阅读说明：本技术 一种光纤侧向散射信号的获取装置及探测方法 (Device for acquiring optical fiber side scattering signals and detection method ) 是由 李新碗 孙钊 肖芬 吕明星 于 2020-12-16 设计创作，主要内容包括：一种光纤侧向散射信号的获取装置及探测方法,装置包括：信号采集装置,用于采集光纤通信中的传输信号的散射光；环境光底噪隔绝装置,用于覆盖所述的信号采集装置,使信号采集装置处于一个隔光隔音的封闭环境中；数据处理平台,用于接收信号采集结构装置传输的模拟信号,处理后输出数字信号；信号恢复输出端,用于接收数据处理平台传输的数字信号,并输出整形的数字信号。本发明利用光传输介质的散射效应,通过散射空间内的高效率收集,探测通信光纤的侧向散射信号,提取信号波形,并根据传输光信号与散射信号的强度一致性,恢复光纤中的传输信息。可方便快捷地对光纤传输信号进行探测,为光纤安全性的建设和未来光通信的系统搭建多样性提供了可能。(An optical fiber side scattering signal acquisition device and a detection method are provided, the device comprises: the signal acquisition device is used for acquiring scattered light of transmission signals in optical fiber communication; the ambient light bottom noise isolation device is used for covering the signal acquisition device and enabling the signal acquisition device to be in a light-isolating and sound-insulating closed environment; the data processing platform is used for receiving the analog signals transmitted by the signal acquisition structure device and outputting digital signals after processing; and the signal recovery output end is used for receiving the digital signal transmitted by the data processing platform and outputting the shaped digital signal. The invention utilizes the scattering effect of the optical transmission medium, detects the side scattering signal of the communication optical fiber through high-efficiency collection in the scattering space, extracts the signal waveform, and recovers the transmission information in the optical fiber according to the intensity consistency of the transmission optical signal and the scattering signal. The optical fiber transmission signal can be conveniently and rapidly detected, and the possibility is provided for the construction of optical fiber safety and the diversity of system construction of future optical communication.)

1. An apparatus for acquiring a side scatter signal of an optical fiber, comprising:

the signal acquisition device (1) is used for acquiring scattered light of transmission signals in optical fiber communication;

the environment light bottom noise isolation device (2) is used for covering the signal acquisition device (1) and enabling the signal acquisition device (1) to be in a light-isolation and sound-isolation closed environment;

the data processing platform (3) is used for receiving the analog signals transmitted by the signal acquisition structure device (1) and outputting digital signals after processing;

and the signal recovery output end (4) is used for receiving the digital signal transmitted by the data processing platform (3) and outputting the shaped digital signal.

2. The device for acquiring the side scattering signal of the optical fiber according to claim 1, wherein the signal acquisition device (1) comprises a panel module (16), and a concave reflecting mirror (5), an optical fiber clamp (6) and a photomultiplier module (7) which are arranged on the panel module (16); the optical fiber clamp (6) is provided with a V-shaped groove for embedding the optical fiber (14) with the coating layer and the cladding removed; the optical fiber clamp (6) is arranged between the concave reflector (5) and the photomultiplier (7), the mirror surface of the concave reflector (5), the optical fiber (14) and the detection lens end surface of the photomultiplier (7) are parallel, and the focal length f of the concave reflector (5)₁Equal to the distance between the detection lens and the end face of the detection lens of the photomultiplier (7).

3. The device for acquiring the side scattering signal of the optical fiber according to claim 2, wherein the concave mirror (5) reflects and collects the scattered light (15) scattered in the opposite direction to the end of the photomultiplier (7) to the light signal receiving surface of the photomultiplier (7), and the photomultiplier (7) converts the collected light intensity time signal into an analog level signal (12) and inputs the analog level signal into the data processing platform (3).

4. The device for acquiring the side scattering signal of the optical fiber according to claim 1 or 2, wherein the ambient light noise floor isolating device (2) is composed of a five-surface closed-connected shell, the bottom of the shell can be covered and buckled on the panel module (16), the shell is provided with a mounting hole for the optical fiber (14) and the detection lens of the photomultiplier module (7) to pass through, and the periphery of the mounting hole is provided with a hinge (8), a hinge (9) and a magnetic strip (10).

5. The device for acquiring fiber-optic side scatter signals according to claim 4, wherein a snap (11) is provided at the bottom periphery of the housing for mounting and dismounting with the panel module (16).

6. The apparatus for acquiring fiber-optic side scatter signals according to claim 1, wherein said data processing platform (3) intelligently calculates 0/1 signal decision threshold for the detected analog signals (12), and said signal recovery output terminal (4) outputs the shaped digital signals after calculating the above information.

7. Method for signal detection using an apparatus for acquiring side-scattered signals from an optical fiber according to any of claims 1 to 6, characterized in that it comprises the following steps:

step 1) initialization installation: selecting a detection point of the optical fiber (14), removing a coating layer and a cladding of the optical fiber (14) by using a chemical or physical method, fixing the coating layer and the cladding in a V-shaped groove of an optical fiber clamp (6), keeping the optical fiber (14) and the end face of a detection lens of a photomultiplier module (7) in parallel, and isolating the detection point by an ambient light background noise isolation device (2).

Step 2) collecting optical fiber scattering signals: in the process of optical fiber communication, a scattered light signal (15) escapes from a detection point, and the scattered light signal (15) opposite to the direction of the photomultiplier module (7) is reflected by the concave reflecting mirror (5) and converged on a light signal receiving surface of the photomultiplier module (7);

the diameter of the end face of a detection lens of the photomultiplier module (7) is l₀The core diameter of the optical fiber (14) is d₀When the distance between the photomultiplier (7) and the fiber core of the optical fiber (14) is d, the collection efficiency e1 of the scattered light is as follows:

after the signals of the different-end scattered light (15) are reflected and converged by using the concave reflector (5), the detection efficiency e2 is as follows:

l₁is the diameter of the concave reflector (5), f is a concave surfaceThe focal length of the reflector (5);

step 3), shaping and outputting of signals: the photomultiplier module (7) converts the collected light intensity signal into a level signal W to form an analog waveform related to the light intensity, and the data processing platform (3) calculates the analog waveform to obtain a high level threshold value V_HAnd a low level threshold value V_LThe analog level outputs a shaped digital signal D after being shaped by two thresholds, and the formula is as follows:

in the formula, V₁Is the highest level value of the level signal W, V₂Is the lowest level value;

if W≥V_H，D＝1

if W≤V_L，D＝0 。

Technical Field

The invention relates to a signal detection and recovery technology of an optical fiber, in particular to an acquisition device and a detection method of an optical fiber side scattering signal.

Background

By virtue of the advantages of wide bandwidth, large capacity, high speed and the like, optical fiber communication has become an important support of modern communication networks. Especially after an All Optical Network (AON) and an Automatic Switching Optical Network (ASON) appear, the optical network integrates more advantages of transparency, intellectualization, rasterization and the like, and the application prospect is wider and longer. Currently, over 90% of the information worldwide is carried by optical networks. With the increasing dependence of modern society on optical fiber network communication, the information security of optical fiber communication becomes the key point of communication service attention in many fields, and the "natural" security of optical fiber communication cannot be guaranteed 100%.

Currently, there are several methods for detecting optical fiber information: the optical fiber bending method is a representative method, the optical fiber information is obtained by controlling the bending radius of the optical fiber to obtain the optical power, when the optical fiber is bent greatly, the bending radius is comparable to the diameter of a fiber core of the optical fiber, the transmission characteristic is changed, a large number of conduction modes are converted into radiation modes, the radiation modes are not transmitted continuously, but enter a cladding and are absorbed by the cladding or a coating layer, but the bending process tends to cause the change of mechanical characteristics; the V-shaped groove notching method is a method for tapping an optical fiber signal by leading out a V-shaped groove close to a fiber core. It requires the included angle between the tangent plane of the V-shaped groove and the transmission direction of the optical fiber signal to be larger than the critical angle of complete reflection. When this condition is reached, complete reflection occurs of a portion of the signal propagating in the protective layer and a signal having a superposition effect at the V-groove cut surface, resulting in signal leakage through the fiber boundary. This method requires precise cutting into the fiber and polishing, and requires a long time for installation; the grating method utilizes an ultraviolet laser to generate ultraviolet light for coherent superposition, and then a Bragg grating is formed on a fiber core of a target optical fiber. Another optical fiber is used to capture part of optical signals reflected by the grating in the target optical fiber, thereby realizing the acquisition of the target optical fiber signals

In optical fiber communication, refractive index parameters of a fiber core, a cladding and a coating layer of an optical fiber are set differently, and due to inherent properties of materials and structures of the optical fiber, light can propagate in all directions when passing through an inhomogeneous medium, which is a scattering phenomenon of the light. When the signal light power transmitted by the optical fiber is small (at the moment, the dielectric polarization intensity and the electric field intensity of the optical field are in a linear relation), Mie scattering and Rayleigh scattering can be generated, and the frequency of scattered light generated by the two scattering effects is the same as that of incident light; brillouin scattering and raman scattering are also generated, and new frequency components appear in the scattered light. According to the huygens's secondary theory, light impinges on foreign particles in a homogeneous medium, which act as a new sub-wave source, continuing to emit spherical waves. The secondary waves emitted by the impurity particle secondary wave sources with the particle intervals much larger than the optical wavelength are all distributed irregularly and randomly, so that the secondary waves have no fixed phase relation. The secondary waves follow the incoherent superposition principle, and the interference cancellation phenomenon cannot occur, so that scattered light propagating in all directions occurs, and when the size of the secondary wave source particles is small, Rayleigh scattering is realized; when the secondary wave source particle size is relatively large, mie scattering is the result. Scattered light strongly correlated with the communication signal is the basis for external detection of the communication fiber.

Disclosure of Invention

In view of the above disadvantages, the present invention provides an apparatus and a method for acquiring a side scattering signal of an optical fiber. The device and the method use a signal acquisition structure device to reflect, converge and collect lateral scattered light of the optical fiber at a processed detection point of the communication optical fiber, an ambient light bottom noise isolation device reduces ambient light noise to the minimum, a high-performance photomultiplier module arranged on the signal acquisition structure device receives the scattered light signals, converts the scattered light signals into level signals and inputs the level signals to a data processing platform, and the data processing platform calculates the level signals to form digital waveforms which are displayed at a signal recovery output end. The transmission data in the optical fiber can be detected and extracted in real time in the optical fiber communication process, and the possibility is provided for external detection of optical fiber communication information in a hot running state.

The technical solution of the invention is as follows:

an apparatus for obtaining a side scatter signal from an optical fiber, comprising:

the signal acquisition device is used for acquiring scattered light of transmission signals in optical fiber communication;

the ambient light bottom noise isolation device is used for covering the signal acquisition device and enabling the signal acquisition device to be in a light-isolating and sound-insulating closed environment;

the data processing platform is used for receiving the analog signals transmitted by the signal acquisition structure device and outputting digital signals after processing;

and the signal recovery output end is used for receiving the digital signal transmitted by the data processing platform and outputting the shaped digital signal.

The signal acquisition device comprises a panel module, a concave reflector, an optical fiber clamp and a photomultiplier module, wherein the concave reflector, the optical fiber clamp and the photomultiplier module are arranged on the panel module; the optical fiber clamp is provided with a V-shaped groove for embedding the optical fiber with the coating layer and the cladding removed; the optical fiber clamp is arranged between the concave reflector and the photomultiplier module, the mirror surface of the concave reflector, the optical fiber and the detection lens end surface of the photomultiplier module are parallel, and the focal length f of the concave reflector₁Equal to the distance between the detection lens and the end face of the detection lens of the photomultiplier.

The concave reflecting mirror reflects and gathers scattered light with the scattering direction being the different end of the photomultiplier on the light signal receiving surface of the photomultiplier, and the photomultiplier converts the collected light intensity time signal into an analog level signal and inputs the analog level signal to the data processing platform.

The environment light bottom noise isolation device is composed of a shell body which is hermetically connected with five surfaces, the bottom of the shell body can be covered and buckled on the panel module, the shell body is provided with a mounting hole for the optical fiber and the detection lens of the photomultiplier module to pass through, and the periphery of the mounting hole is provided with a hinge, a hinge and a magnetic strip.

The periphery of the bottom of the shell is provided with a buckle used for being mounted and dismounted with the panel module.

The data processing platform intelligently calculates 0/1 signal judgment threshold values for detected analog signals, and the signal recovery output end outputs shaped digital signals after the above information is operated.

The method for detecting the signals by using the device for acquiring the side scattering signals of the optical fiber is characterized by comprising the following steps of:

1) initialization and installation: the communication optical fiber is used for transmitting information, a detection point of the communication optical fiber is selected, a coating layer and a cladding of the optical fiber are removed by a chemical or physical method, the optical fiber is embedded and fixed in a V-shaped groove of an optical fiber clamp on the signal acquisition structure device, the optical fiber is parallel to the end face of a detection lens of the high-performance photomultiplier, and the detection point is isolated by an ambient light bottom noise isolation device.

2) Collecting the scattered signals of the optical fiber: in the optical fiber communication process, scattered light signals escape from a detection point, and the scattered light signals opposite to the direction of the high-performance photomultiplier are reflected by the concave reflector and converged on the light signal receiving surface of the high-performance photomultiplier.

The diameter of the end face of the detection lens of the high-performance photomultiplier is l₀The core diameter of the optical fiber is d₀And the distance between the detector and the surface of the fiber core is d, the collection efficiency of the scattered light is as follows:

after the concave reflector (5) is used for reflecting and converging the signals of the scattered light (15) at the different end, the detection efficiency is improved as follows:

l₁is the diameter of the concave mirror and f is the focal length of the concave mirror.

3) And (3) shaping output of the signal: the high-performance photomultiplier module converts the collected light intensity signals into level signals to form analog waveforms related to light intensity, the data processing platform calculates the analog waveforms to obtain high-level threshold values and low-level threshold values, and the analog levels are shaped by the two threshold values to form digital square waves.

The maximum level value of the analog level signal W isV₁Low level signal is V₂Then high level threshold value V_HIs composed of

Low level threshold V_LComprises the following steps:

the shaped output of the digital signal (13) D is then:

if W≥V_H,D＝1；

if W≤V_L,D＝0.

and finally the output is shaped in the form of a digital signal.

The invention has the following advantages:

1. the invention can detect the transmission signal in real time in the optical fiber communication process;

2. the invention can realize quick assembly and disassembly;

3. the invention improves the collection efficiency of scattered light by the reflection and collection of the scattered signals at the different ends;

4. the invention provides possibility for external detection of optical fiber communication information in a hot running state.

Drawings

FIG. 1 is a schematic diagram of a signal acquisition structure device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of an apparatus and a method for acquiring a side-scattered signal of an optical fiber according to an embodiment of the present invention.

FIG. 3 is a schematic view of the signal acquisition structure device and the ambient light noise floor isolation device according to the embodiment of the present invention.

FIG. 4 is a diagram of an embodiment of the present invention, the light intensity being converted into an analog level signal.

FIG. 5 is a diagram of a pulse shaped digital signal output according to an embodiment of the present invention.

Detailed Description

The invention is further illustrated with reference to the following figures and examples. But should not be taken as limiting the scope of the invention.

Please refer to fig. 1, fig. 2, fig. 3, fig. 4, and fig. 5, which are schematic diagrams illustrating an apparatus and a method for acquiring a side scattering signal of an optical fiber according to an embodiment of the present invention. As shown in fig. 1, the concave reflector 5, the optical fiber clamp 6, and the high-performance photomultiplier module 7 are mounted on the panel module 16 to form the signal collecting structure 1. As can be seen from fig. 2, the signal acquisition structure device 1, the ambient light background noise isolation device 2, the data processing platform 3, and the signal recovery output terminal 4 form the whole system. As can be seen from fig. 3, the local black box formed in the closed environment forms the ambient light noise floor isolation device 2 having the function of removing the optical noise, and the hinges 8, the hinges 9, and the magnetic strips 10 mounted on the ambient light noise floor isolation device 2 can be conveniently and reliably mounted and dismounted. As can be seen from fig. 4, the detected scattered light 15 forms an analog level signal 12 via the high-performance photomultiplier module 7. As can be seen from fig. 5, the analog level signal 12 is output as a shaped digital signal 13 at the signal recovery output 4 via the data processing stage 3.

The following is a more detailed description of the present embodiment:

referring to fig. 1, fig. 1 is a schematic diagram of a signal acquisition architecture. The optical fiber 14 is fixed in a V-shaped groove of the optical fiber clamp 6 in an embedded manner, the processed optical fiber detection section is positioned in the center of the signal acquisition structure device 1, the detection section optical fiber 14 is parallel to the detection lens end face of the high-performance photomultiplier module 7, and meanwhile, the mirror face of the concave reflector 5 is parallel to the detection lens end face of the high-performance photomultiplier module 7. Focal length f of concave mirror 5₁Equal to the end face distance of the detection lens of the high-performance photomultiplier 7.

See fig. 2, 3. Fig. 2 is a general schematic diagram of an apparatus and a method for acquiring an optical fiber side scattering signal according to an embodiment of the present invention, including a signal acquisition structure apparatus, an ambient light noise floor isolation apparatus, a data processing platform, and a signal recovery output end. The signal acquisition structure device 1 is provided with a concave reflector 5, an optical fiber clamp 6 and a high-performance photomultiplier 7; the environment light background noise isolation device 2 with the function of removing the optical noise, and the hinge 8, the hinge 9, the magnetic strip 10 and the buckle 11 on the device can ensure that the device can be conveniently and reliably installed and disassembled; a data processing platform 3 which can intelligently calculate 0/1 signal judgment threshold value for the detected analog signal 12, and a signal recovery output terminal 4 which can arrange the detected information into digital signal 13 and output the signal. The signal acquisition structure device 1 uses the concave reflector 5 to improve the collection efficiency of the side scattered light 15 of the optical fiber 14. The concave reflector 5, the optical fiber clamp 6 and the high-performance photomultiplier 7 are fixedly mounted on the panel module 16. The optical fiber 6 with the coating layer and the cladding removed by a chemical or physical method is fixed in a V-shaped groove of the optical fiber clamp 6 in an embedded mode, and the scattering light 15 with the scattering direction being the different end of the high-performance photomultiplier 7 is reflected and collected on the light signal receiving surface of the high-performance photomultiplier 7 by the concave reflecting mirror 5. The high-performance photomultiplier 7 converts the collected light intensity time signal into an analog level signal 12 and inputs the analog level signal into the data processing platform 3. The ambient light background noise isolation device 2 constructs a temporary micro black box at a detection point of the optical fiber 14, eliminates the interference of ambient light noise and reduces the ambient light noise to the minimum; the hinges 8, the hinges 9, the magnetic strips 10 and the buckles 11 can enable the device to be conveniently and reliably mounted and dismounted. Detachably and fixedly mounting the processed detected optical fiber 14; the data processing platform 3 receives the analog level signal 12 from the high-performance photomultiplier 7, and intelligently calculates 0/1 signal judgment threshold values for the detected analog signals; the signal recovery output terminal 13 outputs the shaped digital signal 13 after the above information operation. Fig. 3 is a schematic structural disassembly diagram of the signal acquisition structure device and the ambient light background noise isolation device. The detection point of the optical fiber 6 is selected, the coating layer and the cladding layer of the optical fiber are removed by using a chemical or physical method, and after the optical fiber is fixed on the optical fiber clamp 6, the ambient light noise floor isolation device 2 is installed on the panel module 16. The optical fiber 14 and the high-performance photomultiplier module 7 pass through a mounting hole reserved on the ambient light background noise isolation device 2. After the signal acquisition structure device 1 and the ambient light bottom noise isolation device 2 are combined, the hinge 9 is closed, and the magnetic strips 3 on the signal acquisition structure device can be immediately combined and sealed when the hinge 9 is closed to form a local black box to eliminate ambient light interference; the buckle 11 is buckled downwards on the panel 16, and the installation reliability is guaranteed. In the process of optical fiber 14 communication, a scattered light 15 signal escapes from a detection point, and the scattered light 15 signal opposite to the direction of the high-performance photomultiplier module 7 is reflected by the concave reflecting mirror 5 and is converged on the light signal receiving surface of the high-performance photomultiplier module 7.

The diameter of the end face of the detection lens of the high-performance photomultiplier 7 is l₀The core diameter of the optical fiber is d₀And the distance between the high-performance photomultiplier module 7 and the surface of the fiber core is d, so that the collection efficiency of the scattered light is as follows:

after the concave reflector 5 is used for reflecting and converging the different-end scattered light 15 signals, the detection efficiency is improved as follows:

l₁is the diameter of the concave mirror 5 and f is the focal length of the concave mirror 5.

See fig. 4, fig. 5. Fig. 4 is a diagram of an analog level signal converted from light intensity, and fig. 5 is a diagram of a digital signal output after pulse shaping. The high-performance photomultiplier module converts the collected light intensity signals into level signals to form analog waveforms related to light intensity, the data processing platform calculates the analog waveforms to obtain high-level threshold values and low-level threshold values, and the analog levels are shaped by the two threshold values to form digital square waves.

The maximum level value of the analog level signal 12W is V₁Low level signal is V₂Then high level threshold value V_HIs composed of

Low level threshold V_LComprises the following steps:

the shaped output of the digital signal D (13) is then:

if W≥V_H,D＝1；

if W≤v_L,D＝0.

and finally the output is shaped in the form of a digital signal.

In summary, the invention uses refraction and reflection structures, and is matched with a high-performance photomultiplier module, so that the collection efficiency of the side scattering signals of the optical fiber can be improved. The ambient light bottom noise isolation device can form a temporary black box at a detection point to isolate external ambient light and reduce light noise to the minimum; the hinge, the magnetic strip and the buckle on the device can ensure that the device can be conveniently and reliably installed and disassembled, and the initialization of the equipment is completed on the premise of not interrupting the optical fiber communication process. The data processing platform and the signal recovery output end complete demodulation calculation of the optical signals and output recovered optical fiber transmission signals. The transmission data in the optical fiber can be detected and extracted in real time in the optical fiber communication process, and the possibility is provided for external detection of optical fiber communication information in a hot running state.

The above description is only one example of the present invention and should not be taken as limiting the invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.