Distributed optical fiber sensor and optical fiber sensing integrated system
By introducing point sensors, drive circuits and mechanical oscillators into distributed fiber sensors, combined with distributed fiber vibration sensing technology, flexible monitoring of various environmental physical quantities is achieved, solving the problems of system complexity and cost increase.
Patent Information
- Application Number
- CN202422403606.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-30
- Publication Date
- 2025-07-11
- Estimated Expiration
- 2034-09-30
AI Technical Summary
Existing distributed fiber optic sensors have increased system complexity and cost problems when monitoring multiple environmental physical quantities simultaneously.
Point sensors, driving circuits and mechanical oscillators are used to convert the environmental physical quantity into electrical signals and vibration signals to apply it to the optical fiber, and combined with distributed optical fiber vibration sensing technology for monitoring, it realizes seamless switching of various environmental physical quantity.
A flexible and universal monitoring of a variety of environmental physical quantities is achieved, simplifying system complexity and reducing costs.
Smart Images
Figure CN223091304U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of fiber optic sensing technology, and in particular, to a distributed fiber optic sensor and an integrated fiber optic communication and sensing system. Background Art
[0002] Distributed fiber optic sensing technology is a distributed technology that uses an optical fiber as a sensing element and detects environmental physical quantities (such as stress, temperature, vibration, etc.) along the optical fiber by measuring changes in optical signals (such as optical intensity, phase, frequency, etc.) in the optical fiber.
[0003] Since the sensitive parameters of the optical fiber to different environmental physical quantities are different, in the prior art, when constructing a distributed fiber optic sensor, a corresponding sensing mechanism is designed and adopted according to the specific type of the environmental physical quantity to be monitored. Although this specific design ensures high precision and high reliability in the measurement of environmental physical quantities by the distributed fiber optic sensor, when it is necessary to simultaneously monitor multiple different types of environmental physical quantities, it is necessary to deploy multiple different types of distributed fiber optic sensors accordingly, which undoubtedly increases the complexity and cost of the system. Summary of the Utility Model
[0004] In view of the above problems, this application provides a distributed fiber optic sensor and an integrated fiber optic communication and sensing system to solve the problems of system complexity and increased cost faced when simultaneously monitoring multiple environmental physical quantities. The specific solutions are as follows:
[0005] In a first aspect of this application, a distributed fiber optic sensor is provided, including: an optical fiber, a signal transmitting and processing device, n point sensors, n drive circuits, and n mechanical oscillators fixed on the optical fiber, where n≥1;
[0006] The i-th point sensor is used to convert the monitored environmental physical quantity into an electrical signal, and the magnitude of the electrical signal has a unique correspondence with the environmental physical quantity; i = 1, 2, 3, ……, n;
[0007] The output end of the i-th point sensor is connected to the input end of the i-th drive circuit, and the output end of the i-th drive circuit is connected to the input end of the i-th mechanical oscillator; the drive circuit is used to convert the electrical signal converted by the point sensor into a drive signal capable of driving the mechanical oscillator to generate mechanical vibration, and the frequency or amplitude of the mechanical vibration has a unique correspondence with the magnitude of the electrical signal converted by the point sensor;
[0008] The signal transmitting and processing device includes a signal transmitting and collecting device and a signal analyzing device; the signal transmitting and collecting device is connected between one end of the optical fiber and the input end of the signal analyzing device, and is used to transmit an optical signal to the optical fiber, collect the change in the optical signal caused by external vibration in the optical fiber, and output it to the signal analyzing device.
[0009] In a possible implementation, the signal transmitting and collecting device includes: a pulsed light source, an optical circulator, and a photodetector;
[0010] The line width of the optical signal emitted by the pulsed light source is lower than a preset value;
[0011] The optical circulator has ports 1, 2, and 3, where: the optical signal input from port 1 is output from port 2, and the optical signal input from port 2 is output from port 3;
[0012] The output end of the pulsed light source is connected to port 1 of the optical circulator;
[0013] Port 2 of the optical circulator is connected to one end of the optical fiber;
[0014] Port 3 of the optical circulator is connected to the input end of the photodetector;
[0015] The output end of the photodetector is connected to the input end of the signal analysis device.
[0016] In a possible implementation, the signal transmitting and collecting device further includes: a splitter;
[0017] The photodetector is replaced with a balanced photodetector; the output end of the pulsed light source is connected to the input end of the splitter; the first output end of the splitter is connected to port 1 of the optical circulator, and the second output end of the splitter is connected to another input end of the balanced photodetector.
[0018] In a possible implementation, the electrical signal converted by the point sensor is current or voltage.
[0019] In a possible implementation, the environmental physical quantity is the magnitude of stress, the magnitude of pressure, the magnitude of displacement, the temperature value, the hydrogen concentration, the gas concentration, the oxygen concentration, the methane concentration, or the carbon dioxide concentration.
[0020] In a possible implementation, the mechanical oscillator is fixed to the optical fiber through a fixture.
[0021] In a possible implementation, each mechanical oscillator is independently powered.
[0022] The second aspect of the present application provides another distributed optical fiber sensor, including: an optical switch, a signal transmitting and processing device, m optical fibers, at least one mechanical oscillator fixed to the j-th optical fiber, a driving circuit provided one-to-one with each mechanical oscillator, and a point sensor provided one-to-one with each driving circuit; j = 1, 2, 3, ……, m; m ≥ 2;
[0023] The point sensor is used to convert the monitored environmental physical quantity into an electrical signal, and there is a unique corresponding relationship between the magnitude of the electrical signal and the environmental physical quantity;
[0024] The output end of each point sensor is connected to the input end of its corresponding drive circuit, and the output end of each drive circuit is connected to the input end of its corresponding mechanical oscillator; the drive circuit is used to convert the electrical signal converted by the point sensor into a drive signal capable of driving the mechanical oscillator to generate mechanical vibration, and there is a unique corresponding relationship between the frequency or amplitude of the mechanical vibration and the magnitude of the electrical signal converted by the point sensor;
[0025] The signal transmitting and processing device includes a signal transmitting and collecting device and a signal analyzing device; the signal transmitting and collecting device is accessibly connected to different optical fibers through the optical switch by time-division multiplexing; the signal transmitting and collecting device is also connected to the signal analyzing device; the signal transmitting and collecting device is used to transmit an optical signal to the optical fiber, collect the change of the optical signal caused by external vibration in the optical fiber, and output it to the signal analyzing device.
[0026] A third aspect of the present application provides an optical fiber communication and sensing integrated system, including: a first optical multiplexer / demultiplexer, a second optical multiplexer / demultiplexer, a first optical communication device, a second optical communication device, and the distributed optical fiber sensor according to any implementation manner of the first aspect, the second aspect, the first aspect or the second aspect;
[0027] The first optical multiplexer / demultiplexer is connected to the first optical communication device, one end of the optical fiber in the distributed optical fiber sensor, and the signal transmitting and processing device in the distributed optical fiber sensor;
[0028] The second optical multiplexer / demultiplexer is connected to the second optical multiplexer / demultiplexer and the other end of the optical fiber.
[0029] By means of the above technical solution, the distributed optical fiber sensor provided by the present application first converts the monitored environmental physical quantity into an electrical signal through a point sensor, then converts the electrical signal into a vibration signal through a drive circuit and a mechanical oscillator and applies it to the optical fiber, and finally uses the distributed optical fiber vibration sensing technology to capture and analyze the vibration signal to identify the monitored environmental physical quantity. By arranging multiple point sensors of the same type at different positions along the optical fiber, multi-point monitoring of the same environmental physical quantity at different position points can be realized; by replacing the type of the point sensor, seamless switching to the monitoring of another type of environmental physical quantity can be achieved, which demonstrates the extremely high versatility and flexibility of the distributed optical fiber sensor and solves the problems of system complexity and cost increase faced when monitoring multiple environmental physical quantities simultaneously. Description of the Drawings
[0030] In conjunction with the accompanying drawings and with reference to the following specific embodiments, the above and other features, advantages and aspects of the various embodiments of the present disclosure will become more apparent. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic and that the original and elements are not necessarily drawn to scale.
[0031] Figure 1 Schematic diagram of the structure of a distributed optical fiber sensor provided by this application;
[0032] Figure 2 Vibration amplitude time-space waterfall diagram provided by this application;
[0033] Figure 3 Schematic diagram of the structure of another distributed optical fiber sensor provided by this application;
[0034] Figure 4 Schematic diagram of the structure of another distributed optical fiber sensor provided by this application;
[0035] Figure 5 Schematic diagram of the structure of another distributed optical fiber sensor provided by this application;
[0036] Figure 6 Schematic diagram of the structure of an optical fiber communication and sensing integrated system provided by this application. Specific embodiments
[0037] Distributed optical fiber sensing technology is a distributed technology that uses optical fiber as a sensing element and detects environmental physical quantities (such as stress, temperature, vibration, etc.) along the optical fiber by measuring changes in optical signals (such as light intensity, phase, frequency, etc.) in the optical fiber. The reason why optical fiber has become an ideal choice for long-distance sensing of various environmental physical quantities is mainly due to its unique physical properties: 1) small size and easy to deploy; 2) long-distance transmission ability and wide coverage; 3) high immunity to electromagnetic interference, ensuring the stability and reliability of data transmission.
[0038] Since optical fibers are sensitive to different environmental physical quantities with different parameters, in the prior art, when constructing a distributed optical fiber sensor, the corresponding sensing mechanism will be designed and adopted according to the specific type of the environmental physical quantity to be monitored. For example, the sensitive parameters of optical fibers to temperature and stress are different. For optical fiber temperature sensing, an optical fiber Raman time domain reflectometer is usually used as a distributed optical fiber temperature sensor. This instrument utilizes the characteristic that the intensity of anti-Stokes light generated in the Raman scattering process in the optical fiber is sensitive to temperature, and evaluates the temperature distribution along the optical fiber by monitoring the change in the power of the anti-Stokes light. In terms of optical fiber stress sensing, an optical fiber Brillouin time domain reflectometer or an optical fiber Brillouin time domain analyzer is mostly selected as a distributed optical fiber stress sensor. Both of these two instruments are based on the principle that when the optical fiber is subjected to external stress, the frequency of the Brillouin scattered light in the optical fiber will change (i.e., Brillouin frequency shift), and the stress distribution along the optical fiber is evaluated by measuring the change in the Brillouin frequency shift.
[0039] Since the existing distributed optical fiber sensors are often specific in design and application, that is, each type of distributed optical fiber sensor can generally only be used to detect a certain specific type of environmental physical quantity, such as temperature, stress, vibration, etc. Although this specific design ensures the high precision and high reliability of the distributed optical fiber sensor in measuring environmental physical quantities, when it is necessary to simultaneously monitor multiple different types of environmental physical quantities, it is necessary to deploy multiple different types of distributed optical fiber sensors accordingly, which not only increases the complexity of the system but also significantly increases the cost.
[0040] To solve the problems of system complexity and increased cost faced when simultaneously monitoring multiple environmental physical quantities, the embodiments of the present application provide a distributed optical fiber sensor, which integrates a point sensor, a drive circuit, a mechanical oscillator, and distributed optical fiber vibration sensing technology: first, the environmental physical quantity to be monitored is converted into an electrical signal by the point sensor, then the electrical signal is converted into a vibration signal by the drive circuit and the mechanical oscillator and applied to the optical fiber, and finally the distributed optical fiber vibration sensing technology is used to capture and analyze the vibration signal to identify the environmental physical quantity to be monitored. By setting multiple point sensors of the same type at different positions along the optical fiber, multi-point monitoring of the same environmental physical quantity at different positions can be realized; by replacing the type of the point sensor, seamless switching to the monitoring of another type of environmental physical quantity can be achieved. It can be seen that this distributed optical fiber sensor exhibits extremely high versatility and flexibility, thus solving the problems of system complexity and increased cost faced when simultaneously monitoring multiple environmental physical quantities.
[0041] The following will detail a distributed optical fiber sensor provided by an embodiment of the present application in conjunction with the accompanying drawings. As can be known to those of ordinary skill in the art, with the development of technology and the emergence of new scenarios, the technical solutions provided by the embodiments of the present application are equally applicable to similar technical problems.
[0042] Terms such as "first" and "second" in the specification, claims, and the above-mentioned accompanying drawings of the present application are used to distinguish similar objects and do not necessarily describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances, which is only a way of distinguishing objects with the same attributes when describing the embodiments of the present application. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion, so that a process, method, system, product, or device including a series of units does not have to be limited to those units, but may include other units not clearly listed or inherent to these processes, methods, products, or devices.
[0043] See Figure 1 , a distributed optical fiber sensor provided by an embodiment of the present application includes: an optical fiber L1, a signal transmitting and processing device, n point sensors, n driving circuits, and n mechanical oscillators fixed on the optical fiber, where n≥1;
[0044] The output end of the i-th point sensor is connected to the input end of the i-th driving circuit, and the output end of the i-th driving circuit is connected to the input end of the i-th mechanical oscillator, where i = 1, 2, 3,..., n;
[0045] The signal transmitting and processing device includes a signal transmitting and collecting device and a signal analyzing device; the signal transmitting and collecting device is connected between one end of the optical fiber L1 and the input end of the signal analyzing device.
[0046] The following will detail the characteristics of each component:
[0047] I. Point sensor
[0048] A point sensor can only measure a certain environmental physical quantity within a very small range around it, and its physical size is generally small. Specifically, after the point sensor is placed at the measurement point, the point sensor is responsible for sensing the environmental physical quantity at the measurement point and converting the environmental physical quantity into an electrical signal through an internal conversion mechanism. The magnitude of the electrical signal has a unique correspondence with the environmental physical quantity (that is, each specific environmental physical quantity corresponds to a specific electrical signal magnitude, and this correspondence is determined and unambiguous).
[0049] The electrical signal is usually current or voltage. The environmental physical quantity can be the magnitude of stress, the magnitude of pressure, the magnitude of displacement, temperature value, hydrogen concentration, gas concentration, oxygen concentration, methane concentration, carbon dioxide concentration, etc., without limitation.
[0050] Wherein, when the environmental physical quantity is the magnitude of stress, the point sensor is a stress point sensor, and the distributed fiber optic sensor is a distributed fiber optic stress sensor.
[0051] When the environmental physical quantity is the magnitude of pressure, the point sensor is a pressure point sensor, and the distributed fiber optic sensor is a distributed fiber optic pressure sensor.
[0052] When the environmental physical quantity is the magnitude of displacement, the point sensor is a displacement point sensor, and the distributed fiber optic sensor is a distributed fiber optic displacement sensor.
[0053] When the environmental physical quantity is temperature value, the point sensor is a temperature point sensor, and the distributed fiber optic sensor is a distributed fiber optic temperature sensor.
[0054] When the environmental physical quantity is hydrogen concentration, the point sensor is a hydrogen point sensor, and the distributed fiber optic sensor is a distributed fiber optic hydrogen sensor.
[0055] When the environmental physical quantity is gas concentration, the point sensor is a gas point sensor, and the distributed fiber optic sensor is a distributed fiber optic gas sensor.
[0056] When the environmental physical quantity is oxygen concentration, the point sensor is an oxygen point sensor, and the distributed fiber optic sensor is a distributed fiber optic oxygen sensor.
[0057] When the environmental physical quantity is methane concentration, the point sensor is a methane point sensor, and the distributed fiber optic sensor is a distributed fiber optic methane sensor.
[0058] When the environmental physical quantity is carbon dioxide concentration, the point sensor is a carbon dioxide point sensor, and the distributed fiber optic sensor is a distributed fiber optic carbon dioxide sensor.
[0059] II. Driving Circuit and Mechanical Oscillator
[0060] A mechanical oscillator refers to an object or system that can perform reciprocating motion near an equilibrium position. This form of motion usually follows the law of simple harmonic vibration, that is, the magnitude of the force on the object is proportional to the distance from its equilibrium position, and the direction of the force is always towards the equilibrium position. Parameters such as the vibration frequency and amplitude of the mechanical oscillator can be precisely controlled, which makes it an important tool for studying vibration phenomena, signal processing, measurement and other applications.
[0061] A driving circuit is configured to convert the electrical signal converted by the point sensor into a driving signal capable of driving a mechanical oscillator to generate mechanical vibrations, and there is a unique correspondence between the vibration frequency or vibration amplitude of the mechanical vibrations and the magnitude of the electrical signal converted by the point sensor. This is equivalent to the driving circuit and the mechanical oscillator jointly performing vibration encoding on the electrical signal converted by the point sensor. Through vibration encoding, the environmental physical quantity monitored by the point sensor is represented by a specific vibration characteristic (such as a specific vibration amplitude or a specific vibration frequency, etc.), so as to be identified and decoded by the distributed optical fiber vibration sensing technology subsequently, thereby realizing the monitoring of the environmental physical quantity.
[0062] For example, taking the case where the environmental physical quantity monitored by the point sensor is represented by a specific vibration amplitude through vibration encoding, and using encoding 1 to represent strong vibration and encoding 0 to represent weak vibration as an example, refer to Figure 2 the shown vibration amplitude time - space waterfall diagram. The horizontal axis of this waterfall diagram is the optical fiber length position, and the vertical axis is time. At a certain optical fiber length position point Lx, the driving circuit and the mechanical oscillator jointly perform vibration encoding on the electrical signal converted by the point sensor, obtaining a vibration signal whose vibration amplitude changes with time as 0110011101. Then this string of vibration signals corresponds to a unique magnitude of the environmental physical quantity.
[0063] III. Optical fiber L1 and signal transmitting and processing device
[0064] The optical fiber L1 is laid in the area to be measured. n mechanical oscillators are arranged and fixed on this optical fiber L1 by means of fixtures or other methods.
[0065] The signal transmitting and processing device includes a signal transmitting and collecting device and a signal analyzing device. The signal transmitting and collecting device is connected between one end of the optical fiber L1 and the input end of the signal analyzing device, and is used to transmit an optical signal to the optical fiber L1, collect the change in the optical signal in the optical fiber L1 caused by external vibrations, and output it to the ADC (Analog to Digital Converter) port of the signal analyzing device. The signal analyzing device utilizes the distributed optical fiber vibration sensing principle (that is, by monitoring the change in the optical signal in the optical fiber caused by external vibrations) to realize the real - time acquisition and positioning analysis of the vibration information along the optical fiber, and through the identification and decoding processing of these vibration information, obtain the environmental physical quantity monitored by the point sensor.
[0066] In summary, the distributed optical fiber sensor provided by the present application integrates a point sensor, a drive circuit, a mechanical oscillator, and a distributed optical fiber vibration sensing technology. By arranging multiple point sensors of the same type at different positions along the optical fiber, multi-point monitoring of the same environmental physical quantity at different positions can be achieved. Moreover, by replacing one type of point sensor with another type of point sensor, seamless switching to the monitoring of another type of environmental physical quantity can be achieved. It can be seen that the distributed optical fiber sensor provided by the embodiments of the present application exhibits extremely high versatility and flexibility, thus greatly simplifying the complexity of the system and saving costs in application scenarios where multiple environmental physical quantities are monitored simultaneously.
[0067] In a possible implementation, referring to Figure 3 , the signal transmitting and collecting device in any of the above-mentioned distributed optical fiber sensors specifically includes: a pulsed light source, an optical circulator, and a photodetector;
[0068] The line width of the optical signal emitted by the pulsed light source is lower than a preset value, and this pulsed light source is generally called a narrow line width pulsed light source;
[0069] The optical circulator has ports 1, 2, and 3, where: the optical signal input from port 1 is output from port 2, and the optical signal input from port 2 is output from port 3;
[0070] The output end of the pulsed light source is connected to port 1 of the optical circulator;
[0071] Port 2 of the optical circulator is connected to one end of the optical fiber L1;
[0072] Port 3 of the optical circulator is connected to the input end of the photodetector;
[0073] The output end of the photodetector is connected to the input end of the signal analysis device.
[0074] Next, the working principle of the Figure 3 shown embodiment will be described in detail:
[0075] The pulsed light source is used to emit an excitation pulsed light (i.e., an optical signal), which has a definite start time and end time, and specific spectral components. This excitation pulsed light enters port 1 of the optical circulator.
[0076] An optical circulator is a multi-port optical device with non-reciprocal characteristics. The non-reciprocal characteristics mean that it allows optical signals to be transmitted from one port to the next in a specific order while blocking the reverse transmission of optical signals. The optical circulator has N (N≥3) ports, which are sequentially defined as port 1, port 2, port 3, ……, port N according to the transmission direction of the optical signal. These N ports form a continuous channel. Specifically, when light is input from port 1, the light is output from port 2 with almost no loss, and there is almost no light output at other ports; when light is input from port 2, the light is output from port 3 with almost no loss, and there is almost no light output at other ports, and so on. The non-reciprocity of the optical circulator makes it an important device in two-way communication, and it can complete the task of separating forward and backward transmitted light.
[0077] The pulsed pump light entering port 1 of the optical circulator is output from port 2 of the optical circulator and then enters optical fiber L1 and is transmitted in optical fiber L1. The pulsed pump light transmitted in optical fiber L1 continuously generates backward Rayleigh scattered light propagating in the opposite direction to the pulsed pump light due to the Rayleigh scattering effect. The so-called Rayleigh scattering effect mainly describes a scattering phenomenon that occurs when light propagates in a medium and encounters tiny particles or inhomogeneities inside the medium (such as material defects, refractive index changes, etc.). A part of the scattered light will propagate backward along optical fiber L1, which is called backward Rayleigh scattered light.
[0078] The line width of a pulsed light source is a parameter that describes the spectral width of the pulsed pump light emitted by the pulsed light source. Specifically, it refers to the width between two frequencies corresponding to half the peak height (sometimes also taking the 1 / e height) in the spectrum. The wider this width is, the wider its spectral width is, and the more dispersed the emitted light is in terms of frequency. While a narrow line width means that the light wave emitted by the pulsed light source is very concentrated in terms of frequency, that is, the spectral line is very narrow.
[0079] This characteristic of a narrow line width makes the light wave emitted by the pulsed light source have extremely strong coherence. Coherence refers to the ability of two or more light waves to interfere with each other significantly when they meet in space. When optical fiber L1 is subjected to external vibration, the local refractive index or length of optical fiber L1 will change, which will affect the phase of light when it propagates in optical fiber L1. Due to the phase change caused by the vibration of optical fiber L1, when light propagates in optical fiber L1 and undergoes backward Rayleigh scattering, there will be a phase difference between these backward Rayleigh scattered lights. Due to the high coherence of the narrow line width pulsed light source, when these backward Rayleigh scattered lights propagate and return in optical fiber L1, they will undergo self-coherence effects due to the phase difference caused by the vibration of optical fiber L1.
[0080] After the optical signal with the optical power or phase change caused by the self-coherence effect is transmitted back to port 2 of the circulator, it is output from port 3 of the circulator and detected by the optical detector. The optical detector converts the detected optical signal into an electrical signal and outputs it to the signal analysis device. The change of the optical signal detected by the optical detector can sensitively and real-time reflect the characteristics such as the position, frequency and intensity of the external vibration of the optical fiber L1. These characteristics have a unique corresponding relationship with the environmental physical quantities monitored by the point sensors located at the corresponding position points, thus realizing the monitoring of the environmental physical quantities along the optical fiber. In particular, the phase of the strongly coherent backscattered Rayleigh light shows extremely high sensitivity to the external vibration of the optical fiber L1. This means that even a tiny vibration can leave an obvious trace in the optical signal through the self-coherence effect and thus be accurately captured by the optical detector.
[0081] In summary, due to its strong coherence, the narrow linewidth excitation pulse light generates strongly coherent Rayleigh scattered light opposite to the excitation pulse light through the Rayleigh scattering effect during propagation. When these strongly coherent backscattered Rayleigh lights propagate and return in the optical fiber L1, obvious phase differences will occur due to the vibration of the optical fiber L1, and then significant self-coherence effects will occur. The self-cohered signal can accurately reflect the characteristics such as the position, frequency and intensity of the vibration. These characteristics have a unique corresponding relationship with the environmental physical quantities monitored by the point sensors located at the corresponding position points, thus realizing the monitoring of the environmental physical quantities along the optical fiber.
[0082] Based on the previous embodiment, refer to Figure 4 , the signal transmitting and collecting device further includes: a splitter; the above optical detector is replaced by a balanced photodetector; the output end of the pulse light source is connected to the input end of the splitter; the first output end of the splitter is connected to port 1 of the optical circulator, and the second output end of the splitter is connected to another input end of the balanced photodetector.
[0083] Specifically, after the excitation pulse light emitted by the pulse light source enters the splitter, the splitter uses its internal physical mechanisms (such as grating diffraction, fiber melting and tapering, etc.) to divide the excitation pulse light into two paths. These two paths of excitation pulse light are the same in intensity, spectral composition and time, and maintain strict synchronization. The splitter outputs the two divided paths of excitation pulse light to port 1 of the optical circulator and the balanced photodetector respectively.
[0084] The signal sent by the optical splitter to the balanced photodetector is called the intrinsic light (intrinsic light refers to the radiation characteristics inherent in the light source itself and not affected by external factors. Intrinsic light can be understood as a part of the original excitation pulse light). The balanced photodetector is a special type of photodetector that adds a balanced circuit at the front end of the photoelectric converter. The balanced circuit processes the intrinsic light and the signal output from port 3 of the optical circulator and then sends it to the subsequent photoelectric converter, which can effectively cancel the stray light in the photosensitive element and the noise in the circuit, and greatly improve the signal-to-noise ratio and sensitivity of the photodetector.
[0085] In a possible implementation, each of the mechanical oscillators in any of the above embodiments is independently powered and can be configured individually according to the required quantity and type. This means that the system can be flexibly expanded or reduced according to actual needs to adapt to different detection tasks and environmental conditions. In addition, the mechanical oscillator does not need to be bound to a specific distributed optical fiber sensor, which increases the versatility and flexibility of the system.
[0086] In a possible implementation, refer to Figure 5 , any of the above embodiments can also achieve multi-channel expansion, that is, the embodiments of the present application provide another distributed optical fiber sensor, including: an optical switch, a signal transmitting and processing device, m optical fibers L1~Lm, at least one mechanical oscillator fixed on the j-th optical fiber ( Figure 5 only n mechanical oscillators are fixed on each optical fiber for illustration, n≥1), a drive circuit provided in one-to-one correspondence with each mechanical oscillator, and a point sensor provided in one-to-one correspondence with each drive circuit; j = 1, 2, 3,..., m; m≥2;
[0087] The point sensor is used to convert the monitored environmental physical quantity into an electrical signal, and the magnitude of the electrical signal has a unique correspondence with the environmental physical quantity;
[0088] The output end of each point sensor is connected to the input end of its corresponding drive circuit, and the output end of each drive circuit is connected to the input end of its corresponding mechanical oscillator; the drive circuit is used to convert the electrical signal converted by the point sensor into a drive signal capable of driving the mechanical oscillator to generate mechanical vibration, and the frequency or amplitude of the mechanical vibration has a unique correspondence with the magnitude of the electrical signal converted by the point sensor;
[0089] The signal transmitting and processing device includes a signal transmitting and collecting device and a signal analyzing device; the signal transmitting and collecting device accesses different optical fibers through time-division multiplexing by the optical switch; the signal transmitting and collecting device is also connected to the signal analyzing device; the signal transmitting and collecting device is used to emit an optical signal to the optical fiber and collect the change of the optical signal in the optical fiber caused by external vibration, and output it to the signal analyzing device.
[0090] Figure 5 The working principle of the illustrated embodiment is as follows: The optical switch can distribute optical signals to different optical fiber channels according to different time slices, thereby realizing the multiplexing and transmission of multiple optical signals. Compared with the foregoing embodiments, Figure 5 the illustrated embodiment increases the number and range of the mechanical oscillator distribution, forming a more three-dimensional sensing head lattice.
[0091] Optical fiber communication networks, with their large-capacity, long-distance, and highly reliable information transmission capabilities, have become an important infrastructure for communication networks and are widely used in multiple industries such as telecommunications, power, oil, and gas. With the continuous progress of technology, how to efficiently utilize the existing optical fiber communication network and achieve the effective integration of communication and sensing functions has become the focus of industry attention. The proposal of the integrated optical fiber communication and sensing (usually referred to as "communication-sensing integration") technology is precisely to address this challenge. The communication-sensing integration technology is based on the sharing of optical fiber cable resources. It can not only efficiently transmit communication data through optical fibers but also innovatively utilize the sensitive characteristics of optical fibers to the external environment to sense environmental changes in real time (i.e., realizing the functions of data transmission and environmental sensing on the same optical fiber), thereby innovating and expanding the functions of traditional optical fiber communication networks.
[0092] Based on this, the optical fibers used in any of the embodiments provided in this application can be multiplexed with the optical fibers used for communication to achieve communication-sensing integration. It only needs to combine the signals of the optical communication device and the output end of the distributed optical fiber sensor in the same optical fiber through an optical multiplexer / demultiplexer. Of course, the optical wavelengths used by the distributed optical fiber sensor need to be different from those used by the optical communication device. The specific technical solution is as Figure 6 shown. The embodiment of this application provides an optical fiber communication-sensing integration system, including: a first optical multiplexer / demultiplexer, a second optical multiplexer / demultiplexer, a first optical communication device, a second optical communication device, and a distributed optical fiber sensor provided in any of the foregoing embodiments;
[0093] The first optical multiplexer / demultiplexer is connected to one end of the optical fibers in the first optical communication device, the distributed optical fiber sensor, and the signal transmitting and processing device in the distributed optical fiber sensor;
[0094] The second optical multiplexer / demultiplexer is connected to the second optical multiplexer / demultiplexer and the other end of the optical fiber.
[0095] Figure 6 The working principle of the illustrated embodiment is as follows:
[0096] The optical multiplexer / demultiplexer integrates an optical multiplexer and an optical demultiplexer, which are passive optical devices used in transmission methods such as wavelength division multiplexing.
[0097] Among them, an optical multiplexer, whose function is to combine (or merge) optical signals output by multiple transmitters with different wavelengths together, and then input them into an optical fiber for transmission. In this way, multiple optical signals can be transmitted simultaneously in the same optical fiber, greatly improving the transmission efficiency of the optical fiber.
[0098] An optical demultiplexer, whose function is opposite to that of the optical multiplexer. It is responsible for separating multiple composite optical signals with different wavelengths transmitted from an optical fiber according to different optical wavelengths and distributing them to different receivers. In this way, each receiver can receive the optical signal with the wavelength it needs.
[0099] By utilizing the characteristics of the optical multiplexer and demultiplexer, the first optical communication device and the second optical communication device can communicate through an optical fiber. At the same time, the distributed optical fiber sensor can reuse the same optical fiber for optical fiber sensing, realizing the integration of optical fiber communication and sensing.
[0100] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the embodiments of the present application. Therefore, the embodiments of the present application will not be limited to these embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A distributed optical fiber sensor, characterized in that, Including: An optical fiber, a signal transmitting and processing device, n point sensors, n drive circuits, and n mechanical oscillators fixed on the optical fiber, where n≥1; The i-th point sensor is used to convert the monitored environmental physical quantity into an electrical signal, and the magnitude of the electrical signal has a unique correspondence with the environmental physical quantity; i = 1, 2, 3, ……, n; The output end of the i-th point sensor is connected to the input end of the i-th drive circuit, and the output end of the i-th drive circuit is connected to the input end of the i-th mechanical oscillator; The drive circuit is used to convert the electrical signal converted by the point sensor into a drive signal capable of driving the mechanical oscillator to generate mechanical vibration, and the frequency or amplitude of the mechanical vibration has a unique correspondence with the magnitude of the electrical signal converted by the point sensor; The signal transmitting and processing device includes a signal transmitting and collecting device and a signal analyzing device; the signal transmitting and collecting device is connected between one end of the optical fiber and the input end of the signal analyzing device, and is used to emit an optical signal to the optical fiber and collect the change of the optical signal in the optical fiber caused by external vibration, and output it to the signal analyzing device.
2. The distributed optical fiber sensor according to claim 1, characterized in that, The signal transmitting and collecting device includes: a pulsed light source, an optical circulator, and a photodetector; The line width of the optical signal emitted by the pulsed light source is lower than a preset value; The optical circulator has ports 1, 2, and 3, where: the optical signal input from port 1 is output from port 2, and the optical signal input from port 2 is output from port 3; The output end of the pulsed light source is connected to port 1 of the optical circulator; Port 2 of the optical circulator is connected to one end of the optical fiber; Port 3 of the optical circulator is connected to the input end of the photodetector; The output end of the photodetector is connected to the input end of the signal analyzing device.
3. The distributed optical fiber sensor according to claim 2, wherein The signal transmitting and collecting device further includes: an optical splitter; The photodetector is replaced by a balanced photodetector; the output end of the pulsed light source is connected to the input end of the optical splitter; the first output end of the optical splitter is connected to port 1 of the optical circulator, and the second output end of the optical splitter is connected to another input end of the balanced photodetector.
4. The distributed optical fiber sensor according to any one of claims 1 to 3, characterized in that, The electrical signal converted by the point sensor is current or voltage.
5. The distributed optical fiber sensor according to any one of claims 1 to 3, characterized in that The environmental physical quantity is stress magnitude, pressure magnitude, displacement magnitude, temperature value, hydrogen concentration, gas concentration, oxygen concentration, methane concentration, or carbon dioxide concentration.
6. The distributed optical fiber sensor according to any one of claims 1 to 3, characterized in that The mechanical oscillator is fixed on the optical fiber by a fixture.
7. The distributed optical fiber sensor according to any one of claims 1 to 3, characterized in that, Each mechanical oscillator is independently powered.
8. A distributed optical fiber sensor, characterized in that, Including: An optical switch, a signal transmitting and processing device, m optical fibers, at least one mechanical oscillator fixed on the j-th optical fiber, a drive circuit provided in one-to-one correspondence with each mechanical oscillator, and a point sensor provided in one-to-one correspondence with each drive circuit; j = 1, 2, 3, ……, m; m≥2; The point sensor is used to convert the monitored environmental physical quantity into an electrical signal, and the magnitude of the electrical signal has a unique correspondence with the environmental physical quantity; The output end of each point sensor is connected to the input end of its corresponding drive circuit, and the output end of each drive circuit is connected to the input end of its corresponding mechanical oscillator; the drive circuit is configured to convert the electrical signal converted by the point sensor into a drive signal capable of driving the mechanical oscillator to generate mechanical vibration, and the frequency or amplitude of the mechanical vibration has a unique corresponding relationship with the magnitude of the electrical signal converted by the point sensor; The signal transmitting and processing device includes a signal transmitting and collecting device and a signal analyzing device; the signal transmitting and collecting device is access different optical fibers through time-division multiplexing by the optical switch; the signal transmitting and collecting device is also connected to the signal analyzing device; the signal transmitting and collecting device is configured to transmit an optical signal to the optical fiber and collect the change of the optical signal caused by external vibration in the optical fiber, and output it to the signal analyzing device.
9. An integrated optical fiber communication and sensing system, characterized in that, Comprising: A first optical multiplexer / demultiplexer, a second optical multiplexer / demultiplexer, a first optical communication device, a second optical communication device, and the distributed optical fiber sensor according to any one of claims 1 to 8; The first optical multiplexer / demultiplexer is connected to the first optical communication device, one end of the optical fiber in the distributed optical fiber sensor, and the signal transmitting and processing device in the distributed optical fiber sensor; The second optical multiplexer / demultiplexer is connected to the second optical multiplexer / demultiplexer and the other end of the optical fiber.