A kind of all-solid-state temperature sensing device and system based on optical fiber concave high reflection optical film

Abstract

The application discloses a kind of based on optical fiber concave high reflection optical film's all solid state temperature sensing device and system, temperature sensing device includes laser, optical fiber attenuator, optical fiber microcavity, optical fiber coupler, first photoelectric detector and second photoelectric detector, the optical fiber microcavity is made of first optical fiber concave mirror and second optical fiber concave mirror, the first optical fiber concave mirror and second optical fiber concave mirror are formed by high reflection optical film after being prepared into concave by optical fiber end face, the concave of the first optical fiber concave mirror and second optical fiber concave mirror is opposite, the first optical fiber concave mirror and second optical fiber concave mirror are filled with solid-state thermal expansion material, laser emitted by the laser enters optical fiber coupler by optical fiber attenuator, the optical fiber coupler is divided into first light beam and second light beam by laser output light beam, first light beam enters first photoelectric detector by optical fiber microcavity, second light beam directly enters second photoelectric detector.The application has high response degree and sensitivity.

Description

Technical Field

[0001] This invention relates to temperature sensors, and more particularly to an all-solid-state temperature sensing device and system based on a high-reflectivity optical film on a concave surface of an optical fiber. Background Technology

[0002] Temperature, as a fundamental physical parameter, plays a crucial role in scientific research, industrial production, and daily life. High-sensitivity temperature measurement technology is essential for fields such as nanoscale thermal imaging and sensing, integrated circuits, energy harvesting, environmental monitoring, and biomedicine. In particular, integrating high-sensitivity temperature sensors into microscale devices is of great significance for the application and research of measuring localized temperature changes. Currently, various methods have been developed to improve the sensitivity of temperature measurements, including nanoscale temperature sensors based on superconducting quantum interference devices (SQIs), with diameters less than 50 nm and sensitivity reaching 870 nk Hz. -1 / 2 However, this temperature sensor requires low-temperature operation and has limited sensitivity. To achieve higher sensitivity temperature measurement at room temperature, researchers developed a temperature sensor using a FP cavity. The FP cavity is filled with liquid, and temperature sensing is achieved by the liquid expanding at different temperatures, causing the cavity length to increase and resulting in a shift in the center wavelength of the transmission spectrum. Examples include 201910454405.5, 201720373255, and 202110310914.8. However, the sensitivity of this technology still needs further improvement, and temperature measurement requires scanning all wavelengths before calculating the center wavelength of the transmission spectrum, thus determining the temperature based on the relationship between the center wavelength of the transmission spectrum and temperature, resulting in a significant time delay. Summary of the Invention

[0003] To address the problems existing in the prior art, the purpose of this invention is to provide a more sensitive all-solid-state temperature sensing device based on a high-reflectivity optical film on a concave surface of an optical fiber.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] A solid-state temperature sensing device based on a high-reflectivity optical film on a concave fiber optic surface includes a laser, a fiber optic attenuator, a fiber optic microcavity, a fiber optic coupler, a first photodetector, and a second photodetector. The fiber optic microcavity is composed of a first concave fiber optic mirror and a second concave fiber optic mirror. Both the first and second concave fiber optic mirrors are formed by depositing a high-reflectivity optical film on the concave end face of an optical fiber. The concave surfaces of the first and second concave fiber optic mirrors face each other, and the space between the first and second concave fiber optic mirrors is filled with a solid thermal expansion material. The laser emitted by the laser enters the fiber optic coupler through the fiber optic attenuator. The fiber optic coupler splits the laser beam into a first beam and a second beam. The first beam enters the first photodetector through the fiber optic microcavity, and the second beam directly enters the second photodetector.

[0006] Furthermore, the fiber coupler splits the laser into a first beam and a second beam with a splitting ratio of 90:10.

[0007] Furthermore, the fiber optic microcavity is an FP cavity. Furthermore, the first fiber optic concave mirror is connected to the fiber optic coupler via an optical fiber, and the second fiber optic concave mirror is connected to the first photodetector via an optical fiber.

[0008] Furthermore, the high-reflectivity optical film is a 99.9% reflectivity dielectric film.

[0009] A solid-state temperature sensing system based on a high-reflectivity optical film on a concave surface of an optical fiber includes the aforementioned solid-state temperature sensing device and a temperature calculation module. The temperature calculation module is used to calculate the transmission spectrum of the optical fiber microcavity based on the optical power detected by the first and second photodetectors when the laser scans within a preset wavelength range. The center wavelength of the transmission spectrum is then substituted into a pre-stored curve showing the relationship between the center wavelength of the transmission spectrum and temperature to calculate the current real-time temperature.

[0010] Furthermore, the temperature calculation module specifically includes:

[0011] The relationship curve storage unit is used to store the relationship curve between the center wavelength of the transmission spectrum of the current all-solid-state temperature sensing device and the temperature.

[0012] The real-time transmission spectrum calculation unit is used to obtain the optical power detected by the first photodetector and the second photodetector when the laser scans within a preset wavelength range, calculate the ratio of the optical power detected by the first photodetector and the second photodetector at each wavelength, and use it as the transmittance at each wavelength to form a transmission spectrum.

[0013] The real-time center wavelength calculation unit obtains the wavelength where the transmittance peak is located in the transmission spectrum, and uses it as the real-time center wavelength of the transmission spectrum.

[0014] The real-time temperature calculation unit is used to substitute the center wavelength of the transmission spectrum into the relationship curve between the center wavelength of the transmission spectrum and temperature to find the real-time temperature.

[0015] A solid-state temperature sensing system based on a high-reflectivity optical film on a concave surface of an optical fiber includes the aforementioned solid-state temperature sensing device and a temperature calculation module. The temperature calculation module is used to calculate the real-time transmittance of the optical fiber microcavity based on the optical power detected by the first photodetector and the second photodetector, calculate the real-time thermal transmission coefficient based on the real-time transmittance, and substitute the real-time thermal transmission coefficient into the relationship curve between the thermal transmission coefficient and temperature to calculate the current real-time temperature.

[0016] Furthermore, the temperature calculation module specifically includes:

[0017] The relationship curve storage unit is used to store the relationship curve between the thermal transmittance coefficient and temperature of the current all-solid-state temperature sensing device.

[0018] The real-time transmittance calculation unit is used to calculate the ratio of the light power detected by the first photodetector and the second photodetector as the real-time transmittance.

[0019] The real-time thermal transmittance coefficient calculation unit is used to calculate the real-time thermal transmittance coefficient based on the real-time transmittance according to the following formula:

[0020]

[0021] In the formula, k represents the real-time thermal transmittance coefficient, S represents the real-time transmittance, and T represents the temperature;

[0022] The real-time temperature calculation unit is used to substitute the real-time heat transmission coefficient into the relationship curve between the heat transmission coefficient and temperature to find the real-time temperature.

[0023] Furthermore, the relationship curve between the thermal transmittance coefficient and temperature is obtained in the following manner:

[0024] Place the fiber microcavity in the heating device and set the heating temperature to any room temperature value;

[0025] At the current room temperature, the laser is set to scan at different wavelengths. Based on the optical power detected by the first and second photodetectors, the transmittance at different wavelengths at the current room temperature is calculated, that is, the transmission spectrum at the current room temperature.

[0026] By differentiating the transmission spectrum at room temperature, the relationship between transmittance and wavelength is obtained.

[0027] The heating temperature of the heating device is set to different values ​​to obtain the transmission spectrum at different temperature values. The center wavelength of the transmission spectrum is extracted and the relationship between the center wavelength and temperature change is established.

[0028] By multiplying the relationship between transmittance and wavelength, the relationship between center wavelength and temperature change, and the negative first power of transmittance, we obtain the curve showing the relationship between thermal transmittance coefficient and temperature.

[0029] Compared with the prior art, the beneficial effects of this invention are:

[0030] (1) The present invention uses an optical microcavity formed by a first fiber concave mirror coated with a high-reflection film and a second fiber concave mirror to realize temperature sensing. Compared with the optical microcavity of the prior art, the present invention has better interference effect, higher quality and higher sensitivity.

[0031] (2) In the temperature calculation, the present invention obtains the real-time temperature based on the measured transmittance and the relationship between transmittance, thermal transmission coefficient and temperature, without scanning all wavelengths, and has high real-time performance; in addition, the present invention utilizes the high sensitivity of thermal transmission coefficient to temperature changes to achieve effective amplification of small temperature changes, further improving sensitivity.

[0032] (3) The device of the present invention is simple, easy to integrate, low in cost, small in size and has a large dynamic range, and has better commercial value compared with existing high-sensitivity temperature sensors;

[0033] (4) The detection method is simple; it can be detected using a photoelectric detector and a computer.

[0034] (5) The system materials are simple and easy to obtain, and the system is easy to implement. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of the all-solid-state temperature sensing device based on a high-reflectivity optical film on a concave surface of an optical fiber provided in an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of the all-solid-state temperature sensing system based on a high-reflectivity optical film on a concave surface of an optical fiber, provided in an embodiment of the present invention.

[0037] Figure 3 This is a schematic diagram showing the placement of the heating device;

[0038] Figure 4 This is a graph showing the relationship between the center wavelength of the transmission spectrum and temperature in this invention;

[0039] Figure 5 This is a graph showing the sensitivity of an all-solid-state temperature sensing system based on a high-reflectivity optical film on a concave surface of an optical fiber as a function of frequency, provided by the present invention.

[0040] Figure 6 This is a graph showing the relationship between the thermal transmittance coefficient and temperature of this invention;

[0041] Figure 7This is a graph showing the sensitivity of another all-solid-state temperature sensing system based on a high-reflectivity optical film on a concave surface of an optical fiber, provided by the present invention, as a function of frequency. Detailed Implementation

[0042] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0043] Example 1

[0044] This invention provides an all-solid-state temperature sensing device based on a high-reflectivity optical film on a concave surface of an optical fiber, such as... Figure 1 As shown, it includes a laser 1, an optical fiber attenuator 2, an optical fiber coupler 3, an optical fiber microcavity (composed of a first optical fiber concave mirror 4 and a second optical fiber concave mirror 5, with a solid thermal expansion material 6, such as ultraviolet glue, filling the space between the first optical fiber concave mirror 4 and the second optical fiber concave mirror 5), a first photodetector 7, and a second photodetector 8.

[0045] Laser 1, fiber optic attenuator 2, and fiber optic coupler 3 form region I, enabling laser modulation. Laser 1 is a tunable continuous-wave laser, used to emit continuous laser light with a scanning range of 1500nm-1600nm. The beam power is adjusted to a suitable level by fiber optic attenuator 2. Subsequently, the beam enters fiber optic coupler 3, which splits the incident light into a first beam and a second beam in a 90:10 ratio. 90% of the first beam enters the fiber microcavity, and 10% of the second beam is used for detection.

[0046] Region II is a fiber optic microcavity, specifically an FP cavity, composed of a first concave fiber mirror 4 and a second concave fiber mirror 5. The first and second concave fiber mirrors 4 and 5 are formed by depositing a high-reflectivity optical film after the concave surface of the fiber is ablated using a CO2 laser. The high-reflectivity optical film is a 99.9% reflectivity dielectric film. The first concave fiber mirror 5 is connected to a fiber coupler 3 via an optical fiber, and the second concave fiber mirror 5 is connected to a first photodetector 7 via an optical fiber. In this embodiment, the cavity length of the fiber optic microcavity is 16 μm, the precision F-value is 2730, and the quality factor Q-value is 154918. The fiber optic microcavity is filled and encapsulated with a solid thermal expansion material 6. The solid thermal expansion material 6 filling the fiber optic microcavity has high thermal expansion properties. When the ambient temperature changes, the thermal deformation of the solid thermal expansion material 6 causes changes in transmittance and transmission spectrum. The temperature can be determined based on the relationship between transmittance or the center wavelength of the transmission spectrum and temperature.

[0047] The first photodetector 7 and the second photodetector 8 constitute region III, which is used to receive and process output signals. Temperature is calculated based on the power of the optical signals detected by the first photodetector 7 and the second photodetector 8.

[0048] The optical microcavity of this invention is composed of a first fiber concave mirror 4 and a second fiber concave mirror 5. Compared with the optical microcavities of the prior art, it has better interference effect, higher quality, and higher sensitivity.

[0049] Example 2

[0050] This invention provides an all-solid-state temperature sensing system based on a high-reflectivity optical film on a concave surface of an optical fiber, such as... Figure 2 As shown, the device includes an all-solid-state temperature sensing device and a temperature calculation module as described in Embodiment 1. The temperature calculation module is used to calculate the transmission spectrum of the fiber microcavity based on the optical power detected by the first and second photodetectors when the laser scans within a preset wavelength range. The center wavelength of the transmission spectrum is then substituted into a pre-stored curve showing the relationship between the center wavelength of the transmission spectrum and temperature to calculate the current real-time temperature.

[0051] Specifically, the temperature calculation module includes:

[0052] The relationship curve storage unit is used to store the relationship curve between the center wavelength of the transmission spectrum of the current all-solid-state temperature sensing device and the temperature.

[0053] The real-time transmission spectrum calculation unit is used to obtain the optical power detected by the first photodetector and the second photodetector when the laser scans within a preset wavelength range, calculate the ratio of the optical power detected by the first photodetector and the second photodetector at each wavelength, and use it as the transmittance at each wavelength to form a transmission spectrum.

[0054] The real-time center wavelength calculation unit obtains the wavelength where the transmittance peak is located in the transmission spectrum, and uses it as the real-time center wavelength of the transmission spectrum.

[0055] The real-time temperature calculation unit is used to substitute the center wavelength of the transmission spectrum into the relationship curve between the center wavelength of the transmission spectrum and temperature to find the real-time temperature.

[0056] The relationship curve between the center wavelength of the transmission spectrum and temperature can be obtained by placing a heating device 9 under the fiber optic microcavity, such as... Figure 3 As shown, the heating temperature is set to any value, the laser wavelength is scanned, and the transmission spectrum at that temperature is obtained. The center wavelength of the transmission spectrum resonator is extracted by the Lorentz fitting function. Then, the heating temperature is set to different values ​​to obtain the center wavelength of the transmission spectrum under different conditions, and the relationship between the center wavelength drift and temperature change is established. Figure 4 This describes the variation of the center wavelength of the transmission spectrum of an optical fiber FP microcavity with the ambient temperature. Figure 4 The sensor exhibits a dynamic range of 22℃-27℃, where the center wavelength of the transmission spectrum shifts to longer wavelengths as the ambient temperature increases. Furthermore, it demonstrates excellent linearity, achieving a response of 0.45 nm / ℃. Figure 5This demonstrates the sensitivity of a temperature sensor obtained by utilizing the relationship between the center wavelength of the transmission spectrum and temperature. Specifically, the ambient temperature around the fiber optic FP microcavity was fixed at 24°C, and the change in the center wavelength of the transmission spectrum over 1 second was measured. The sensitivity of the temperature sensor was then calculated using the power spectral density method. The results show that this invention achieves a sensitivity of 1 μkHz. -1 / 2 The temperature sensor measured using this method has the advantages of a large dynamic range and high sensitivity.

[0057] Example 3

[0058] This invention provides an all-solid-state temperature sensing system based on a high-reflectivity optical film on a concave surface of an optical fiber, such as... Figure 2 As shown, the device includes an all-solid-state temperature sensing device and a temperature calculation module as described in Embodiment 1. The temperature calculation module is used to calculate the real-time transmittance of the fiber microcavity based on the optical power detected by the first and second photodetectors, calculate the real-time thermal transmission coefficient based on the real-time transmittance, and substitute the real-time thermal transmission coefficient into the thermal transmission coefficient versus temperature curve to calculate the current real-time temperature.

[0059] Specifically, the temperature calculation module includes:

[0060] The relationship curve storage unit is used to store the relationship curve between the thermal transmittance coefficient and temperature of the current all-solid-state temperature sensing device.

[0061] The real-time transmittance calculation unit is used to calculate the ratio of the light power detected by the first photodetector and the second photodetector as the real-time transmittance.

[0062] The real-time thermal transmittance coefficient calculation unit is used to calculate the real-time thermal transmittance coefficient based on the real-time transmittance according to the following formula:

[0063]

[0064] In the formula, k represents the real-time thermal transmittance coefficient, S represents the real-time transmittance, and T represents the temperature;

[0065] The real-time temperature calculation unit is used to substitute the real-time heat transmission coefficient into the relationship curve between the heat transmission coefficient and temperature to find the real-time temperature.

[0066] The relationship curve between the thermal transmittance coefficient and temperature is obtained in the following way:

[0067] The fiber microcavity is placed in the heating device 9, and the heating temperature is set to any room temperature value, such as 22℃.

[0068] At the current room temperature, the laser is set to scan at different wavelengths (1500nm-1600nm). Based on the optical power detected by the first and second photodetectors, the transmittance S at different wavelengths λ at the current room temperature is calculated, which is the transmission spectrum at the current room temperature.

[0069] Differentiating the transmission spectrum at room temperature yields the relationship between transmittance S and wavelength λ.

[0070] The heating temperature of heating device 9 is set to different values ​​(e.g., from 22°C to 27°C) to obtain transmission spectra at different temperature values. The peak values ​​of the transmission spectra are fitted using a Lorentz fitting function to extract the center wavelength of the transmission spectrum, and the relationship between the center wavelength λ and the temperature T is established.

[0071] Multiply the relationship between transmittance and wavelength, the relationship between center wavelength and temperature change, and the negative first power of transmittance, i.e. The relationship curve between the thermal transmittance coefficient k and temperature T was obtained.

[0072] In this embodiment, the relationship curve between the thermal transmittance coefficient k and the temperature T is as follows: Figure 6 As shown, the maximum thermal transmission coefficient k max >50K -1 To determine the sensitivity of the sensor, the transmittance was measured over 1 second at a fixed wavelength and temperature at the point of maximum transmittance. The temperature fluctuation at this point was then represented using a power spectral density calculation method, yielding a sensitivity <1nk Hz. -1 / 2 ,like Figure 7 As shown, the temperature sensing device of the present invention has extremely high sensitivity.

[0073] It should be noted that in this paper, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0074] It should be understood that the embodiments and descriptions above are only the principles, main features and advantages of the present invention. Various changes and modifications can be made to the present invention without departing from the spirit and scope of the invention, and all such changes and modifications fall within the protection scope of the present invention.

Claims

1. A fully solid-state temperature sensing system based on a high-reflectivity optical film on a concave surface of an optical fiber, characterized in that, The system includes an all-solid-state temperature sensing device and a temperature calculation module. The all-solid-state temperature sensing device comprises a laser, an optical fiber attenuator, an optical fiber microcavity, an optical fiber coupler, a first photodetector, and a second photodetector. The optical fiber microcavity is composed of a first concave optical fiber mirror and a second concave optical fiber mirror. Both the first and second concave optical fiber mirrors are formed by fabricating concave surfaces on the end faces of optical fibers and then coating them with a high-reflectivity optical film. The concave surfaces of the first and second concave optical fiber mirrors face each other, and the space between the first and second concave optical fiber mirrors is filled with a solid thermal expansion material. The laser emitted by the laser enters the optical fiber coupler through the optical fiber attenuator. The optical fiber coupler splits the laser beam into a first beam and a second beam. The first beam enters the first photodetector through the optical fiber microcavity, and the second beam directly enters the second photodetector. The temperature calculation module is used to calculate the transmission spectrum of the optical fiber microcavity based on the optical power detected by the first and second photodetectors when the laser scans within a preset wavelength range. The center wavelength of the transmission spectrum is substituted into a pre-stored curve showing the relationship between the center wavelength of the transmission spectrum and temperature to calculate the current real-time temperature. The temperature calculation module specifically includes: The relationship curve storage unit is used to store the relationship curve between the center wavelength of the transmission spectrum of the current all-solid-state temperature sensing device and the temperature. The real-time transmission spectrum calculation unit is used to obtain the optical power detected by the first photodetector and the second photodetector when the laser scans within a preset wavelength range, calculate the ratio of the optical power detected by the first photodetector and the second photodetector at each wavelength, and use it as the transmittance at each wavelength to form a transmission spectrum. The real-time center wavelength calculation unit obtains the wavelength where the transmittance peak is located in the transmission spectrum, and uses it as the real-time center wavelength of the transmission spectrum. The real-time temperature calculation unit is used to substitute the center wavelength of the transmission spectrum into the relationship curve between the center wavelength of the transmission spectrum and temperature to find the real-time temperature.

2. The system according to claim 1, characterized in that: The fiber coupler splits the laser into a first beam and a second beam with a splitting ratio of 90:

10.

3. The system according to claim 1, characterized in that: The fiber optic microcavity is a Fabry-Pérot (FP) cavity.

4. The system according to claim 1, characterized in that: The first fiber concave mirror is connected to the fiber coupler via an optical fiber, and the second fiber concave mirror is connected to the first photodetector via an optical fiber.

5. The system according to claim 1, characterized in that: The high-reflectivity optical film is a dielectric film with a reflectivity of 99.9%.

6. A fully solid-state temperature sensing system based on a high-reflectivity optical film on a concave fiber, characterized in that, The system includes an all-solid-state temperature sensing device and a temperature calculation module. The all-solid-state temperature sensing device comprises a laser, an optical fiber attenuator, an optical fiber microcavity, an optical fiber coupler, a first photodetector, and a second photodetector. The optical fiber microcavity is composed of a first concave optical fiber mirror and a second concave optical fiber mirror. Both the first and second concave optical fiber mirrors are formed by fabricating concave surfaces on the end faces of optical fibers and then coating them with high-reflectivity optical films. The concave surfaces of the first and second concave optical fiber mirrors face each other, and the space between the first and second concave optical fiber mirrors is filled with a solid thermal expansion material. The laser emitted by the laser enters the optical fiber coupler through the optical fiber attenuator. The optical fiber coupler splits the laser beam into a first beam and a second beam. The first beam enters the first photodetector through the optical fiber microcavity, and the second beam directly enters the second photodetector. The temperature calculation module is used to calculate the real-time transmittance of the optical fiber microcavity based on the optical power detected by the first and second photodetectors, calculate the real-time thermal transmission coefficient based on the real-time transmittance, and substitute the real-time thermal transmission coefficient into the thermal transmission coefficient versus temperature curve to calculate the current real-time temperature. The temperature calculation module specifically includes: The relationship curve storage unit is used to store the relationship curve between the thermal transmittance coefficient and temperature of the current all-solid-state temperature sensing device. The real-time transmittance calculation unit is used to calculate the ratio of the light power detected by the first photodetector and the second photodetector as the real-time transmittance. The real-time thermal transmittance coefficient calculation unit is used to calculate the real-time thermal transmittance coefficient based on the real-time transmittance according to the following formula: , In the formula, Indicates the real-time thermal transmittance coefficient. This represents the real-time transmittance, and T represents the temperature. The real-time temperature calculation unit is used to substitute the real-time heat transmission coefficient into the relationship curve between the heat transmission coefficient and temperature to find the real-time temperature.

7. The all-solid-state temperature sensing system based on a high-reflectivity optical film on a concave fiber optic surface according to claim 6, characterized in that: The relationship curve between the thermal transmittance coefficient and temperature was obtained in the following way: Place the fiber microcavity in the heating device and set the heating temperature to any room temperature value; At the current room temperature, the laser is set to scan at different wavelengths. Based on the optical power detected by the first and second photodetectors, the transmittance at different wavelengths at the current room temperature is calculated, that is, the transmission spectrum at the current room temperature. By differentiating the transmission spectrum at room temperature, the relationship between transmittance and wavelength is obtained. The heating temperature of the heating device is set to different values ​​to obtain the transmission spectrum at different temperature values. The center wavelength of the transmission spectrum is extracted and the relationship between the center wavelength and temperature change is established. By multiplying the relationship between transmittance and wavelength, the relationship between center wavelength and temperature change, and the negative first power of transmittance, we obtain the curve showing the relationship between thermal transmittance coefficient and temperature.

Images