Disclosure of Invention
Aiming at the defects and improvement needs of the prior art, the invention provides a flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor and a manufacturing method thereof, and aims to combine a sensitive material preparation method, fuse a novel composite sensitive material with a special optical fiber structure with a strong interference effect, and prepare an optical fiber temperature sensor with high sensitivity, strong stability and low cost by means of the temperature-sensitive performance of the flower-shaped ZnO/graphene material, so that the temperature detection problem in severe environments is better solved.
In order to achieve the purpose, the invention adopts the following technical scheme:
the flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor is characterized by comprising an ASE light source (1), an optical fiber circulator (2), a temperature sensing head (3) and a spectrometer (4).
The temperature sensing head (3) comprises a first single mode fiber (3-1), a multimode single sphere micro-nano fiber (3-2), a flower-shaped ZnO/graphene sensitive material (3-3), a second single mode fiber (3-4) and a metal aluminum film (3-5).
The temperature sensing head (3) takes a multimode single-sphere micro-nano optical fiber (3-2) as a temperature sensitive area, the multimode single-sphere micro-nano optical fiber (3-2) coats a temperature sensitive flower-shaped ZnO/graphene sensitive material (3-3), and is connected with a single mode fiber I (3-1) and a single mode fiber II (3-4) in an optical fiber fusion connection mode;
in the temperature sensing head (3), one end of a second single-mode fiber (3-4) is connected with the multimode single-sphere micro-nano fiber (3-2) in a melting mode, and the other end of the second single-mode fiber is coated with a metal aluminum film (3-5).
The multimode single-sphere micro-nano optical fiber (3-2) takes a multimode optical fiber as a main body, the multimode micro-nano optical fiber is firstly prepared, and then the multimode micro-nano optical fiber is burnt at the tapered part of the multimode micro-nano optical fiber by utilizing a method of melting and tapering by oxyhydrogen flame and then reversely adjusting a clamp, so that the structure is formed.
The ASE light source (1) is connected with the optical fiber circulator (2) through a single-mode optical fiber, the optical fiber circulator (2) is connected with the temperature sensing head (3) through the single-mode optical fiber, the optical fiber circulator (2) is connected with the spectrometer (4) through the single-mode optical fiber, and the single-mode optical fiber is connected with each device in an optical fiber fusion connection mode.
The flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor is characterized in that the output center wavelength of the ASE light source (1) is 1550nm, and the frequency bandwidth is 60 nm.
The flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor is characterized in that a flower-shaped ZnO/graphene sensitive material (3-3) in the temperature sensing head (3) is a temperature composite sensitive material.
The flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor is characterized in that a method for combining the multimode single-sphere micro-nano optical fiber (3-2) in the temperature sensing head (3) and the flower-shaped ZnO/graphene sensitive material (3-3) is a dripping method.
The preparation method of the flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor is characterized by comprising the following steps:
s1: preparing a multimode single-sphere micro-nano optical fiber (3-2), namely performing melt tapering on the multimode optical fiber with the length of 8cm and the fiber core diameter of 62.5 microns by using oxyhydrogen flame, and then performing treatment by using a method of reversely adjusting an optical fiber clamp in a heating state of the oxyhydrogen flame to prepare the multimode single-sphere micro-nano optical fiber (3-2);
s2: preparing a flower-shaped ZnO/graphene sensitive material (3-3), namely placing 15.0mg of graphene powder into 40mL of deionized water for ultrasonic dispersion for 2 hours, mixing the dispersed graphene solution with 3.5g of zinc nitrate, 4.8g of citric acid and 100mL of deionized water, stirring for 1.5 hours at the temperature of 75 ℃, placing the mixture into a constant-temperature drying box at the temperature of 90 ℃ for 1.5-2 hours, dripping 1.5mol/L of sodium hydroxide solution into the mixed solution, adjusting the pH value of the suspension to be 9.5, transferring the suspension into a reaction kettle, placing the reaction kettle into a constant-temperature drying box at the temperature of 125 ℃ for 15-16 hours, taking out the suspension, naturally cooling, washing a product with the deionized water for 4-5 times, and centrifuging for 15 minutes at 5000rmp/min to obtain a flower-shaped ZnO/graphene aqueous solution;
s3: preparing a single mode-tapering multi-mode-single mode fiber structure, intercepting two single mode fibers with the length of 5cm as a first single mode fiber (3-1) and a second single mode fiber (3-4), and connecting the first single mode fiber (3-1), the multi-mode single-sphere micro-nano fiber (3-2) and the second single mode fiber (3-4) in a fiber fusion connection mode to form the single mode-tapering multi-mode-single mode fiber structure;
s4: cladding of the metal aluminum film (3-5), namely truncating the end, which is not welded, of the second single-mode fiber (3-4) in the single-mode-tapered multi-mode-single-mode fiber structure, and cladding the metal aluminum film (2) with better reflection performance on the end;
s5: and (3) integrating a temperature sensing head (3), fixing a single-mode-tapered multi-mode-single-mode optical fiber structure which is manufactured but is not coated with a material in a dripping mode on a glass substrate, cleaning the glass substrate by using alcohol and deionized water to remove residual impurities, dripping flower-shaped ZnO/graphene aqueous solution along the surface of the multi-mode single-sphere micro-nano optical fiber (3-2), and putting the sensing head into a constant-temperature electrothermal blowing drying box for drying treatment to enable the sensitive material to be tightly combined with the multi-mode single-sphere micro-nano optical fiber (3-2) to form the temperature sensing head (3).
The flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor is characterized in that oxyhydrogen flame melting tapering is carried out in the step S1, a oxyhydrogen flame tapering machine is adopted to carry out melting tapering for 12.4mm, a multimode micro-nano optical fiber with the lumbar vertebra diameter of 6.92 mu m is formed, a clamp is adjusted back for 1mm, the multimode micro-nano optical fiber is burnt in the lumbar vertebra region through oxyhydrogen flame to melt spheres, and a multimode single-sphere micro-nano optical fiber (3-2) is formed, wherein the diameter of the single sphere is 13.1 mu m.
The flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor is characterized in that in the step S4 of coating the metal aluminum film (3-5), the length of the second single-mode optical fiber (3-4) after being truncated is 3 cm.
The flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor is characterized in that in the step S4 of coating the metal aluminum film (3-5), the thickness range of the metal aluminum film (2) is 80-200 mu m.
The flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor is characterized in that in the integration of the temperature sensing head (3) in the step S5, the temperature of the constant-temperature electrothermal blowing drying oven is set to be 45 ℃, and the heating time is 5 hours.
The beneficial effects of the invention are as follows:
the invention combines the preparation method of the sensitive material, fuses the novel composite sensitive material with a special optical fiber structure with a strong interference effect, and prepares the optical fiber temperature sensor with high sensitivity, strong stability and low cost by means of the temperature-sensitive performance of the flower-shaped ZnO/graphene material. The method has important significance for better solving the temperature detection problem in severe environments.
Detailed Description
The following description will further describe the specific embodiments of the present invention with reference to the accompanying drawings.
Referring to fig. 1, the flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor according to the embodiment is characterized by comprising an ASE light source (1), an optical fiber circulator (2), a temperature sensing head (3) and a spectrometer (4).
Referring to fig. 2, the temperature sensing head (3) comprises a first single mode fiber (3-1), a multimode single sphere micro-nano fiber (3-2), a flower-shaped ZnO/graphene sensitive material (3-3), a second single mode fiber (3-4) and a metal aluminum film (3-5).
The temperature sensing head (3) takes a multimode single-sphere micro-nano optical fiber (3-2) as a temperature sensitive area, the multimode single-sphere micro-nano optical fiber (3-2) coats a temperature sensitive flower-shaped ZnO/graphene sensitive material (3-3), and is connected with a single mode fiber I (3-1) and a single mode fiber II (3-4) in an optical fiber fusion connection mode;
in the temperature sensing head (3), one end of a second single-mode fiber (3-4) is connected with the multimode single-sphere micro-nano fiber (3-2) in a melting mode, and the other end of the second single-mode fiber is coated with a metal aluminum film (3-5).
The multimode single-sphere micro-nano optical fiber (3-2) takes a multimode optical fiber as a main body, the multimode micro-nano optical fiber is firstly prepared, and then the multimode micro-nano optical fiber is burnt at the tapered part of the multimode micro-nano optical fiber by utilizing a method of melting and tapering by oxyhydrogen flame and then reversely adjusting a clamp, so that the structure is formed;
the ASE light source (1) is connected with the optical fiber circulator (2) through a single-mode optical fiber, the optical fiber circulator (2) is connected with the temperature sensing head (3) through the single-mode optical fiber, the optical fiber circulator (2) is connected with the spectrometer (4) through the single-mode optical fiber, and the single-mode optical fiber is connected with each device in an optical fiber fusion connection mode.
The flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor is characterized in that the output center wavelength of the ASE light source (1) is 1550nm, and the frequency bandwidth is 60 nm.
The flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor is characterized in that a flower-shaped ZnO/graphene sensitive material (3-3) in the temperature sensing head (3) is a temperature composite sensitive material.
The flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor is characterized in that a method for combining the multimode single-sphere micro-nano optical fiber (3-2) in the temperature sensing head (3) and the flower-shaped ZnO/graphene sensitive material (3-3) is a dripping method.
The preparation method of the flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor is characterized by comprising the following steps:
s1: preparing a multimode single-sphere micro-nano optical fiber (3-2), namely performing melt tapering on the multimode optical fiber with the length of 8cm and the fiber core diameter of 62.5 microns by using oxyhydrogen flame, and then performing treatment by using a method of reversely adjusting an optical fiber clamp in a heating state of the oxyhydrogen flame to prepare the multimode single-sphere micro-nano optical fiber (3-2);
s2: preparing a flower-shaped ZnO/graphene sensitive material (3-3), namely placing 15.0mg of graphene powder into 40mL of deionized water for ultrasonic dispersion for 2 hours, mixing the dispersed graphene solution with 3.5g of zinc nitrate, 4.8g of citric acid and 100mL of deionized water, stirring for 1.5 hours at the temperature of 75 ℃, placing the mixture into a constant-temperature drying box at the temperature of 90 ℃ for 1.5-2 hours, dripping 1.5mol/L of sodium hydroxide solution into the mixed solution, adjusting the pH value of the suspension to be 9.5, transferring the suspension into a reaction kettle, placing the reaction kettle into a constant-temperature drying box at the temperature of 125 ℃ for 15-16 hours, taking out the suspension, naturally cooling, washing a product with the deionized water for 4-5 times, and centrifuging for 15 minutes at 5000rmp/min to obtain a flower-shaped ZnO/graphene aqueous solution;
s3: preparing a single mode-tapering multi-mode-single mode fiber structure, intercepting two single mode fibers with the length of 5cm as a first single mode fiber (3-1) and a second single mode fiber (3-4), and connecting the first single mode fiber (3-1), the multi-mode single-sphere micro-nano fiber (3-2) and the second single mode fiber (3-4) in a fiber fusion connection mode to form the single mode-tapering multi-mode-single mode fiber structure;
s4: cladding of the metal aluminum film (3-5), namely truncating the end, which is not welded, of the second single-mode fiber (3-4) in the single-mode-tapered multi-mode-single-mode fiber structure, and cladding the metal aluminum film (2) with better reflection performance on the end;
s5: and (3) integrating a temperature sensing head (3), fixing a single-mode-tapered multi-mode-single-mode optical fiber structure which is manufactured but is not coated with a material in a dripping mode on a glass substrate, cleaning the glass substrate by using alcohol and deionized water to remove residual impurities, dripping flower-shaped ZnO/graphene aqueous solution along the surface of the multi-mode single-sphere micro-nano optical fiber (3-2), and putting the sensing head into a constant-temperature electrothermal blowing drying box for drying treatment to enable the sensitive material to be tightly combined with the multi-mode single-sphere micro-nano optical fiber (3-2) to form the temperature sensing head (3).
The flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor is characterized in that oxyhydrogen flame melting tapering is carried out in the step S1, a oxyhydrogen flame tapering machine is adopted to carry out melting tapering for 12.4mm, a multimode micro-nano optical fiber with the lumbar vertebra diameter of 6.92 mu m is formed, a clamp is adjusted back for 1mm, the multimode micro-nano optical fiber is burnt in the lumbar vertebra region through oxyhydrogen flame to melt spheres, and a multimode single-sphere micro-nano optical fiber (3-2) is formed, wherein the diameter of the single sphere is 13.1 mu m.
The flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor is characterized in that in the step S4 of coating the metal aluminum film (3-5), the length of the second single-mode optical fiber (3-4) after being truncated is 3 cm.
The flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor is characterized in that in the step S4 of coating the metal aluminum film (3-5), the thickness range of the metal aluminum film (2) is 80-200 mu m.
The flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor is characterized in that in the integration of the temperature sensing head (3) in the step S5, the temperature of the constant-temperature electrothermal blowing drying oven is set to be 45 ℃, and the heating time is 5 hours.
The working principle is as follows:
flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor:
the working process is as follows: signal light is transmitted to a temperature sensing head (3) from an ASE light source (1) along a single mode fiber through a fiber circulator (2), in the temperature sensing head (3), the signal light is transmitted to a multimode single sphere micro-nano fiber (3-2) through a first single mode fiber (3-1), then transmitted to a second single mode fiber (3-3) through the multimode single sphere micro-nano fiber (3-2), reflected at a metal aluminum film (3-5) through the second single mode fiber (3-3), and then sequentially passes through the second single mode fiber (3-3), the multimode single sphere micro-nano fiber (3-2) and the first single mode fiber (3-1), and finally transmitted to a spectrometer (4) from the temperature sensing head (3) through the fiber circulator (2).
In the process of signal light transmission, the diameter of the fiber core of the multimode fiber is far larger than that of the common single-mode fiber, the fiber core of the multimode fiber can accommodate various light wave modes, and multimode interference effect can occur in different modes in the transmission process. In addition, the surface evanescent field of the multimode single-sphere micro-nano optical fiber after tapering and ball melting treatment is enhanced, the interaction between light and the external environment is increased when the light is transmitted in the multimode single-sphere micro-nano optical fiber, and particularly the interference effect in a single sphere is better. When signal light passes through the temperature sensing head (3), a series of mutually independent eigen modes are excited when the signal light is transmitted to the multimode single-sphere micro-nano optical fiber (3-2) through the first single-mode optical fiber (3-1), each mode interferes in the optical fiber, energy is redistributed, and when the signal light is transmitted to the second single-mode optical fiber (3-3) through the multimode single-sphere micro-nano optical fiber (3-2), optical coupling is formed and the signal light is transmitted in a fundamental mode. When the signal light reaches the metal aluminum film (3-5), the signal light is reflected and passes through the optical fiber structure formed by combining the second single-mode optical fiber (3-3), the multi-mode single-sphere micro-nano optical fiber (3-2) and the first single-mode optical fiber (3-1) again to form secondary interference, and finally the signal light is transmitted to the circulator from the first single-mode optical fiber (3-1) in a basic mode.
The difference in refractive index between the different modes is Δ n, the phase difference can be expressed as:
considering the inter-mode dispersion, the wavelength shift and external index relationship can be expressed as:
the dispersion factor is:
therefore, the sensitivity of the temperature sensor depends on the difference in effective refractive index and the dispersion factor between the modes. The invention adopts the multimode single-sphere micro-nano optical fiber (3-2), which has stronger sensitivity to the change of the external refractive index due to stronger evanescent field and smaller dispersion factor. In addition, the flower-like ZnO/graphene sensitive material (3-3) selected and prepared by the invention is very sensitive to temperature, and the structure of the material can be changed to a great extent by changing the temperature, so that the refractive index of the material is changed. The multimode single-sphere micro-nano optical fiber (3-2) is compounded with the flower-shaped ZnO/graphene sensitive material (3-3), and the single mode-tapered multimode-single mode and the metal aluminum film (3-5) are combined to enable the signal light to form secondary interference, so that the temperature sensitivity of the temperature sensing head (3) is greatly enhanced, and the temperature sensor has high sensitivity and stability.
The effect of the invention is demonstrated by the following examples:
the temperature sensing head (3) of the flower-shaped ZnO/graphene single-sphere micro-nano structure temperature sensor is placed in a constant-temperature drying oven for heating test, when the temperature rises, the effective refractive index of the optical fiber of the sensing part, which is the combination of the multimode single-sphere micro-nano optical fiber (3-2) and the flower-shaped ZnO/graphene sensitive material (3-3), will change accordingly, and the interference spectrum will have obvious and regular drift along with the rise of the temperature. FIG. 3 is a graph showing the drift of the interference spectrum of the temperature sensor at different temperatures, wherein the directions of arrows indicate the temperatures of the curves from the top to the bottom, respectively, at 32 deg.C, 34 deg.C, 36 deg.C, 38 deg.C, 40 deg.C, 42 deg.C, 44 deg.C, 46 deg.C, and 48 deg.C. Fig. 4 is a data fitting graph of interference spectrum in temperature experiment, and the selected data points are peaks and peaks of interference spectrum at different temperatures within the dotted line frame in fig. 3, where the slope is 0.13867 and the goodness of fit is 0.99048.
As can be seen from fig. 4, the interference spectrum of the temperature sensor shifts with a significant regularity as the temperature increases. In addition, the sensitivity of the sensor to the temperature can be obtained by processing the data of the interference spectrum drift amount and the temperature change in the temperature experiment, and the sensitivity can reach 138.67 pm/DEG C.