A bow-tie dual-resonance ring micro-nano fiber capable of simultaneously measuring temperature and pressure, and a preparation method and a measuring method thereof

Abstract

The application provides a bow-shaped dual-resonance ring micro-nano optical fiber capable of simultaneously measuring temperature and pressure, a preparation method and a measuring method, and belongs to the field of micro-nano optical fibers. In order to solve the problem that the existing micro-nano optical fiber cannot be simply used for dual-parameter measurement and the sensitivity of the measurement is low. The multiple interference angles generated by the ring-shaped optical fiber of the bow-shaped dual-resonance ring micro-nano optical fiber can realize the simultaneous measurement of temperature and pressure. The temperature change condition is detected by measuring the scattering light intensity or the frequency spectrum characteristics of the scattering light in the micro-nano optical fiber, and the pressure applied on the micro-nano optical fiber is detected by monitoring the transmission loss or the transmission delay change in the micro-nano optical fiber. The micro-nano optical fiber has the advantages of small size, low loss, flexibility, high sensitivity and multifunctionality.

Description

Technical Field

[0001] This invention relates to the field of micro-nano fiber optic technology, and more specifically, to a bow-shaped dual-resonant ring micro-nano fiber optic sensor capable of simultaneously measuring temperature and pressure, as well as its fabrication and measurement methods. Background Technology

[0002] Micro- and nano-fiber optic sensors are a technology that utilizes micro- and nano-scale fiber optic structures for sensing. They typically detect changes in target physical quantities, such as temperature, pressure, humidity, water hardness, stress, wind direction, and underwater acoustics, by monitoring changes in optical signals. Micro- and nano-fiber optic sensors offer advantages such as high sensitivity, high resolution, fast response, and good stability. Their applications are wide-ranging, including biosensing, patient monitoring, monitoring and controlling parameters such as temperature, pressure, and humidity in production processes, and detecting pressure and temperature parameters in oil wells and pipelines. Micro- and nano-fiber optic sensors can simultaneously measure temperature and pressure evolution processes; common methods for achieving this include fiber Bragg grating (FBG) sensors, fiber micro-bend sensors, and fiber interferometer sensors. In the late 1980s and early 1990s, researchers began exploring the potential of fiber micro-bends in sensing applications. Early work focused primarily on theoretical analysis and experimental verification. G. Meltz et al. introduced a method for fabricating Bragg gratings using fiber micro-bends, laying the foundation for subsequent research on fiber micro-bend sensors. With technological advancements, researchers have continuously improved the design and fabrication processes of fiber micro-bend sensors to enhance their sensitivity, stability, and application range.

[0003] In recent years, fiber optic microbending sensors have been widely used in structural health monitoring, environmental monitoring, and biomedicine, with numerous research papers addressing these areas. Novel fiber optic sensor structures have also been proposed to address issues such as temperature compensation, improved sensitivity, and stability, achieving positive application results in aerospace, wearable monitoring systems, and high-temperature environments. Among these, research findings on miniature high-temperature fiber optic sensors based on advanced packaged Fabry-Perot interferometers and temperature-compensated fiber optic microbending sensors based on twisted multimode fibers demonstrate the potential of fiber optic microbending sensors in various application scenarios. Furthermore, research on novel fiber optic sensor structures such as superfiber loops, ultralong-period microfiber gratings, and ultrafine fiber Mach-Zehnder interferometers provides new ideas and possibilities for the development of fiber optic sensors. Recent research results include sensors that simultaneously measure seawater pressure and temperature, flexible fiber optic sensors capable of simultaneously measuring temperature and pressure, and novel sensors that utilize dual-interference microfiber resonators to measure air pressure and temperature. These achievements provide a solid foundation for future research on micro / nano fiber optic sensors.

[0004] However, the micro-nano fiber structures used in current micro-nano fiber sensors are basically linear, resulting in relatively low measurement sensitivity. Summary of the Invention

[0005] The technical problem to be solved by this invention is:

[0006] To address the problem that existing micro- and nano-fibers cannot easily perform dual-parameter measurements and have low measurement sensitivity.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0008] This invention provides a bow-shaped dual-resonant ring micro / nano fiber capable of simultaneously measuring temperature and pressure. The micro / nano fiber is a one-piece bow-shaped structure comprising two ring fibers with different bending radii r1 and r2. Both ring fibers are resonant ring structures, and their outer edges are joined together at the connection point. Two bent fibers are connected at the connection point, with the two bent fibers bending in opposite directions. A broadband light source is input from one bent fiber, loops around the same-side ring fiber, then around the other-side ring fiber, and finally outputs from the other bent fiber. The light is then monitored and analyzed in real time by a spectrometer to detect changes in temperature and pressure.

[0009] Furthermore, both the loop fiber and the bent fiber are single-mode fibers, and the single-mode fibers are wrapped with PDMS layers on both the top and bottom sides.

[0010] Furthermore, the single-mode optical fiber has a diameter of 2μm, the total length of the integrally formed micro-nano optical fiber is 30mm, and the thickness of the PDMS layer is 300μm.

[0011] A method for fabricating a bow-shaped dual-resonant ring micro / nano optical fiber capable of simultaneously measuring temperature and pressure includes the following steps:

[0012] Single-mode optical fiber was stretched to a diameter of 2μm-3μm and a waist length of 30mm-33mm using a flame melting and stretching process to obtain micro / nano optical fiber. 2ml of prepared PDMS was spread flat on a mold, and the mold with the spread PDMS was placed on a heating stage for curing. The thickness of the cured PDMS film was controlled to be below 300μm. The micro / nano optical fiber was coiled into a bow shape and placed on the cured PDMS film. Another layer of PDMS was then covered and the film was heated and fixed repeatedly to finally obtain a bow-shaped dual resonant ring micro / nano optical fiber.

[0013] A measurement method for a bow-shaped dual-resonant ring micro / nano optical fiber capable of simultaneously measuring temperature and pressure includes the following steps:

[0014] S100, Pre-processing: Place the bow-shaped dual-resonant ring micro / nano optical fiber on a PDMS film and cover it with a layer of PDMS to fabricate the sensor. Place the sensor in the measurement area and connect it to a broadband light source and spectrometer.

[0015] S200, pressure measurement: When the bow-shaped double resonant ring micro / nano fiber is subjected to pressure from the external environment or external mechanical force applied around the micro / nano fiber, the intensity or arrival time of the output light signal is detected by a spectrometer to infer the magnitude of the pressure.

[0016] S300 Temperature measurement: As the temperature changes, the intensity of scattered light inside the optical fiber or the spectral characteristics of the scattered light are detected by a spectrometer to infer the temperature change.

[0017] Furthermore, when sensing changes in external parameters by monitoring the displacement of the resonant wavelength, specifically...

[0018] The resonance condition of the resonant ring is Ln eff =mλ, where L is the length of the resonant ring, n eff λ is the effective refractive index of the resonant mode, and λ is the resonant wavelength.

[0019] The resonant peak frequency f of the resonant ring depends on its length L and refractive index n. eff L is calculated using the formula for the resonant peak frequency:

[0020]

[0021] Where c is the speed of light;

[0022] When the pump light frequency f p The optimal resonance effect is achieved when the frequency equals the resonant peak frequency f of the resonant ring. The resonance condition formula is:

[0023] f p =f (2)

[0024] The Q-factor is used to describe the energy loss of a resonant system. The relationship between the Q-factor and the resonant ring is as follows: Where Δf is the bandwidth on the resonance curve.

[0025] Furthermore, the optical sensing performance of micro / nano fibers can be improved by changing their diameter, including...

[0026] The transmission mode of micro / nano optical fibers is as follows:

[0027]

[0028] Where V is the normalized frequency, a is the radius of the micro / nano fiber, ω is the wavelength of the guiding light, and Δn is the refractive index difference between the micro / nano fiber material and the surrounding material.

[0029] The bending loss of micro / nano optical fibers is related to their diameter and bending radius:

[0030]

[0031] Where, α b For bending loss, n c denoted as the core refractive index, k0 as the wave vector in vacuum, R as the radius of curvature of the micro / nano fiber, and Λ as the bending period of the micro / nano fiber.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] This invention discloses a bow-shaped dual-resonant ring micro / nano-fiber capable of simultaneously measuring temperature and pressure, along with its fabrication and measurement methods. The multiple independent interference tilt angles generated by the ring-shaped fiber with its dual-resonant ring structure enable simultaneous measurement of temperature and pressure. Experiments show that the spectrum exhibits corresponding regular changes when the temperature and pressure are altered. Therefore, temperature changes can be detected by measuring the intensity or spectral characteristics of scattered light within the micro / nano-fiber, and the magnitude of pressure applied to the micro / nano-fiber can be detected by monitoring changes in transmission loss or transmission delay within the micro / nano-fiber.

[0034] The micro / nano sensor of this invention uses a dual-resonant ring structure, which improves temperature sensitivity compared to traditional micro / nano fiber structures. Besides achieving high-sensitivity measurements, the special design of the resonant ring structure enables rapid optical signal response, giving it advantages in real-time monitoring and sensing applications. In this sensor, temperature changes can cause micro-bending of the optical fiber, which affects the light transmission characteristics. Temperature changes can be deduced by measuring changes in the resonant wavelength in the spectrum. Pressure causes minute deformation of the optical fiber, thereby altering the light transmission path and characteristics. These changes can be detected by the fiber micro-bending sensor, allowing for synchronous demodulation of temperature and pressure through a correlation function.

[0035] The bow-shaped dual-resonant ring micro / nano fiber proposed in this invention has been experimentally proven to have a temperature sensitivity of -2.4033 nm / ℃, which is significantly improved compared to other existing sensors; its pressure sensitivity can reach -4.8863 dBm / kPa; it has the advantages of small size, low loss, flexibility, high sensitivity and multifunctionality, and is suitable for applications that require miniaturization or integration. It has broad application prospects in the fields of optical communication, sensing technology, medical diagnosis and optical imaging. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of the bow-shaped dual-resonance ring micro / nano optical fiber in an embodiment of the present invention;

[0037] Figure 2The images shown are actual pictures of the stretched single-mode optical fiber and the sensor in this embodiment of the invention.

[0038] Figure 3 This is a diagram illustrating the sensor manufacturing process in an embodiment of the present invention;

[0039] Figure 4 This is a structural diagram of the temperature and pressure measurement experiment using a bow-shaped dual-resonance ring micro / nano optical fiber in an embodiment of the present invention.

[0040] Figure 5 These are temperature reflectance spectrum curves at different wavelengths in embodiments of the present invention;

[0041] Figure 6 This is a linear fitting curve of spectral migration and temperature change in an embodiment of the present invention;

[0042] Figure 7 These are pressure reflection spectrum curves at different wavelengths in embodiments of the present invention;

[0043] Figure 8 This is a linear fitting curve of spectral migration and pressure change in an embodiment of the present invention.

[0044] Figure label:

[0045] 1. Loop fiber; 2. Bending fiber; 3. Connection point. Detailed Implementation

[0046] In the description of this invention, it should be noted that the terms used in the various embodiments, such as "upper," "lower," "front," "rear," "left," and "right," which indicate orientation, are only used to simplify the description of the positional relationships based on the accompanying drawings and do not mean that the components and devices referred to must be operated in accordance with the specific orientations and defined operations, methods, and structures in the specification. Such directional terms do not constitute a limitation of this invention.

[0047] In the description of this invention, it should be noted that the terms "first," "second," and "third" mentioned in the embodiments of this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," and "third" may explicitly or implicitly include one or more of that feature.

[0048] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0049] Specific Implementation Plan 1: Combining Figure 1 and Figure 2As shown, this invention provides a bow-shaped dual-resonant ring micro / nano optical fiber capable of simultaneously measuring temperature and pressure. The micro / nano optical fiber is a monolithically formed bow-shaped structure comprising two ring-shaped optical fibers 1 with different bending diameters. Both ring-shaped optical fibers 1 are resonant ring structures, and their outer edges are joined at a connection point 3. The connection point 3 is maintained by electrostatic force or van der Waals force. Two bent optical fibers 2 are connected to the connection point 3, with opposite bending directions, for connecting a broadband light source and a spectrometer. The device combining the broadband light source and the spectrometer is... Figure 4 As shown, the broadband light source is input from the curved optical fiber 2 on one side, then goes around the loop optical fiber 1 on the same side, then around the loop optical fiber 1 on the other side, and finally outputs from the curved optical fiber 2 on the other side. The light source is monitored and analyzed in real time by a spectrometer, thereby realizing the detection of temperature and pressure changes.

[0050] Because the two looped optical fibers 1 with different bending radii generate multiple independent interference tilt angles, they can be used to simultaneously measure temperature and pressure. Simultaneously, the two looped optical fibers 1 also form two resonant ring structures. A resonant ring (MNF) is an optical device consisting of a ring waveguide. Its working principle utilizes the reflection of light within the waveguide within the ring structure to form a standing wave, thereby achieving optical signal filtering, transmission, and modulation. The resonant ring uses the enclosed optical interference bus fiber to transmit light waves. When external parameters change, the effective refractive index and length of the microfiber ring also change accordingly, causing a shift in the resonant wavelength in the output spectrum. Therefore, the resonant rings configured in this invention can sense changes in external parameters by monitoring the displacement of the resonant wavelength. These changes in external parameters refer to variations in temperature and pressure, specifically:

[0051] The resonance condition of the resonant ring is: Ln eff =mλ, that is, the length L of the resonant ring and the effective refractive index n of the resonant mode. eff The product should be an integer multiple of the resonant wavelength λ; m is an integer coefficient.

[0052] The resonant peak frequency f of a resonant ring can be determined by its length L and refractive index n. eff L is calculated using the formula for the resonant peak frequency:

[0053]

[0054] Where c is the speed of light;

[0055] When the pump light frequency f p The optimal resonance effect can only be achieved when the frequency equals the resonant peak frequency f of the resonant ring. The resonance condition formula is:

[0056] f p =f (2)

[0057] The Q factor is a parameter describing the degree of energy loss in a resonant system, and its relationship with the resonant ring is as follows: Where f is the resonant frequency and Δf is the bandwidth on the resonant curve;

[0058] Specifically, the Q factor can be used to measure the quality factor of a resonant ring; the larger the Q factor, the stronger the energy storage capacity of the resonant system, the smaller the corresponding energy loss, the sharper the resonance curve, and the better the selectivity and stability of the resonant system.

[0059] Due to the brittleness of micro- and nano-fibers, their diameters must be drawn to 2 μm or less to be used in fabricating bow-shaped structures. Drawing fibers into micro- and nano-fibers improves the measurement accuracy of sensors. Since micro- and nano-fibers typically have diameters ranging from a few micrometers to hundreds of nanometers, their tiny size allows the light field to be localized within the fiber core, thus enhancing the interaction between light and the analyte. This enhanced localization results in higher sensitivity, enabling effective measurements even with very small sample sizes. As the diameter of micro- and nano-fibers becomes smaller, approaching or even smaller than the wavelength of light propagating within them, materials with low refractive indices surrounding the fiber can provide even better optical sensing performance. Such micro- and nano-fibers exhibit tight light confinement, high fractional evanescent field, and low bending loss.

[0060] Preferably, the transmission mode of micro / nano optical fibers can be described by the following formula:

[0061]

[0062] Where V is the normalized frequency (V-number), a is the radius of the micro / nano fiber, ω is the wavelength of the guiding light, and Δn is the refractive index difference between the micro / nano fiber material and the surrounding material;

[0063] When the diameter of micro / nano fibers is close to or smaller than the wavelength of light, the V-number decreases, resulting in a stronger confinement effect and a higher fractional evanescent field.

[0064] Furthermore, the bending loss of micro / nano optical fibers is also related to their diameter and bending radius, and can be described by the following formula:

[0065]

[0066] Where, α b It is bending loss, n c Λ is the core refractive index, k0 is the wave vector in vacuum, R is the radius of curvature of the micro / nano fiber, and Λ is the bending period of the micro / nano fiber.

[0067] The smaller the diameter of micro- and nano-fibers, the lower the bending loss, which makes them better suited for fabricating high-sensitivity optical sensors.

[0068] Specific Implementation Plan Two: Combining Figure 1 and Figure 2 As shown, this invention provides a method for fabricating a bow-shaped dual-resonant ring micro / nano optical fiber capable of simultaneously measuring temperature and pressure, comprising the following steps:

[0069] Single-mode optical fibers were stretched to a diameter of 2μm-3μm and a waist length of 30mm-33mm using an oxyhydrogen flame melting and stretching process to obtain micro / nano fibers. 2ml of prepared PDMS was spread evenly on a mold, and the mold with the PDMS was placed on a heating stage for curing. The thickness of the cured PDMS film was controlled to be below 300μm. The micro / nano fibers were then coiled into a bow shape and placed on the cured PDMS film, and another layer of PDMS was applied. The process was repeated with heating to fix the fibers, ultimately yielding a bow-shaped dual-resonant ring micro / nano fiber. The PDMS used was polydimethylsiloxane.

[0070] It should be noted that although the fabrication of the freestanding ultra-fine fiber resonant ring is relatively easy, the ring is mechanically fragile because its structure relies on van der Waals forces and electrostatic forces in the joint region. Furthermore, this invention requires the fabrication of a double-ring structure, which necessitates PDMS encapsulation. The deformation of PDMS with temperature can also be used to assist in temperature measurement.

[0071] like Figure 2 As shown in (b), the bending radius r1 of one side of the bow-shaped double resonant ring micro / nano fiber 1 is 2.32 mm, and the bending radius r2 of the other side of the ring fiber 1 is 1.15 mm.

[0072] Specific Implementation Plan Three: Combining Figures 1 to 7 As shown, this invention provides a measurement method for a bow-shaped dual-resonant ring micro / nano optical fiber capable of simultaneously measuring temperature and pressure, comprising the following steps:

[0073] S100, Pre-processing: Place the bow-shaped double resonant ring micro / nano optical fiber on the prepared PDMS film and cover it with a layer of PDMS to make a sensor. Place the sensor in the measurement area and connect it to the broadband light source and spectrometer.

[0074] S200, Pressure Measurement: When micro-nano optical fibers are subjected to pressure from the external environment or external mechanical forces applied around them, the tiny bending of the micro-nano optical fibers causes a tiny shift or twist in the transmission path of the light in the micro-nano optical fibers, which in turn causes changes in the transmission loss of the optical signal or changes in the transmission delay of the optical signal in the optical fiber. The magnitude of the pressure is inferred by detecting the intensity or arrival time of the signal using a spectrometer.

[0075] Fiber optic sensors typically use optical devices to monitor changes in these transmission characteristics; for example, light signals are sent into the fiber optic cable via a light source, and then a spectrometer is used to detect the signal intensity or arrival time; when the fiber optic cable is subjected to pressure, these parameters change, allowing the magnitude of the pressure to be inferred.

[0076] S300. Temperature measurement: As temperature changes, the optical scattering characteristics inside the micro / nano fiber also change accordingly, including: increased temperature causes PDMS deformation, thus affecting its refractive index n. c This causes more scattering to affect the propagation of light, and the resonant wavelength of the resonant ring will shift; temperature changes also increase the non-uniformity in the optical fiber, resulting in changes in the distribution pattern and intensity of scattered light; by detecting the intensity or spectral characteristics of scattered light inside the optical fiber using a spectrometer, the temperature changes can be indirectly reflected.

[0077] As temperature increases, the intensity of scattered light usually increases, or the spectral distribution of scattered light shifts; this change can be monitored and analyzed in real time by instruments such as spectrometers, thereby enabling the detection and measurement of temperature changes.

[0078] The other combinations and connections in this implementation scheme are the same as in Specific Implementation Scheme 1.

[0079] The micro / nano sensor of this invention utilizes a dual-resonant ring structure, which improves temperature sensitivity compared to traditional micro / nano fiber structures. Besides achieving high-sensitivity measurements, the special design of the resonant ring structure enables rapid optical signal response, giving it advantages in real-time monitoring and sensing applications. In this sensor, temperature changes cause micro-bending of the optical fiber, which affects light transmission characteristics. Temperature changes can be deduced by measuring changes in the resonant wavelength in the spectrum. Pressure causes minute deformation of the optical fiber, thereby altering the light transmission path and characteristics. These changes can be detected by the fiber micro-bending sensor, allowing for synchronous demodulation of temperature and pressure using a correlation function; the correlation function is... Figure 6 In the equation y1 = -2.4033x1 + 1656.08, and... Figure 8 In the formula y2 = -4.8863x2 - 47.08, y1 represents intensity, y2 represents wavelength, x1 represents temperature, and x2 represents pressure. The temperature and pressure parameters can be obtained by substituting the data.

[0080] experiment

[0081] Fabrication of bow-shaped double-resonant ring micro / nano optical fibers:

[0082] Corning single-mode fiber (core diameter 8μm, cladding diameter 125μm) was stretched to a diameter of 2μm and a waist length of 30mm using a thermoforming stretching process. Figure 2 As shown in (a); to fabricate a PDMS film, 2 ml of prepared PDMS was spread evenly on a mold, and the PDMS was placed on a heating stage for curing. The thickness of the fabricated PDMS film was controlled to be below 300 μm. Micro-nano optical fibers were coiled into a bow shape and placed on the PDMS film, and then another layer of PDMS was applied to fix it. The fabrication steps are visualized as follows. Figure 3 As shown; the fabricated bow-shaped dual-resonant ring micro / nano optical fiber... Figure 1 As shown, the radius r1 of BMFS is 2.32mm, and r2 is 1.15mm; at this point, the sensor part is complete, and the actual object is shown in the figure. Figure 2 (b)

[0083] Measurement Experiment:

[0084] Experimental setup such as Figure 4 As shown, a broadband light source (NIPXI 4844) and an OSA (Optical Distortion Spectrometer) were used to test the sensor performance. The light source has a wavelength range of 1510 nm to 1590 nm and a bandwidth of 80 nm. The OSA's wavelength sampling step size was set to 4 pm, with a stability of 1 pm. After the light is emitted from the broadband light source, it is transmitted through optical fiber to the sensing area of ​​the micro / nano fiber, where the light is detected. In this system, the light source provides a wide wavelength range, allowing coverage of multiple required optical frequencies. The OSA is responsible for demodulating and analyzing the optical signal to extract the desired information. This configuration is commonly used in applications such as fiber optic sensors to achieve high-precision measurement and analysis of optical signals.

[0085] result:

[0086] The temperature performance of the temperature test sensor is modified by using a constant temperature chamber. The sensor is placed inside the chamber, and the temperature is increased from 36℃ to 37℃ in increments of 0.1℃. The reflectance spectrum is then recorded. The temperature reflectance spectrum is as follows: Figure 5 As shown, it can be concluded that when the temperature rises, the effective refractive index of the microfiber ring changes, resulting in a blue shift in the resonant wavelength of the output spectrum. Figure 6 The linear fitting curve of spectral migration and temperature change is shown. The sensitivity of temperature determination by the reflectance spectrum and the linear fitting curve is -2.4033 nm / ℃.

[0087] Pressure measurements were performed on the BMFS by recording the reflectance spectrum by varying the pressure applied to the sensor, with pressure changes starting at 0.1 kPa and increasing in increments of 0.1 kPa to 0.6 kPa; the pressure reflectance spectrum is shown below. Figure 7 As shown, when the pressure gradually increases, the tiny bending of the micro-nano fiber causes a slight deflection or twist in the transmission path of light in the micro-nano fiber, resulting in a decrease in the intensity of the spectrum. Figure 8The linear fitting curve of spectral migration and pressure change is shown. The sensitivity of pressure measurement by using the reflectance spectrum and the linear fitting curve is -4.886 dBm / kPa.

[0088] according to Figure 6 as well as Figure 7 The data results show that the overall fitting error is less than 2.4% for temperature measurement and less than 1.4% for pressure measurement. This indicates that even when measuring both temperature and pressure simultaneously, the sensor performance still meets high accuracy requirements, and crosstalk effects can be ignored. Furthermore, the temperature resolution in this study is 0.0017℃.

[0089] In addition, the sensing performance of different sensors for temperature and pressure was compared, and the specific results are shown in Table 1 below.

[0090] Table 1

[0091]

[0092] Table 1 shows a direct comparison of the BMFS of this invention with other existing sensors, providing its temperature and pressure performance, including temperature sensitivity, pressure sensitivity, and the ability to simultaneously measure temperature and pressure. It is evident that the bow-shaped dual-resonant ring structure exhibits a significant advantage in temperature sensitivity compared to bendless micro / nano fibers, FBGs (Fabry-Perot interferometers), Sagnac rings, superfiber knots, and single-resonant ring micro / nano fibers.

[0093] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A bow-shaped dual-resonant ring micro / nano optical fiber capable of simultaneously measuring temperature and pressure, characterized in that: The micro / nano optical fiber is a one-piece, bow-shaped structure, including two bending radii r. 1、 r2 different ring optical fibers (1), both ring optical fibers (1) are resonant ring structures, the outer edges of the two ring optical fibers (1) are connected, the connection point is a connection point (3), the connection point (3) is connected to two bent optical fibers (2), the two bent optical fibers (2) are bent in opposite directions, and are used to input from the bent optical fiber (2) on one side through a broadband light source, then go around the ring optical fiber (1) on the same side, then go around the ring optical fiber (1) on the other side, and finally output from the bent optical fiber (2) on the other side. The light source is monitored and analyzed in real time by a spectrometer to realize the detection of temperature and pressure changes. Both the loop fiber (1) and the bent fiber (2) are single-mode fibers, and both the upper and lower sides of the single-mode fiber are wrapped with PDMS layers. The single-mode fiber has a diameter of 2μm, the total length of the integrally formed micro-nano fiber is 30mm, and the thickness of the PDMS layer is 300μm.

2. A method for fabricating a bow-shaped dual-resonant ring micro / nano optical fiber capable of simultaneously measuring temperature and pressure as described in claim 1, characterized in that, Includes the following steps: Single-mode optical fiber was stretched to a diameter of 2μm-3μm and a waist length of 30mm-33mm using a flame melting and stretching process to obtain micro / nano optical fiber. 2ml of prepared PDMS was spread flat on a mold, and the mold with the spread PDMS was placed on a heating stage for curing. The thickness of the cured PDMS film was controlled to be below 300μm. The micro / nano optical fiber was coiled into a bow shape and placed on the cured PDMS film. Another layer of PDMS was then covered and the film was heated and fixed repeatedly to finally obtain a bow-shaped dual resonant ring micro / nano optical fiber.

3. A measurement method for a bow-shaped dual-resonant ring micro / nano optical fiber capable of simultaneously measuring temperature and pressure, as described in claim 1, characterized in that... Includes the following steps: S100, Pre-processing: Place the bow-shaped double resonant ring micro / nano fiber on a PDMS film and cover it with a layer of PDMS to fabricate the sensor. Place the sensor in the measurement area and connect it to a broadband light source and spectrometer. S200, pressure measurement: When the bow-shaped double resonant ring micro / nano fiber is subjected to pressure from the external environment or external mechanical force applied around the micro / nano fiber, the intensity or arrival time of the output light signal is detected by a spectrometer to infer the magnitude of the pressure. S300 Temperature measurement: As the temperature changes, the intensity of scattered light inside the optical fiber or the spectral characteristics of the scattered light are detected by a spectrometer to infer the temperature change.

4. The measurement method for a bow-shaped dual-resonant ring micro / nano optical fiber capable of simultaneously measuring temperature and pressure according to claim 3, characterized in that: When changes in external parameters are sensed by monitoring the displacement of the resonant wavelength, specifically... The resonance condition of the resonant ring is Where, 𝐿 is the length of the resonant ring. is the effective refractive index of the resonant mode, is the resonant wavelength, and m is an integer coefficient; The resonant peak frequency ω of a resonant ring depends on its length φ and refractive index. The formula for calculating the resonant peak frequency is: 𝑓= (1) Where 𝑐 represents the speed of light; When the pump light frequency The optimal resonance effect is achieved when the frequency equals the resonant peak frequency ω of the resonant ring. The resonance condition formula is: （2） The Q-factor is used to describe the energy loss of a resonant system. The relationship between the Q-factor and the resonant ring is as follows: , where Δf is the bandwidth on the resonance curve.

5. The measurement method for a bow-shaped dual-resonant ring micro / nano optical fiber capable of simultaneously measuring temperature and pressure according to claim 4, characterized in that: Improving the optical sensing performance of micro- and nano-fibers by changing their diameter. include, The transmission mode of micro / nano optical fibers is as follows: （3） Where, 𝑉 is the normalization frequency, 𝑎 is the radius of the micro / nano fiber, ω is the wavelength of the guiding light, and Δ𝑛 is the refractive index difference between the micro / nano fiber material and the surrounding material. The bending loss of micro / nano optical fibers is related to their diameter and bending radius: （4） in, For bending loss, The refractive index of the fiber core, Let be the wave vector in vacuum, and let be the radius of curvature of the micro / nano optical fiber. The bending period of the micro / nano fiber.

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