Integrated distributed Raman temperature sensing optical device

Abstract

The invention provides an integrated distributed Raman temperature sensing optical device. A light source unit, an optical collimation isolation unit, a Raman scattering light separation unit and a tail fiber connector unit which are sequentially and optically connected along an optical path are arranged in a packaging shell of the distributed Raman temperature sensing optical device; and a photoelectric detection analysis unit electrically connected with the Raman scattering light separation unit is also arranged in the packaging shell. According to the distributed Raman temperature sensing optical device, the light source unit, the optical collimation isolation unit, the Raman scattering light separation unit, the tail fiber connector unit and the photoelectric detection analysis unit are integrated in the same packaging shell, and free space light transmission is adopted to replace traditional optical fiber connection. Therefore, the space occupied by the device is greatly reduced, and the function expansion is feasible, so that the number of discrete devices and connection nodes are reduced, the reliability and stability of system operation are remarkably improved, and the actual application requirements of large infrastructure temperature monitoring on the miniaturized and high-reliability distributed Raman temperature sensing device are finally met.

Description

Technical Field

[0001] This invention relates to the field of distributed optical fiber sensing technology, and more particularly to an integrated distributed Raman temperature sensing optical device. Background Technology

[0002] With my country's rapid economic development, the total amount of large-scale infrastructure construction has exceeded that of all other countries combined, making its health monitoring a hot topic of research and social concern. Distributed Optical Fiber Sensing (DOFS) technology uses optical fiber as the signal transmission medium and sensing unit. By detecting changes in parameters such as the intensity, phase, and polarization state of the optical signal in the fiber under the influence of an external field, it achieves continuous distributed measurement of external parameters along the fiber. With this core advantage, it has become the most ideal non-destructive health monitoring technology for large-scale facilities in many fields such as energy, power, aerospace, communications, transportation, and security.

[0003] Against this backdrop, an increasing number of researchers and companies are entering the field of distributed fiber optic sensing, and the commercial and social value of this technology is becoming increasingly prominent, with its application and promotion gradually accelerating. However, due to the complexity of the working mechanism, technical solutions, and application environment involved in distributed fiber optic sensing, its research and application face many challenges. Crucially, early domestic research was mainly led by universities, focusing primarily on technological exploration and implementation. This resulted in commercialized equipment retaining a significant amount of research attributes, generally exhibiting problems such as large and cumbersome structures, rudimentary operating interfaces, and insufficient intelligence.

[0004] The basic structure of a traditional distributed fiber optic Raman temperature measurement system is as follows: Figure 1 As shown, the core components include five main categories: pulsed tunable lasers, optical circulators (OC), wavelength division multiplexing couplers (WDM), avalanche photodiodes (APDs) for detecting Stokes and anti-Stokes light, fiber optic under test (FUT), and data acquisition and processing modules. These components must be combined into a complete system to function, and require a driver board and demodulation circuit board to form a terminal device with actual temperature measurement capabilities. This structural design directly results in the current distributed fiber optic temperature measurement equipment being bulky, having a large number of optical components, and complex circuit systems. Furthermore, the increased number of optoelectronic components significantly increases the risk of failure; the failure of any single component can paralyze the entire device, severely impacting actual temperature measurement use, especially in scenarios such as fire detection, where equipment failure could lead to major safety accidents. Summary of the Invention

[0005] The purpose of this invention is to provide an integrated distributed Raman temperature sensing optical device to solve the technical problems of low integration, large size, complex devices and circuits leading to high failure risk and insufficient stability in existing distributed fiber Raman temperature measurement devices.

[0006] To address the aforementioned technical problems, this invention provides an integrated distributed Raman temperature sensing optical device, comprising a package housing, within which are arranged a light source unit, an optical collimation and isolation unit, a Raman scattering light separation unit, and a fiber optic connector unit, sequentially connected along the optical path; the package housing also includes a photoelectric detection and analysis unit, which is electrically connected to the Raman scattering light separation unit. The optical collimation and isolation unit is used to focus, redirect, and collimate the laser output from the light source unit, and suppress stray light interference; the Raman scattering light separation unit is used to separate the backscattered light generated when the laser is transmitted in the optical fiber under test into Raman-Stokes light and Raman-anti-Stokes light; the pigtail connector unit is used to connect the optical fiber under test and realize the precise coupling between the laser and the pigtail; the photoelectric detection and analysis unit is used to detect the optical power of the Raman-Stokes light and Raman-anti-Stokes light respectively and convert them into electrical signals, and then obtain the temperature value of the optical fiber under test based on the correlation between the electrical signal and temperature.

[0007] Preferably, the light source unit includes a semiconductor laser, and the optical collimation and isolation unit includes a lens, a first reflecting mirror, a collimator, and an isolator that are sequentially connected along the optical path; The lens is used to focus the laser output from the semiconductor laser; the first reflecting mirror is used to change the propagation direction of the laser after it has been focused by the lens, thereby turning the optical path; the collimator is used to collimate the laser after it has been turned by the first reflecting mirror, and output a parallel beam; the isolator is used to realize the unidirectional transmission of the collimated laser and suppress back stray light and echo interference.

[0008] Preferably, the Raman scattering light separation unit includes a second mirror and a third mirror that are sequentially connected along the optical path. The side of the second mirror closest to the isolator is coated with an anti-reflection film, and the side of the third mirror closest to the second mirror is coated with an anti-reflection film.

[0009] Preferably, the antireflective film is made of silicon dioxide or magnesium fluoride, which is used to allow laser and backscattered light to pass through without loss.

[0010] Preferably, the side of the second mirror closest to the third mirror is coated with a first wavelength selective reflective film; the first wavelength selective reflective film has a reflectivity of ≥99% only for Raman Stokes light and a transmittance of ≥99% for Raman anti-Stokes light.

[0011] Preferably, the side of the third reflector closest to the fiber optic connector unit is coated with a second wavelength selective reflective film; the second wavelength selective reflective film has a reflectivity of ≥99% for Raman anti-Stokes light only, and a transmittance of ≥99% for Raman anti-Stokes light.

[0012] Preferably, the center reflection wavelength of the first wavelength selective reflective film deviates from the characteristic wavelength of Raman Stokes light by ≤ ±5 nm, and the center reflection wavelength of the second wavelength selective reflective film deviates from the characteristic wavelength of Raman anti-Stokes light by ≤ ±5 nm.

[0013] Preferably, the photoelectric detection and analysis module includes a first photodetector and a second photodetector. The first photodetector is used to detect the first optical power of the Raman Stokes light reflected by the second reflector, and the second photodetector is used to detect the second optical power of the Raman anti-Stokes light reflected by the third reflector.

[0014] Preferably, the photoelectric detection and analysis unit further includes a signal processing unit electrically connected to the first photodetector and the second photodetector respectively. The signal processing unit is used to determine the temperature value of the sensing fiber under test based on the ratio of the first optical power to the second optical power and the preset quantitative relationship between the Raman scattered light power and the temperature.

[0015] Preferably, the pigtail connector unit includes a connector, an end face, and a pigtail connected in sequence; the connector is an optical fiber connector, used to form a stable assembly with the encapsulation housing through threaded or snap-fit ​​connection, while ensuring that the beam is accurately aligned with the core of the pigtail; the end face is an optical fiber ferrule end face that has undergone polishing process, used to optimize optical signal transmission efficiency and suppress reflection noise; one end of the pigtail is fixedly connected to the connector, and the core of the pigtail is coaxially aligned with the center of the end face, used to achieve offset-free coupling between the beam and the pigtail.

[0016] The beneficial effects of this invention are as follows: Unlike existing technologies, this invention provides an integrated distributed Raman temperature sensing optical device. The device's package contains a light source unit, an optical collimation and isolation unit, a Raman scattering light separation unit, and a fiber optic connector unit, sequentially connected along the optical path. The package also contains a photoelectric detection and analysis unit electrically connected to the Raman scattering light separation unit. By integrating the light source unit, optical collimation and isolation unit, Raman scattering light separation unit, fiber optic connector unit, and photoelectric detection and analysis unit into a single package, and using free-space optical transmission instead of traditional fiber optic connections, this significantly reduces the device's space requirements and makes functional expansion feasible. This reduces the number of discrete components and connection nodes, lowers the impact of single-component failures on the overall system, and significantly improves the reliability and stability of the system. Ultimately, it meets the practical application requirements of miniaturized, highly reliable distributed Raman temperature sensing devices for large-scale infrastructure temperature monitoring. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a typical distributed fiber optic temperature measurement system in the prior art; Figure 2 This is a schematic diagram of light propagation in an optical fiber. Figure 3 A schematic diagram illustrating the types of optical fiber backscattering; Figure 4 A schematic diagram of the integrated distributed Raman temperature sensing optical device provided in Example 1; In the attached figures: 101—semiconductor laser; 102—lens; 103—first reflecting mirror; 104—collimator; 105—isolator; 106—second reflecting mirror; 107—third reflecting mirror; 108—connector; 109—end face; 110—fiber optic pigtail; 111—first photodetector; 112—second photodetector. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] When light propagates in an optical fiber, it continuously scatters along the fiber (e.g., Figure 1 As shown: core (fiber core); incident light (incident light); cladding (cladding); back scattered light (backscattered light); forward propagating light (forward propagating light). Due to the confinement of light waves by the optical fiber, scattered light only exhibits two propagation directions: forward and back. However, environmental disturbances around the fiber can cause changes in key parameters of the fiber core (such as length, diameter, and refractive index). These parameter changes, in turn, modulate the scattered light, leading to alterations in its intensity, phase, frequency, and other characteristics. Based on this characteristic, by spatially demodulating the scattered light signal along the optical fiber, precise monitoring of environmental disturbances in equally spaced blocks on the fiber can be achieved, effectively replacing tens of thousands of point sensors. This also lays the foundation for the development of distributed optical fiber temperature monitoring technology.

[0020] To achieve accurate temperature monitoring, it is necessary to first understand the differences in characteristics between various types of scattered light. Based on whether photons undergo elastic collisions with medium particles, scattered light can be divided into elastic and inelastic scattered light. Rayleigh scattering is an elastic scattering method, where the frequency of the scattered light is exactly the same as the incident light frequency; Brillouin scattering and Raman scattering, on the other hand, are inelastic scattering methods, where the frequency of the scattered light differs from the incident light frequency. In inelastic scattered light, light with a frequency lower than the incident light is called Stokes light, and light with a higher frequency is called anti-Stokes light (e.g., ...). Figure 2 As shown in the figure, the characteristics of these two types of scattered light directly determine their applicability in temperature monitoring.

[0021] From the perspective of scattering principles and temperature correlation, the application value of different scattered light sources varies significantly: Rayleigh scattering is caused by random fluctuations in the spatial distribution of particles in the fiber medium, leading to random changes in the fiber polarization characteristics. Its intensity has extremely low correlation with temperature, making it unsuitable for temperature monitoring. Brillouin scattering results from the interaction between the incident light and the acoustic field formed by the thermal motion of particles in the medium, while Raman scattering is caused by the periodic time modulation of the induced electric dipole moment of molecules due to the relative motion of particles within the medium. Both are directly related to the motion of particles within the medium, therefore the intensity of the scattered light changes with the temperature of the medium, providing the basic conditions for temperature monitoring. However, it should be noted that Brillouin scattered light is simultaneously affected by strain. If used for temperature monitoring, additional decoupling of temperature and strain is required. Furthermore, its frequency shift is only tens of GHz, very close to the incident light frequency, significantly increasing the complexity of the optical path design and limiting its applicability.

[0022] Considering the differences in the characteristics of the scattered light, Raman scattering is the optimal choice for temperature monitoring. Therefore, this application selects to simultaneously demodulate the anti-Stokes light signal intensity and the Stokes light signal intensity of the Raman scattered light in the optical fiber, and uses the ratio of the two to offset interference factors such as optical fiber loss, so as to achieve efficient and accurate monitoring of changes in external ambient temperature.

[0023] However, existing distributed fiber optic Raman temperature measurement systems based on the aforementioned Raman temperature measurement principle generally suffer from problems such as a large variety of optical devices, dispersed structural designs, and reliance on traditional optical fiber connections. This results in a complex, bulky, and large-scale system that not only occupies more installation space but also increases the probability of failure due to the large number of devices and complex connection nodes, thus affecting system stability. To address this core pain point, this application proposes an integrated optical device design based on a free-space optical transmission scheme. This integrated optical device consists of a laser chip, lens, collimator, mirror, isolator, avalanche photodiode (APD) chip, connector, end face, and pigtail. All of these components are integrated and packaged in a small-sized housing, ultimately forming a miniaturized, highly reliable integrated optical device that effectively solves the shortcomings of traditional systems.

[0024] The technical solution of the present invention will now be further described with reference to specific embodiments.

[0025] Example 1: Please see Figure 4 , Figure 4 The diagram below shows the structure of the integrated distributed Raman temperature sensing optical device provided in Example 1. The integrated distributed Raman temperature sensing optical device includes a package housing, and the package housing contains a light source unit, an optical collimation isolation unit, a Raman scattering light separation unit, and a pigtail connector unit that are sequentially connected along the optical path. The package housing also contains a photoelectric detection and analysis unit, which is electrically connected to the Raman scattering light separation unit. The optical collimation and isolation unit is used to focus, redirect, and collimate the laser output from the light source unit and suppress stray light interference; the Raman scattering light separation unit is used to separate the backscattered light generated when the laser is transmitted in the optical fiber under test into Raman-Stokes light and Raman-anti-Stokes light; the pigtail connector unit is used to connect the optical fiber under test and realize the precise coupling between the laser and the pigtail 110; the photoelectric detection and analysis unit is used to detect the optical power of the Raman-Stokes light and Raman-anti-Stokes light respectively and convert them into electrical signals, and then obtain the temperature value of the optical fiber under test based on the correlation between the electrical signal and temperature.

[0026] Specifically, this integrated distributed Raman temperature sensing optical device integrates the light source unit, optical collimation and isolation unit, Raman scattering light separation unit, fiber optic connector unit, and photoelectric detection and analysis unit into the same package, achieving optical path integration and miniaturization, and significantly reducing the device size. Simultaneously, the focusing, collimation, and stray light suppression effects of the optical collimation and isolation unit, combined with the precise coupling function of the fiber optic connector unit, improve the accuracy of optical signal transmission and coupling, ensuring the accuracy of backscattered light separation. The photoelectric detection and analysis unit accurately detects and converts the two types of Raman scattering light, ensuring the reliability of temperature monitoring. The overall integrated design also reduces discrete components and connection nodes, lowering the probability of failure and significantly improving system stability, effectively meeting the miniaturization and high reliability application requirements of distributed Raman temperature sensing.

[0027] In Embodiment 1, the light source unit includes a semiconductor laser 101, and the optical collimation and isolation unit includes a lens 102, a first reflector 103, a collimator 104, and an isolator 105 that are sequentially connected along the optical path.

[0028] Specifically, the semiconductor laser 101 is used to generate the pulsed laser required for distributed Raman temperature sensing, serving as the core light source of the entire sensing system and providing basic optical energy for subsequent optical signal transmission, scattering, and temperature detection. The lens 102 is used to focus the laser output from the semiconductor laser 101, achieving beam convergence and providing a suitable beam shape for subsequent first reflector 103 steering and collimator 104 calibration, ensuring optical path transmission efficiency. The first reflector 103 is used to change the propagation direction of the laser after being focused by the lens 102, achieving optical path angle deflection and accurately guiding the converged laser to the collimator 104, optimizing the optical path design in conjunction with the spatial layout of the integrated housing. The collimating mirror is used to collimate the laser after being steered by the first reflector 103, outputting a parallel beam, and simultaneously completing beam calibration and coupling, ensuring that the laser intensity and emission angle meet the requirements of the sensing system, and ensuring stable transmission of the laser in the subsequent optical path and the optical fiber under test.

[0029] Specifically, isolator 105 is used to achieve unidirectional transmission of collimated laser light, isolate backscattered light such as Rayleigh scattering, Brillouin scattering, and Raman scattering, and prevent backscattered light from causing negative effects such as power fluctuations, wavelength drift, and increased relative intensity noise (RIN) on semiconductor laser 101. At the same time, it prevents the high-power light energy reflected from burning out the chip of semiconductor laser 101, ensuring the long-term stable operation of semiconductor laser 101.

[0030] In Embodiment 1, the Raman scattering light separation unit includes a second reflector 106 and a third reflector 107 connected sequentially along the optical path. The second reflector 106 has an anti-reflection coating on the side of its mirror closest to the isolator 105, and the third reflector 107 has an anti-reflection coating on the side of its mirror closest to the second reflector 106. The anti-reflection coating is made of silicon dioxide or magnesium fluoride and is used to allow laser light and backscattered light to pass through without loss.

[0031] In Example 1, the side of the second reflector 106 closest to the third reflector 107 is coated with a first wavelength selective reflective film; the first wavelength selective reflective film has a reflectivity ≥99% only for Raman-Stokes light and a transmittance ≥99% for Raman-anti-Stokes light; the side of the third reflector 107 closest to the pigtail connector unit is coated with a second wavelength selective reflective film; the second wavelength selective reflective film has a reflectivity ≥99% only for Raman-anti-Stokes light and a transmittance ≥99% for Raman-anti-Stokes light.

[0032] Specifically, the above design achieves efficient and accurate separation of Raman-Stokes light and Raman-anti-Stokes light, ensuring both high reflection / transmission efficiency (minimal signal loss) for both types of target optical signals and avoiding crosstalk between the two types of optical signals, providing a high-purity and sufficient optical signal basis for the photoelectric detection and analysis unit to accurately detect the optical power of each signal.

[0033] In Example 1, the center reflection wavelength of the first wavelength selective reflective film deviates from the characteristic wavelength of Raman Stokes light by ≤ ±5 nm, and the center reflection wavelength of the second wavelength selective reflective film deviates from the characteristic wavelength of Raman anti-Stokes light by ≤ ±5 nm.

[0034] Specifically, the above design achieves precise matching between the two reflective films and the characteristic wavelengths of the two types of target Raman scattered light, ensuring that the reflectivity of the film layer for the corresponding wavelength light signal remains stable at a high value (≥99%), and the transmittance for the other type of wavelength light signal remains stable and meets the standard. This effectively avoids problems such as signal loss and crosstalk enhancement caused by wavelength deviation, and ensures the accuracy and efficiency of Raman Stokes light and Raman anti-Stokes light separation.

[0035] In Embodiment 1, the photoelectric detection and analysis module includes a first photodetector 111 and a second photodetector 112. The first photodetector 111 is used to detect the first optical power of the Raman Stokes light reflected by the second reflector 106, and the second photodetector 112 is used to detect the second optical power of the Raman anti-Stokes light reflected by the third reflector 107.

[0036] In Embodiment 1, the photoelectric detection and analysis unit further includes a signal processing unit that is electrically connected to the first photodetector 111 and the second photodetector 112 respectively. The signal processing unit is used to determine the temperature value of the sensing fiber under test based on the ratio of the first optical power to the second optical power and the preset quantitative relationship between the Raman scattered light power and the temperature.

[0037] Specifically, the photoelectric detection and analysis unit accurately detects the optical power of the separated Raman-Stokes light and Raman-anti-Stokes light through the first photodetector 111 and the second photodetector 112, respectively. Then, the signal processing unit calculates the temperature value based on the ratio of the two types of optical power and the preset quantitative relationship between Raman scattered light power and temperature. This not only achieves targeted and accurate detection of the two types of target optical signals, but also effectively offsets interference factors such as fiber loss and light intensity fluctuations through the ratio method, significantly improving the accuracy and anti-interference ability of temperature calculation, and ensuring the accuracy, stability and reliability of temperature measurement of the sensing fiber under test.

[0038] In Embodiment 1, the pigtail connector unit includes a connector 108, an end face 109, and a pigtail 110 connected in sequence. The connector 108 is an optical fiber connector, which is used to form a stable assembly with the encapsulation housing through threaded or snap-fit ​​connection, while ensuring that the beam is accurately aligned with the fiber core of the pigtail 110. The end face 109 is an optical fiber ferrule end face 109 that has undergone a polishing process, which is used to optimize the optical signal transmission efficiency and suppress reflection noise. One end of the pigtail 110 is fixedly connected to the connector 108, and the fiber core of the pigtail 110 is coaxially aligned with the center of the end face 109, which is used to achieve offset-free coupling between the beam and the pigtail 110.

[0039] Specifically, the pigtail connector unit uses an optical fiber connector to form a stable assembly with the encapsulation housing, while ensuring that the beam is accurately aligned with the pigtail 110 core. This not only ensures the stability of the module assembly but also avoids optical power loss caused by optical path misalignment. The fiber ferrule end face 109, which has been polished, effectively optimizes the optical signal transmission efficiency and suppresses reflection noise, ensuring that both forward laser and reverse Raman scattered light are free from stray light interference and can smoothly couple with the pigtail 110. In addition, the coaxial alignment design between the pigtail 110 core and the center of the end face 109 achieves offset-free and efficient coupling between the beam and the pigtail 110, ultimately forming a structurally stable and optically reliable free-space optical transmission module.

[0040] Further integration Figure 1 As can be seen, the specific working process of the integrated distributed Raman temperature sensing optical device provided in Example 1 is as follows: First, after the semiconductor laser 101 chip is powered on, it generates divergent laser light, which is first focused by the spherical lens 102 to form a concentrated single-beam light source. Subsequently, a single beam of light source is incident on the first reflector 103. By adjusting the deflection angle of the first reflector 103, the beam is precisely entered into the collimator 104 for collimation processing to improve beam stability and ensure accurate alignment of the subsequent optical path and back-end optical devices. Afterward, the collimated parallel beam enters the isolator 105. The isolator 105 mainly isolates stray light such as Rayleigh scattering light transmitted in reverse, to prevent high-power backscattered light from flowing back into the laser chip and to prevent it from affecting the output stability of the semiconductor laser 101 (such as power fluctuation, wavelength drift, increased RIN noise, etc.). After that, the beam of light after passing through isolator 105 continues to propagate forward, passing through second reflector 106 and third reflector 107 in sequence before reaching the front-end transmitting port; wherein, the side of second reflector 106 and third reflector 107 closest to isolator 105 (back end) is coated with anti-reflection film, which can reduce beam transmission loss and efficiently guide the laser into end face 109 and pigtail 110, and finally accurately inject it into the back end sensor fiber under test; The second reflector 106 and the third reflector 107 are respectively coated with a first wavelength selective reflective film and a second wavelength selective reflective film on the side (front end) near the pigtail 110. The two types of reflective film layers accurately guide the corresponding Raman scattered light to two avalanche photodiodes (APDs). Finally, after the two photodetectors receive the corresponding Raman-Stokes light and Raman-anti-Stokes light, they convert the light signal intensity into an electrical signal (photocurrent). The change in light intensity with temperature will synchronously cause the photocurrent to change. The signal processing unit calculates the temperature value of the sensing fiber under test by detecting the ratio of the light power corresponding to the two types of photocurrents and combining the preset quantitative relationship between Raman scattered light power and temperature, thus realizing distributed and accurate temperature monitoring.

[0041] In this application, the pre-defined quantitative relationship between Raman scattering light power and temperature is derived based on the Boltzmann distribution law. The ratio of Raman anti-Stokes light power to Stokes light power exhibits a negative exponential relationship with absolute temperature T. This relationship is derived from the Boltzmann distribution law: as temperature increases, the number of excited-state molecules increases, the anti-Stokes light power increases significantly, and the Stokes light power remains basically stable, leading to an exponential increase in their ratio; conversely, it decreases exponentially. This exponential relationship allows temperature changes to have a significant regulatory effect on the power ratio, providing a high-sensitivity basis for temperature measurement. Combined with the anti-interference characteristics of the ratio method, it ensures the accuracy and stability of temperature measurement.

[0042] In summary, unlike existing distributed Raman temperature sensing systems that rely on discrete components and fiber optic connections, resulting in bulky size, complex connection nodes, high failure risk, and limited functional expansion, this invention integrates the light source unit, optical collimation and isolation unit, Raman scattering light separation unit, pigtail connector unit, and photoelectric detection and analysis unit into a single housing. Furthermore, it replaces traditional fiber optic connections with free-space light transmission, significantly reducing the overall space occupied by the device and achieving device miniaturization. This effectively meets the stringent space requirements for large-scale infrastructure temperature monitoring (such as fire detection and other high-risk scenarios). By reducing the number of discrete components and fiber optic connection nodes, the probability of failures caused by dispersed component layout, loose connections, or aging is reduced. At the same time, it avoids additional interference such as transmission loss and coupling deviation caused by traditional fiber optic connections, ensuring the stability and accuracy of optical signal transmission. In addition, the space saved by the integrated design provides ample feasibility for adding additional sensing function modules and optimizing the hardware support related to temperature measurement algorithms. Ultimately, it significantly improves the operational reliability, environmental adaptability, and functional scalability of the entire sensing system, comprehensively solves the core pain points of existing technologies, and greatly enhances the practical value and industrialization potential of distributed Raman temperature sensing technology.

[0043] It should be noted that all the above embodiments belong to the same inventive concept, and the descriptions of each embodiment have different focuses. Where the description in a particular embodiment is not detailed, please refer to the description in other embodiments.

[0044] The above embodiments merely illustrate implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An integrated distributed Raman temperature sensing optical device, characterized in that, The device includes a packaging housing, within which are arranged a light source unit, an optical collimation and isolation unit, a Raman scattering light separation unit, and a fiber optic connector unit, which are sequentially connected along the optical path; the packaging housing also includes a photoelectric detection and analysis unit, which is electrically connected to the Raman scattering light separation unit. The optical collimation and isolation unit is used to focus, redirect, and collimate the laser output by the light source unit, and suppress stray light interference; the Raman scattering light separation unit is used to separate the backscattered light generated by the laser during transmission in the optical fiber under test into Raman-Stokes light and Raman-anti-Stokes light; the pigtail connector unit is used to connect the optical fiber under test and achieve precise coupling between the laser and the pigtail; the photoelectric detection and analysis unit is used to detect the optical power of the Raman-Stokes light and the Raman-anti-Stokes light respectively and convert them into electrical signals, and then obtain the temperature value of the optical fiber under test based on the correlation between the electrical signal and temperature.

2. The integrated distributed Raman temperature sensing optical device according to claim 1, characterized in that, The light source unit includes a semiconductor laser, and the optical collimation and isolation unit includes a lens, a first reflecting mirror, a collimator, and an isolator that are sequentially connected along the optical path. The lens is used to focus the laser output from the semiconductor laser; the first reflector is used to change the propagation direction of the laser after it has been focused by the lens, thereby achieving optical path redirection; the collimator is used to collimate the laser after it has been redirected by the first reflector, thereby outputting a parallel beam; and the isolator is used to achieve unidirectional transmission of the collimated laser and suppress back stray light and echo interference.

3. The integrated distributed Raman temperature sensing optical device according to claim 1, characterized in that, The Raman scattering light separation unit includes a second mirror and a third mirror that are sequentially connected along the optical path. The side of the second mirror closest to the isolator is coated with an anti-reflection film, and the side of the third mirror closest to the second mirror is coated with the same anti-reflection film.

4. The integrated distributed Raman temperature sensing optical device according to claim 3, characterized in that, The antireflective coating is made of silicon dioxide or magnesium fluoride and is used to allow the laser and the backscattered light to pass through without loss.

5. The integrated distributed Raman temperature sensing optical device according to claim 3, characterized in that, The second reflector has a first wavelength selective reflective film coated on the side of its surface closest to the third reflector; the first wavelength selective reflective film has a reflectivity of ≥99% only for the Raman Stokes light and a transmittance of ≥99% for the Raman anti-Stokes light.

6. The integrated distributed Raman temperature sensing optical device according to claim 5, characterized in that, The third reflector has a second wavelength selective reflective film coated on the side of the fiber optic connector unit closest to it. The second wavelength selective reflective film has a reflectivity of ≥99% for the Raman anti-Stokes light and a transmittance of ≥99% for the Raman anti-Stokes light.

7. The integrated distributed Raman temperature sensing optical device according to claim 6, characterized in that, The center reflection wavelength of the first wavelength selective reflective film deviates from the characteristic wavelength of the Raman Stokes light by ≤ ±5 nm, and the center reflection wavelength of the second wavelength selective reflective film deviates from the characteristic wavelength of the Raman anti-Stokes light by ≤ ±5 nm.

8. The integrated distributed Raman temperature sensing optical device according to claim 3, characterized in that, The photoelectric detection and analysis module includes a first photodetector and a second photodetector. The first photodetector is used to detect the first optical power of the Raman Stokes light reflected by the second reflector, and the second photodetector is used to detect the second optical power of the Raman anti-Stokes light reflected by the third reflector.

9. The integrated distributed Raman temperature sensing optical device according to claim 8, characterized in that, The photoelectric detection and analysis unit further includes a signal processing unit electrically connected to the first photodetector and the second photodetector respectively. The signal processing unit is used to determine the temperature value of the sensing fiber under test based on the ratio of the first optical power to the second optical power and a preset quantitative relationship between Raman scattered light power and temperature.

10. The integrated distributed Raman temperature sensing optical device according to claim 1, characterized in that, The pigtail connector unit includes a connector, an end face, and the pigtail connected in sequence. The connector is an optical fiber connector for secure assembly with the encapsulation housing via threaded or snap-fit ​​connections, while ensuring precise alignment of the light beam with the pigtail core. The end face is a polished optical fiber ferrule end face to optimize optical signal transmission efficiency and suppress reflection noise. One end of the pigtail is fixedly connected to the connector, and the pigtail core is coaxially aligned with the center of the end face to achieve offset-free coupling between the light beam and the pigtail.

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