An ethanol-filled single-polarization temperature sensor based on a negative-curvature optical fiber

Abstract

The present invention discloses an ethanol-filled single-polarization temperature sensor with a negative-curvature optical fiber, including a cladding region and a core region; the cladding region includes 8 elliptical quartz tubes arranged uniformly, the major axis of the elliptical quartz glass tube is d1 and the minor axis is d2; the thickness of the elliptical quartz glass tube is t; the included angle between adjacent elliptical quartz glass tubes is 44.5 to 45.5 degrees; among them, the filling materials of 6 elliptical quartz glass tubes are ethanol, and the filling materials of 2 elliptical quartz glass tubes are gold; there are 3 elliptical quartz glass tubes filled with ethanol between the 2 elliptical quartz glass tubes filled with gold, and the centers of the 2 elliptical quartz glass tubes filled with gold and the center of the optical fiber are on the same straight line; the core region is the region surrounded by the 8 elliptical quartz glass tubes; the measurement range of this sensor is from 20°C to 70°C, and the sensitivity reaches 3.03 nm / °C. There is a good linear relationship between temperature and wavelength.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber sensors, and particularly to an ethanol-filled negative-curvature optical fiber single-polarization temperature sensor. Background Art

[0002] Optical fibers, as a new generation of transmission media, have been widely used in information transmission and sensing fields. Currently, optical fiber sensors have been used for sensing various physical quantities. For example, temperature, refractive index, pressure, etc. Among the above sensors, temperature sensors play an indispensable role in people's daily life and production. Currently, the main ways for people to use optical fibers for temperature sensing are as follows:

[0003] Based on traditional optical fibers, the traditional optical fibers are tapered or the cladding of the optical fibers is ground thin to make the core contact the external environment more fully. In this way, the external environment will strongly affect the transmission of modes in the core, and different temperatures have different effects on the transmission of optical fiber modes. Based on this, temperature sensing can be realized. However, in this case, the optical fiber will become extremely fragile and easily break.

[0004] Based on photonic crystal fibers, photonic crystal fibers are optical fibers with periodically arranged microstructured holes in the cladding. According to their light guiding principles, they can be divided into total internal reflection type photonic crystal fibers and photonic bandgap type photonic crystal fibers. For total internal reflection type photonic crystal fibers, due to the microstructured holes in the cladding, its core is formed by missing air holes, and the average refractive index of its cladding is lower than that of the core, enabling light to propagate in the core. The light guiding mechanism of photonic bandgap type photonic crystal fibers is the photonic bandgap effect. Its cladding contains densely and strictly arranged air holes, forming a photonic energy band effect. By introducing a defect state (usually a large air hole) in the center, some light in the photonic bandgap of the cladding can propagate in the central air hole. However, due to the extremely complex structure of photonic crystal fibers, which usually have hundreds or thousands of air holes and the diameter of the air holes is usually only a few micrometers, the processing of photonic crystal fibers is difficult and the success rate is very low.

[0005] Optical fiber gratings are formed by axially periodically modulating the refractive index of the core of an optical fiber by a certain method. The grating period and the effective refractive index of the grating region are affected by the external environment. Based on this principle, optical fiber gratings can also be used for temperature sensing. However, the temperature sensitivity of optical fiber gratings is generally very low. Summary of the Invention

[0006] Aiming at the above technical problems, the purpose of the present invention is to provide an ethanol-filled negative-curvature optical fiber single-polarization temperature sensor to at least solve one of the above-mentioned technical problems, specifically as follows.

[0007] An ethanol-filled negative-curvature fiber single-polarization temperature sensor, comprising: a cladding region and a core region; the cladding region includes 8 elliptical quartz tubes arranged uniformly, the major axis of the elliptical quartz glass tube is d1, and the minor axis is d2; the thickness of the elliptical quartz glass tube is t; the included angle between adjacent elliptical quartz glass tubes is 44.5 to 45.5 degrees; wherein, the filling material of 6 of the elliptical quartz glass tubes is ethanol, and the filling material of 2 of the elliptical quartz glass tubes is gold; there are 3 elliptical quartz glass tubes filled with ethanol between the 2 elliptical quartz glass tubes filled with gold, and the centers of the 2 elliptical quartz glass tubes filled with gold are on the same straight line as the center of the optical fiber; the core region is the region surrounded by the 8 elliptical quartz glass tubes. The linear fitting equation between the wavelength position y of the loss peak of the sensor and the corresponding temperature x satisfies the following relationship: y = 0.00303x + 1.52605.

[0008] Optionally, the goodness of fit R of the linear fitting equation 2 is 0.99889.

[0009] Optionally, the range of the major axis d1 of the elliptical quartz glass tube is: 34 μm to 36 μm.

[0010] Optionally, the range of the minor axis d2 of the elliptical quartz glass tube is: 20 μm to 22 μm.

[0011] Optionally, the range of the thickness t of the elliptical quartz glass tube is: 0.4 μm to 0.6 μm.

[0012] Optionally, the range of the thickness t of the elliptical quartz glass tube is: 0.4 μm to 0.6 μm.

[0013] Optionally, the included angle between adjacent elliptical quartz glass tubes is 45 degrees.

[0014] Optionally, the range of the radius R of the optical fiber is: 69 μm to 71 μm.

[0015] Optionally, the filling material of the core region is ethanol.

[0016] Compared with the prior art, the present invention has the following technical effects:

[0017] The present invention provides an ethanol-filled negative-curvature fiber single-polarization temperature sensor, including 8 elliptical quartz tubes arranged uniformly, and the included angle between adjacent elliptical quartz glass tubes is 44.5 to 45.5 degrees; the filling material of 6 of the elliptical quartz glass tubes is ethanol, and the filling material of 2 of the elliptical quartz glass tubes is gold. The measurement range of this sensor is from 20 °C to 70 °C, and the sensitivity reaches 3.03 nm / °C. There is a good linear relationship between temperature and wavelength, and the goodness of fit R 2It reached 0.99889. Only the x-polarization state of the core mode is used for sensing within the measured temperature range, avoiding the interference of the y-polarization state of the core mode on the sensing result in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0019] Figure 1 is a cross-sectional view of the ethanol-filled negative-curvature fiber single-polarization temperature sensor of the present invention.

[0020] Figure 2 is a graph showing the relationship between the effective refractive index and wavelength of the ethanol-filled negative-curvature fiber single-polarization temperature sensor of the present invention at 20°C.

[0021] Figure 3 is a graph showing the relationship between the loss and wavelength of the ethanol-filled negative-curvature fiber single-polarization temperature sensor of the present invention at 20°C.

[0022] Figure 4 is a graph showing the relationship between the loss and wavelength of the ethanol-filled negative-curvature fiber single-polarization temperature sensor of the present invention at 20°C - 70°C.

[0023] Figure 5 is a linear fitting graph of the wavelength position of the loss peak of the ethanol-filled negative-curvature fiber single-polarization temperature sensor of the present invention versus temperature.

[0024] Figure 1 Among them, 1 - 8 are 8 elliptical quartz glass tubes with a thickness of t, an internal major axis length of d1, and an internal minor axis length of d2. Among them, the interiors of elliptical quartz glass tubes 4 and 8 are filled with gold, and the interiors of 4 and 8 are completely filled with gold. The interiors of elliptical quartz glass tubes 1, 2, 3, 5, 6, 7 and the rest of the interior of the entire optical fiber ( Figure 1 in 9) are completely filled with ethanol. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the following will further describe the present invention in detail with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0026] like Figure 1 As shown, an ethanol-filled negative curvature optical fiber single polarization temperature sensor comprises: a cladding region and a core region; the cladding region comprises 8 uniformly arranged elliptical quartz tubes, the long axis of the elliptical quartz glass tubes being d1 and the short axis being d2; the thickness of the elliptical quartz glass tubes being t; the angle between adjacent elliptical quartz glass tubes being 44.5 to 45.5 degrees; wherein, 6 of the elliptical quartz glass tubes are filled with ethanol, and 2 of the elliptical quartz glass tubes are filled with gold; 3 elliptical quartz glass tubes filled with ethanol are spaced between the 2 elliptical quartz glass tubes filled with gold, and the centers of the 2 elliptical quartz glass tubes filled with gold are in a straight line with the center of the optical fiber; the core region is the region surrounded by the 8 elliptical quartz glass tubes.

[0027] Optionally, the range of the long axis d1 in the elliptical quartz glass tube is: 34μm to 36μm. The range of the short axis d2 in the elliptical quartz glass tube is: 20μm to 22μm. Taking values ​​for the elliptical quartz glass tube within this numerical range will make the sensor have a strong sensitivity and can accurately detect temperature changes, with a sensitivity of 3.03nm / ℃.

[0028] The thickness t of the oval quartz glass tube is in the range of 0.4 μm to 0.6 μm. If the oval quartz glass tube is selected within this numerical range, the sensor will have a strong sensitivity and can accurately detect temperature changes, with a sensitivity of 3.03 nm / °C.

[0029] The angle between adjacent oval quartz glass tubes is 45 degrees. If the oval quartz glass tube is selected within this numerical range, the sensor will have a strong sensitivity and can accurately detect temperature changes, with a sensitivity of 3.03nm / ℃.

[0030] The range of the optical fiber radius R is: 69μm to 71μm. Selecting the optical fiber radius within this numerical range can effectively receive the incident light and make its polarization base film propagate at the optical fiber core, which is beneficial to the detection of the temperature signal carried by the optical signal.

[0031] The present invention provides an ethanol-filled negative curvature optical fiber single polarization temperature sensor, comprising 8 evenly arranged elliptical quartz tubes, the angle between adjacent elliptical quartz glass tubes is 44.5-45.5 degrees; 6 of the elliptical quartz glass tubes are filled with ethanol, and 2 of the elliptical quartz glass tubes are filled with gold. The sensor has a measurement range of 20°C to 70°C, and a sensitivity of 3.03nm / °C. There is a good linear relationship between temperature and wavelength, and the fitting parameter R 2It reached 0.99889. In the measured temperature range, only the x-polarization state of the core mode is used for sensing, avoiding the interference of the y-polarization state of the core mode in practical applications on the sensing results.

[0032] As Figure 1 shown, 1 - 8 are 8 elliptical quartz glass tubes. Among them, the interiors of elliptical quartz glass tubes 4 and 8 are both filled with gold, such as gold wires, and the gold wires completely fill the interiors of 4 and 8. The interiors of elliptical quartz glass tubes 1, 2, 3, 5, 6, 7 and the rest 9 of the entire optical fiber interior are all completely filled with ethanol. The core region is the central region enclosed by elliptical quartz glass tubes 1 - 8. Since the refractive index of ethanol is lower than that of quartz within the measured range, the light guiding mechanism of the optical fiber is not total internal reflection. This temperature sensor also does not have a photonic bandgap structure, so it is not a light guiding mechanism of a photonic bandgap either. The light guiding mechanism of this temperature sensor is anti-resonance. The interiors of elliptical quartz glass tubes 4 and 8 are both filled with gold. When light enters the optical fiber, surface plasmon modes will be generated in 4 and 8 respectively. According to the coupled mode theory, mode coupling effects will occur between the surface plasmon modes in 4 and 8 respectively, thus forming a surface plasmon supermode. Also, because 4 and 8 are elliptical, the surface plasmon supermode formed by them has high birefringence characteristics. While the birefringence of the core mode is very small, so within the measured range, only the x-polarization state of the core mode and the surface plasmon supermode have an SPR effect.

[0033] Among them, SPR is surface plasmon resonance, a sensitive surface analysis technology, which is detected by the change of dielectric constant caused by molecules adsorbed on a heavy metal film.

[0034] Therefore, there are a total of 2 light guiding mechanisms in this optical fiber, namely the anti-resonance mechanism of the core fundamental mode and the light guiding mechanism of the surface plasmon supermode jointly formed by the surface plasmon modes in 4 and 8 respectively.

[0035] Figure 2 Taking the ethanol-filled negative curvature optical fiber single-polarization temperature sensor of the present invention at 20 °C as an example, it is a graph showing the relationship between the refractive indices of the x-polarization state and y-polarization state of the core fundamental mode and the surface plasmon supermode and the wavelength. From Figure 2 it can be seen that within the measured wavelength range, the effective refractive index of the y-polarization state mode does not have an SPR effect with the 0th-order surface plasmon supermode, while the effective refractive index of the x-polarization state mode and the 0th-order surface plasmon supermode have an SPR effect at a wavelength of 1.584 microns. The situation at other temperatures is the same as that at 20 °C in terms of mechanism, except that the wavelength at which the SPR effect occurs has changed.

[0036] Figure 3This is a graph showing the relationship between the losses of the x-polarized and y-polarized modes of the fundamental core mode of the ethanol-filled negative-curvature fiber single-polarization temperature sensor of the present invention at 20°C as a function of wavelength. From Figure 3 it can be seen that a loss peak appears at a wavelength of 1.584 μm for the x-polarized mode, while the loss of the y-polarized mode is very low. Figure 2 and Figure 3 form a corresponding relationship. The mechanism for other temperatures is the same as that at 20°C, except that the wavelength position of the loss peak changes.

[0037] Figure 4 This is the relationship between the loss and wavelength of the ethanol-filled negative-curvature fiber single-polarization temperature sensor of the present invention at 20°C - 70°C. As the temperature increases, the loss peak undergoes a red shift and the loss increases.

[0038] Figure 5 This is a linear fitting graph of the wavelength position of the loss peak of the ethanol-filled negative-curvature fiber single-polarization temperature sensor of the present invention as a function of temperature. Combining Figure 4 and Figure 5 form a corresponding relationship. From Figure 5 it can be seen that for this temperature sensor, the linear fitting equation for the wavelength position of the loss peak and the corresponding temperature is y = 0.00303x + 1.52605, where x represents the temperature and y represents the wavelength value of the loss peak. Its slope represents the sensitivity of the fiber as 0.00303 μm / °C (3.03 nm / °C), and the fitting parameter R 2 reaches 0.99889, indicating a very good linearity.

[0039] As a representative ethanol-filled negative-curvature fiber single-polarization temperature sensor, the implementation examples are as follows:

[0040] Example 1: The major semi-axis of the 8 elliptical quartz glass tubes is d1 = 34 μm. The minor semi-axis of the 8 elliptical quartz glass tubes is d2 = 20 μm. The thickness of the 8 elliptical quartz glass tubes is t = 0.4 μm. The angle between adjacent tube rings of the 8 elliptical quartz glasses is 44.5 degrees. The fiber radius R = 69 μm.

[0041] Example 2: The major semi-axis of the 8 elliptical quartz glass tubes is d1 = 36 μm. The minor semi-axis of the 8 elliptical quartz glass tubes is d2 = 22 μm. The thickness of the 8 elliptical quartz glass tubes is t = 0.6 μm. The angle between adjacent tube rings of the 8 elliptical quartz glasses is 45.5 degrees. The fiber radius R = 71 μm.

[0042] Embodiment 3: The major semi-axis of the inner part of 8 elliptical quartz glass tubes is d1 = 35 μm. The minor semi-axis of the inner part of 8 elliptical quartz glass tubes is d2 = 21 μm. The thickness of 8 elliptical quartz glass tubes is t = 0.5 μm. The included angle between adjacent tube rings of 8 elliptical quartz glasses is 45 degrees. The radius of the optical fiber is R = 70 μm.

[0043] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or equivalently replace some of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An ethanol-filled single-polarization temperature sensor for negative-curvature optical fiber, characterized in that Comprising: A cladding region and a core region; The cladding region includes 8 elliptical quartz glass tubes arranged uniformly. The major axis of the elliptical quartz glass tube is d1 and the minor axis is d2; the thickness of the elliptical quartz glass tube is t, and the range of the thickness t of the elliptical quartz glass tube is: 0.4μm to 0.6μm; the included angle between adjacent elliptical quartz glass tubes is 44.5 to 45.5 degrees; among them, the filling material of 6 elliptical quartz glass tubes is ethanol, and the filling material of 2 elliptical quartz glass tubes is gold; the interval between the 2 elliptical quartz glass tubes filled with gold is 3 elliptical quartz glass tubes filled with ethanol, and the centers of the 2 elliptical quartz glass tubes filled with gold and the center of the optical fiber are on a straight line; The core region is the region surrounded by the 8 elliptical quartz glass tubes; The linear fitting equation of the wavelength position y where the loss peak of the sensor is located and the corresponding temperature x satisfies the following relationship: y = 0.00303x + 1.52605, and the goodness of fit R 2 of the linear fitting equation is 0.99889.

2. The sensor according to claim 1, wherein: The range of the major axis d1 in the elliptical quartz glass tube is: 34μm to 36μm.

3. The sensor according to claim 1, wherein: The range of the minor axis d2 in the elliptical quartz glass tube is: 20μm to 22μm.

4. The sensor according to claim 1, wherein: The included angle between adjacent elliptical quartz glass tubes is 45 degrees.

5. The sensor according to claim 1, characterized in that: The range of the radius R of the optical fiber is: 69μm to 71μm.

6. The sensor according to claim 1, characterized in that: The filling material of the core region is ethanol.

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