 45nm. Example

[0025] By depositing a gold film inside the air hole of an optical fiber and filling it with MF and PDMS, the SPR effect is generated, enabling simultaneous measurement of ambient magnetic field and temperature. One end of a double-elliptical macroaperture PCF-SPR sensor is connected to a broadband laser source with a continuously varying spectral range of 500–2500 nm, and the other end is connected to a spectrometer. The broadband laser source is turned on, and the wavelength is set from 680 nm to 1000 nm to excite the SPR effect within this wavelength range. The loss spectrum of the double-elliptical macroaperture PCF-SPR sensor is obtained when the ambient temperature is 25°C and the magnetic field strength varies between 32H and 64H. Figure 3 As shown. The broadband laser source was turned on, and the wavelength of the source was set from 680nm to 1000nm. The SPR effect was excited in this wavelength range, and the loss spectrum of the double elliptical macroaperture PCF-SPR sensor was obtained when the ambient magnetic field strength was 32H and the temperature varied between 20 ℃ and 32 ℃.

[0026] Because the gold film 8 of the double-elliptical macroaperture photonic crystal fiber is located in the fiber core, light transmitted in the fiber core can couple more fully with the gold film, thereby improving sensing sensitivity. Since the double-elliptical macroaperture photonic crystal fiber sensor fills the two air holes with MF and PDMS respectively, the sensor can simultaneously measure magnetic fields and temperature.

[0027] The magnetic field sensitivity of photonic crystal fiber dual-parameter temperature and magnetic field sensors is generally low. Compared with existing technologies, this sensor improves the magnetic field sensitivity by nearly an order of magnitude. Due to the dual influence of temperature and magnetic field on magnetic nanoparticles, temperature-induced cross-sensitivity issues arise. This sensor solves this problem. Figure 4 As shown, when the magnetic field changes, SPR peak 3, associated with magnetic field measurement, shifts significantly, while SPR peak 2, associated with temperature measurement, does not shift significantly; as Figure 5 As shown, when the ambient temperature changes, the SPR peak 2 associated with temperature measurement shifts significantly, while the SPR peak 3 associated with magnetic field measurement does not shift significantly, indicating that the crosstalk between temperature and magnetic field sensing is small.

Claims

1. A double-elliptical macroaperture PCF-SPR sensor capable of simultaneously measuring temperature and magnetic field, characterized in that: The double-elliptical large-aperture PCF-SPR sensor is a photonic crystal fiber (9). The cladding of the fiber is surrounded by a regular hexagonal region with large air holes (2). Its core is a rectangular region with the long side parallel to the y-axis. The four vertices of the rectangle are provided with a first small air hole (3), and the center of the rectangular region is provided with a second small air hole (5). Large elliptical air holes (4) are symmetrically arranged on both sides of the long side of the rectangle. The inner walls of the large air holes (2) on both sides of the short side of the rectangle are coated with a gold film (8), and the two large air holes (2) coated with the gold film (8) are filled with a magnetic fluid (1) and polydimethylsiloxane (7), respectively.

2. The dual-elliptical macroaperture PCF-SPR sensor capable of simultaneously measuring temperature and magnetic field according to claim 1, characterized in that: In the large air holes (2) arranged in regular hexagons, there are 18 large air holes (2) in the outermost layer. The two large air holes (2) coated with gold film are arranged with symmetrical large air holes (2) on both sides. The geometric centers of the large air holes (2) are arranged in a triangular lattice (6).

3. The dual-elliptical macroaperture PCF-SPR sensor capable of simultaneously measuring temperature and magnetic field according to claim 1, characterized in that: The diameter of the photonic crystal fiber is 30µm, the diameter of the large air hole (2) is 1.6µm, and the distance between the geometric centers of the large air holes (2) arranged in a triangular lattice (6) is 2µm; the diameters of the first small air hole (3) and the second small air hole (5) are both 0.4µm; the minor axis of the large elliptical air hole (4) is 1.4µm and the major axis is 2.42µm; the thickness of the gold film (8) is 45nm.

Images