Multi-parameter measurement optical fiber sensing device based on space division multiplexing technology

Abstract

The utility model relates to the technical field of optical fiber sensors, in particular to a multi-parameter measurement optical fiber sensing device based on a space division multiplexing technology, which comprises a plurality of lasers with different frequencies and a plurality of M-Z optical fiber sensors respectively connected with the lasers through a plurality of first single-mode optical fibers. The space division multiplexer is connected with the M-Z optical fiber sensors through optical fiber connectors, the output end of the space division multiplexer is connected with the spectrograph by welding a second multi-core optical fiber, the spectrograph is connected with the upper computer, and each M-Z optical fiber sensor is formed by sequentially aligning and welding an input single-mode optical fiber, a first multi-core optical fiber and an output single-mode optical fiber. The first multi-core optical fiber is provided with a cavity. According to the utility model, the integration level is high, the real-time performance and the accuracy of multi-parameter measurement can be improved, each component of the device adopts a modular design, components can be adjusted or replaced according to specific requirements, the maintainability and the upgradability of the whole device are improved, and the expansion or the part replacement of the device in the future is more convenient.

Description

Technical Field

[0001] The utility model relates to the technical field of optical fiber sensors, in particular to a multi-parameter measurement optical fiber sensing device based on space division multiplexing technology. Background Art

[0002] With the development of modern society, fiber optic sensing technology is widely used in industrial, scientific research, and defense applications. In particular, in fields requiring high-precision, multi-parameter monitoring, such as environmental monitoring, petrochemicals, aerospace, and smart grids, fiber optic sensors have gradually become an important sensing method due to their high sensitivity, strong resistance to electromagnetic interference, and long-distance transmission. Fiber optic sensing technology uses optical fiber to sense and measure environmental parameters. It uses optical fiber as a sensing medium and combines optical principles to detect changes in physical quantities such as temperature, stress, vibration, and pressure. These sensors are widely researched and applied due to their advantages, such as small size, light weight, resistance to electromagnetic interference, ease of integration, corrosion resistance, good biocompatibility, and remote monitoring capabilities.

[0003] A spatial division multiplexer (SDM) is a device commonly used in communication systems. It allows multiple signals to be transmitted simultaneously on the same transmission medium, and these signals are spatially separated. Therefore, it can improve the data transmission capacity and transmit data. By utilizing its ability to integrate multiple signals together, it also has great application prospects in multi-parameter measurement fiber optic sensing devices.

[0004] Currently, the demand for multi-parameter sensing is increasing in the field of sensing. However, most of the sensing fibers currently used are single-parameter measurement fiber optic sensors, such as those based on the Mach-Zehnder (MZ) interferometry principle. The Mach-Zehnder interferometry principle is a classic optical measurement method that uses the coherence and interference effects of light to accurately measure optical path differences, and is therefore widely used in fiber optic sensors. Fiber optic sensors based on this principle can sensitively detect small changes in the external environment (such as temperature, pressure, and refractive index changes) through interference effects. In recent years, fiber optic sensors based on Mach-Zehnder interferometry technology have been widely used in the field of precision measurement. However, traditional structures are mostly closed, with relatively indirect contact between the sensor and the measured environment and a relatively slow response speed.

[0005] To simultaneously measure multiple parameters, multiple fiber optic sensors are typically required. This not only complicates system wiring and reduces integration, but also takes up a lot of space and is costly. Furthermore, in complex environments, the deployment of multiple fibers increases the risk of interference, impacting system reliability and stability. Furthermore, signal demodulation makes it difficult to distinguish the impact of individual parameters. Utility Model Content

[0006] In view of the above problems, the present invention provides an optical fiber sensing device capable of measuring multiple parameters by using space division multiplexing technology.

[0007] The technical solution adopted by the utility model is: a multi-parameter measurement optical fiber sensing device based on space division multiplexing technology, comprising: a plurality of lasers of different frequencies; a plurality of MZ optical fiber sensors connected to the plurality of lasers respectively through a plurality of first single-mode optical fibers; a space division multiplexer connected to the plurality of MZ optical fiber sensors through optical fiber connectors; an output end of the space division multiplexer is connected to a spectrometer by fusing a second multi-core optical fiber; and the spectrometer is connected to a host computer;

[0008] The number of fiber cores of the space division multiplexer is the same as the number of fiber cores of the second multi-core optical fiber, the number of MZ optical fiber sensors, and the number of lasers;

[0009] The MZ optical fiber sensor is composed of an input single-mode optical fiber, a first multi-core optical fiber, and an output single-mode optical fiber, which are aligned and fused in sequence by a fusion splicer, and a cavity is set on the first multi-core optical fiber;

[0010] Furthermore, the cavity is a rectangular cavity with a length of 500-2000 μm and a depth not greater than the radius of the first multi-core optical fiber;

[0011] Furthermore, a sensitizing material is provided in the cavity;

[0012] Furthermore, the core of the space division multiplexer is composed of a plurality of second single-mode optical fibers, and the geometric arrangement thereof is the same as the core arrangement of the second multi-core optical fiber;

[0013] Furthermore, the plurality of second single-mode optical fibers are centrally symmetrically arranged;

[0014] Furthermore, the protective shell material of the space division multiplexer is polytetrafluoroethylene;

[0015] Furthermore, when the output end of the space division multiplexer is fused with the second multi-core optical fiber, the output end of the space division multiplexer needs to be tapered so that the core of the output end is 1-2 μm smaller than the core diameter of the second multi-core optical fiber.

[0016] The beneficial effects of the utility model are:

[0017] 1. Enhanced Multi-Parameter Measurement Capabilities: By incorporating space-division multiplexing technology, the device can simultaneously transmit and process signals from multiple sensors. Multiple single-mode optical fibers independently transmit laser signals of varying frequencies, enabling simultaneous measurement of multiple parameters. This design enables the device to monitor multiple physical or chemical parameters simultaneously, improving measurement efficiency and device applicability.

[0018] 2. High integration and space saving: By integrating the signals of multiple single-mode fibers into a single multi-core single-mode fiber through a space-division multiplexer, the number of fibers required is significantly reduced, thereby reducing the size of the device and the complexity of wiring. This can effectively save space and reduce installation difficulty and cost in scenarios requiring large-scale sensing, such as industrial environments and data centers.

[0019] 3. High-Precision Measurement: This device utilizes an open-cavity MZ fiber sensor based on the Mach-Zehnder interferometer principle, enabling precise optical path difference measurement. This interference phenomenon enables precise capture of subtle environmental changes (such as temperature, pressure, and refractive index), enhancing the sensor's sensitivity and accuracy. Furthermore, the cavity structure, etched using femtosecond technology, achieves even more precise dimensions, further enhancing the real-time and accuracy of measurements.

[0020] 4. Multi-band signal transmission: The device uses lasers of different frequencies to distinguish and transmit optical signals of different wavelengths. Each single-mode optical fiber transmits an independent optical signal, eliminating interference between signals and ensuring data reliability and accuracy. This design enables simultaneous transmission of multi-band signals without increasing complexity.

[0021] 5. Modular Design and Flexibility: The various components of the device (such as the laser, MZ interferometer, and space division multiplexer) adopt a modular design, allowing for adjustment or replacement of components based on specific needs. This design improves the maintainability and upgradeability of the device, making it easier to expand the device or replace components in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic structural diagram of a multi-parameter measurement optical fiber sensing device based on space division multiplexing technology in the present invention;

[0023] Figure 2 This is a schematic diagram of the structure of the MZ optical fiber sensor of the utility model;

[0024] Figure 3 This is a schematic diagram of the structure of the utility model multiplexer;

[0025] Among them: 1. Laser; 2. First single-mode optical fiber; 3. MZ optical fiber sensor; 4. Optical fiber connector; 5. Space division multiplexer; 6. Second multi-core optical fiber; 7. Spectrometer; 8. Input single-mode optical fiber; 9. First multi-core optical fiber; 10. Cavity; 11. Output single-mode optical fiber; 12. Cladding; 13. Second single-mode optical fiber; 14. Glass sleeve; 15. Host computer. DETAILED DESCRIPTION

[0026] The following is a further detailed description of the technical solution adopted by the present invention in conjunction with the accompanying drawings and embodiments. It should be noted that the following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0027] like Figure 1 As shown, the utility model provides a multi-parameter measurement optical fiber sensing device based on space division multiplexing technology, comprising: a laser 1, a first single-mode optical fiber 2, an MZ optical fiber sensor 3, an optical fiber connector 4, a space division multiplexer 5, a second multi-core optical fiber 6, a spectrometer 7 and a host computer 15;

[0028] The laser 1 is used to output a continuous laser signal and is connected to the input end of the MZ fiber optic sensor 3 through a first single-mode optical fiber 2. That is, the continuous laser signal output by the laser 1 is transmitted as input light to the MZ fiber optic sensor 3. The MZ fiber optic sensor 3 is an optical fiber sensor based on the Mach-Zehnder interferometer principle, which is used to detect a parameter to be measured and output interference light. For the measurement requirements of multiple parameters, the utility model uses lasers 1 with the same number and different frequencies as the parameters to be measured, respectively connected to the input ends of multiple MZ fiber optic sensors 3 through multiple single-mode optical fibers 2, that is, using multiple laser signals with different frequencies and multiple MZ fiber optic sensors 3 to achieve measurement of multiple parameters;

[0029] The output ends of multiple MZ fiber optic sensors 3 are connected to the input ends of the space division multiplexer 5 through the fiber optic connector 4. The number of fiber cores of the space division multiplexer 5 is the same as the number of MZ fiber optic sensors 3 set. As a fan-in device, it can couple the interference light signals output by multiple MZ fiber optic sensors 3. The output end of the space division multiplexer 5 is connected to the spectrometer 7 by fusing a second multi-core optical fiber 6 with the same number of fiber cores as it. The spectrometer 7 is used to detect and analyze the coupled interference light signal and convert it into spectral data. The spectrometer 7 is then connected to the host computer 15. Finally, the host computer 15 demodulates the measured parameters according to the pre-set algorithm and the relevant formula of the optical interference principle and combines multiple laser signals of different frequencies for display and recording.

[0030] In this embodiment, the MZ optical fiber sensor 3 adopts a single-multi-single structure optical fiber sensor with an "open cavity", such as Figure 2As shown, it is composed of an input single-mode optical fiber 8 and a first multi-core optical fiber 9 as the input end of the MZ optical fiber sensor 3, and an output single-mode optical fiber 11 as the output end, which are aligned and fused in sequence by a fusion splicer, and a cavity 10 is set on the first multi-core optical fiber 9 using femtosecond etching technology, that is, the cavity 10 is used to contact the external environment medium of the parameter to be measured, so that when the laser signal output by the laser 1 is transmitted through the first single-mode optical fiber 2 to the side where the input single-mode optical fiber 8 and the first multi-core optical fiber 9 are fused, the laser signal is divided into two parts, one part is transmitted in the cladding 12 of the MZ optical fiber sensor 3, and the other part is propagated in the cavity 10. When it reaches the connection between the first multi-core optical fiber 9 and the output single-mode optical fiber 11, the two parts of the laser signal are coupled here and return to the core of the output single-mode optical fiber 11. Since the two parts of the laser signal have experienced different optical paths, the two parts of the laser signal will interfere when coupled to the core of the output single-mode optical fiber 11, generating interference light;

[0031] When the external environment medium that the cavity 10 contacts changes, its refractive index for the laser signal will also change, causing the waveform data of the interference light output by the output single-mode optical fiber 11 to change, making it convenient for the spectrometer 7 to detect and record these waveform data in real time, and demodulate the changes in the parameters to be measured in the external environment through the host computer 15.

[0032] In addition, as a preferred technical solution, the cavity 10 is a rectangular cavity with a length of 500-2000 μm and a depth not greater than the radius of the first multi-core optical fiber 9, so as to facilitate effective contact with the external environment medium to be measured;

[0033] Furthermore, the cavity 10 may be provided with a metal film or covered with other sensitizing materials, so as to enhance the sensitivity of the MZ optical fiber sensor 3 to changes in different external environmental parameters.

[0034] In this embodiment, the space division multiplexer 5 serves as a center for concentrating and distributing multi-path interference light, and can utilize space division multiplexing technology to integrate and dispatch the multi-path interference light signals output by multiple MZ fiber sensors 3, thereby realizing multi-parameter measurement of the entire device and improving the integration of the device.

[0035] Specifically, the fiber core at the input end of the space division multiplexer 5 is composed of a plurality of second single-mode optical fibers 13, the number of which is the same as that of the MZ optical fiber sensors 3. Figure 3Taking the four-core case shown as an example, the geometric arrangement of the multiple second single-mode optical fibers 13 is the same as the core arrangement of the second multi-core optical fiber 6. The manufacturing method is as follows: the multiple second single-mode optical fibers 13 and the glass sleeve 14 are filled with adhesive and heated and cured at 100°C-120°C for 20-30 minutes to ensure the structural strength. The middle and rear portions of the glass sleeve 14 are formed by micro-tapering using an oxyhydrogen flame to form the output end of the space division multiplexer 5. After the glass sleeve 14 is tapered and thinned, each second single-mode optical fiber 13 inside becomes the core of the output end of the space division multiplexer 5, and the glass sleeve 14 becomes the new cladding.

[0036] Furthermore, the plurality of second single-mode optical fibers 13 are preferably arranged centrally and symmetrically to ensure the stability and uniformity of the interference optical signal during the multiplexing process and to reduce the loss and distortion of the interference optical signal;

[0037] When the fiber core at the output end of the space division multiplexer 5 is fused with the second multi-core optical fiber 6, the output end of the space division multiplexer 5 needs to be tapered, that is, to ensure that the fiber core at its output end is smaller than the core diameter of the second multi-core optical fiber 6 by 1-2 μm. In this way, when the space division multiplexer 5 is fused with the second multi-core optical fiber 6, the tolerance for fusion errors can be greatly improved and the fusion loss can be reduced.

[0038] The material of the protective shell of the space division multiplexer 5 is preferably polytetrafluoroethylene (PTFE). Polytetrafluoroethylene, a polymer material, can effectively prevent the external environment, such as soil, from corroding the structure of the space division multiplexer 5. The specific measurement steps of the utility model are:

[0039] First, introduce the liquid or gas to be measured into the cavity 10 of the MZ fiber optic sensor 3. Microfluidics or other suitable injection methods can be used to ensure that the substance to be measured is evenly and stably distributed within the cavity 10 and fully contacts the cavity structure. During the injection process, care should be taken to avoid the generation of bubbles, which can affect the propagation of the optical signal and the measurement results.

[0040] Laser 1 is turned on, and the laser signal propagates along a predetermined path. At the connection point of the MZ fiber sensor 3, a splitting phenomenon occurs, with some light propagating through the fiber's cladding 12 and the rest through cavity 10. Because the physical and chemical properties of the substance being measured affect the optical signal, a path length difference occurs between the light propagating through cavity 10 and the light propagating through cladding 12.

[0041] When the optical signal reaches the other connection, the two parts of light interfere due to the optical path difference. MZ fiber sensor 3 is connected to a second multi-core fiber 6 via a space-division multiplexer 5. This second multi-core fiber 6 is connected to a spectrometer 7 via a fiber jumper. This interference phenomenon produces different waveforms in different wavelength bands of spectrometer 7, which detects and records these waveform data in real time.

[0042] Spectrometer 7 transmits the detected optical signal to host computer 15, which demodulates the spectral data based on pre-set algorithms and formulas based on the principle of optical interference. First, the data is pre-processed to remove noise and interference signals. Then, through calculation and analysis, the various parameters of the measured quantity, such as the concentration, temperature, and pressure of the substance being measured, are demodulated. Finally, the demodulated parameters are displayed and recorded in the form of charts or data for user analysis and research.

[0043] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope defined by the claims of the present invention.

Claims

1. A multi-parameter measurement optical fiber sensing device based on space division multiplexing technology, comprising: Multiple lasers of different frequencies (1); A plurality of MZ fiber sensors (3) connected to the plurality of lasers (1) respectively via a plurality of first single-mode optical fibers (2); a space division multiplexer (5) connected to the plurality of MZ fiber sensors (3) via an optical fiber connector (4); an output end of the space division multiplexer (5) connected to a spectrometer (7) via a fusion spliced second multi-core optical fiber (6); and the spectrometer (7) connected to a host computer (15); The number of fiber cores of the space division multiplexer (5) is the same as the number of fiber cores of the second multi-core optical fiber (6), the number of MZ optical fiber sensors (3), and the number of lasers (1); The invention is characterized in that the MZ optical fiber sensor (3) is composed of an input single-mode optical fiber (8), a first multi-core optical fiber (9) and an output single-mode optical fiber (11), which are aligned and fused in sequence by a fusion splicer, and a cavity (10) is provided on the first multi-core optical fiber (9).

2. The multi-parameter measurement optical fiber sensing device based on space division multiplexing technology according to claim 1, characterized in that: The cavity (10) is a rectangular cavity with a length of 500-2000 μm and a depth no greater than the radius of the first multi-core optical fiber (9).

3. The multi-parameter measurement optical fiber sensing device based on space division multiplexing technology according to claim 2, characterized in that: Sensitization material is provided in the cavity (10).

4. The multi-parameter measurement optical fiber sensing device based on space division multiplexing technology according to claim 1, characterized in that: The fiber core of the space division multiplexer (5) is composed of a plurality of second single-mode optical fibers (13), and the geometric arrangement thereof is the same as the fiber core arrangement of the second multi-core optical fiber (6).

5. The multi-parameter measurement optical fiber sensing device based on space division multiplexing technology according to claim 4, characterized in that: The plurality of second single-mode optical fibers (13) are centrally symmetrically arranged.

6. The multi-parameter measurement optical fiber sensing device based on space division multiplexing technology according to claim 5, characterized in that: The protective shell material of the space division multiplexer (5) is polytetrafluoroethylene.

7. The multi-parameter measurement optical fiber sensing device based on space division multiplexing technology according to claim 1, characterized in that: When the output end of the space division multiplexer (5) is fused with the second multi-core optical fiber (6), the output end of the space division multiplexer (5) needs to be tapered so that the core of the output end is smaller than the core diameter of the second multi-core optical fiber (6) by 1-2 μm.

Images