CN111397851A - OFDR multi-path optical fiber sensing system and method based on optical frequency comb technology - Google Patents
OFDR multi-path optical fiber sensing system and method based on optical frequency comb technology Download PDFInfo
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Abstract
本发明公开了一种基于光频梳技术的OFDR多路光纤传感系统和方法，包括：光频梳激光器、扫频发生器、单边带调制器、辅助干涉仪、主干涉仪、数据采集卡以及数据处理器；所述单边带调制器，用于接收所述光频梳激光器产生的频谱为离散谱线的脉冲光信号和所述扫频发生器输出的线性扫频的电信号，并调制为多波长同时扫频的复合扫频信号；所述辅助干涉仪，用于接收多波长同时扫频的复合扫频信号后产生外部时钟信号；所述主干涉仪，用于接收多波长同时扫频的复合扫频信号后产生拍频干涉信号；所述数据处理器，对所述数据采集卡中接收到的所述外部时钟信号和所述拍频干涉信号处理，获得多段光纤的同时测量结果。提升传感系统的空间分辨率和传感效率。
The invention discloses an OFDR multi-channel optical fiber sensing system and method based on optical frequency comb technology, comprising: optical frequency comb laser, sweep frequency generator, single sideband modulator, auxiliary interferometer, main interferometer, data acquisition a card and a data processor; the single-sideband modulator is used to receive the pulsed optical signal whose spectrum is discrete spectral lines generated by the optical frequency comb laser and the linearly swept electrical signal output by the sweep generator, and modulated into a composite frequency sweep signal of multi-wavelength simultaneous frequency sweep; the auxiliary interferometer is used to receive the composite frequency sweep signal of multi-wavelength simultaneous frequency sweep to generate an external clock signal; the main interferometer is used to receive multi-wavelength frequency sweep signals. A beat frequency interference signal is generated after the composite frequency sweep signal swept at the same time; the data processor processes the external clock signal and the beat frequency interference signal received in the data acquisition card, and obtains simultaneous multi-segment fibers. measurement results. Improve the spatial resolution and sensing efficiency of the sensing system.
Description
技术领域technical field
本发明属于光纤传感领域，涉及一种基于光频梳技术的OFDR多路光纤传感系统及方法。The invention belongs to the field of optical fiber sensing, and relates to an OFDR multi-channel optical fiber sensing system and method based on an optical frequency comb technology.
背景技术Background technique
光频域反射仪(OFDR)是一种具有高空间分辨率，高传感灵敏度和高定位精度等特点的分布式光纤传感器。在航空航天、精密仪器制造、建筑监测等领域具有极大地应用前景。在构建光频域反射仪的基本结构中，可调谐激光器是非常重要的一环，可调谐激光器的性能也对整体系统的各项参数指标产生了极大地影响，为了保证OFDR系统的传感参数质量，必须选用扫频线性度好，窄线宽，扫描范围大，扫描速度高的可调谐激光器。但是，这类高性能的可调谐激光器不仅输出功率较低，无法满足同时测量多段光纤的要求，并且价格十分昂贵，从而导致了OFDR传感系统的造价成本居高不下。Optical frequency domain reflectometry (OFDR) is a distributed fiber optic sensor with high spatial resolution, high sensing sensitivity and high positioning accuracy. It has great application prospects in aerospace, precision instrument manufacturing, building monitoring and other fields. The tunable laser is a very important part in the construction of the basic structure of the optical frequency domain reflectometer. The performance of the tunable laser also has a great impact on the parameters of the overall system. In order to ensure the sensing parameters of the OFDR system To improve the quality, a tunable laser with good frequency sweep linearity, narrow line width, large scanning range and high scanning speed must be selected. However, such high-performance tunable lasers not only have low output power, cannot meet the requirements of measuring multiple lengths of optical fibers at the same time, but are also very expensive, resulting in the high cost of OFDR sensing systems.
发明内容SUMMARY OF THE INVENTION
针对上述问题，本发明提供一种基于光频梳技术的OFDR多路光纤传感系统，以解决如上技术问题之一。In view of the above problems, the present invention provides an OFDR multi-channel optical fiber sensing system based on the optical frequency comb technology to solve one of the above technical problems.
根据本发明的第一实施方式，本发明提供的一种基于光频梳技术的OFDR多路光纤传感系统，包括：According to the first embodiment of the present invention, an OFDR multi-channel optical fiber sensing system based on optical frequency comb technology provided by the present invention includes:
光频梳激光器、扫频发生器、单边带调制器、辅助干涉仪、主干涉仪、数据采集卡以及数据处理器；其中，Optical frequency comb laser, swept frequency generator, single sideband modulator, auxiliary interferometer, main interferometer, data acquisition card and data processor; among them,
所述光频梳激光器，用于产生频谱为离散谱线的脉冲光信号；The optical frequency comb laser is used to generate a pulsed optical signal whose spectrum is discrete spectral lines;
所述扫频发生器，用于输出线性扫频的电信号和触发信号；The frequency sweep generator is used to output a linear frequency sweep electrical signal and a trigger signal;
所述单边带调制器，用于接收所述光频梳激光器产生的频谱为离散谱线的脉冲光信号和所述扫频发生器输出的线性扫频的电信号，将所述光频梳激光器产生的频谱为离散谱线的脉冲光信号和所述扫频发生器输出的线性扫频的电信号调制为多波长同时扫频的复合扫频信号；The single sideband modulator is used to receive the pulsed optical signal with discrete spectral lines generated by the optical frequency comb laser and the linearly swept electrical signal output by the frequency sweep generator, and the optical frequency comb The spectrum generated by the laser is a pulsed optical signal with discrete spectral lines and the linearly swept electrical signal output by the frequency sweep generator is modulated into a composite frequency sweep signal with multiple wavelengths swept at the same time;
所述辅助干涉仪，用于接收所述多波长同时扫频的复合扫频信号后产生外部时钟信号；The auxiliary interferometer is used to generate an external clock signal after receiving the composite frequency sweep signal of the multi-wavelength simultaneous frequency sweep;
所述主干涉仪，与所述辅助干涉仪并列设置，用于接收所述多波长同时扫频的复合扫频信号后产生拍频干涉信号；The main interferometer is arranged in parallel with the auxiliary interferometer, and is used for generating a beat frequency interference signal after receiving the composite frequency sweep signal of the multi-wavelength simultaneous frequency sweep;
所述数据采集卡，在所述触发信号的控制下接收所述外部时钟信号和所述拍频干涉信号；The data acquisition card receives the external clock signal and the beat frequency interference signal under the control of the trigger signal;
所述数据处理器，用于对所述数据采集卡中接收到的所述外部时钟信号和所述拍频干涉信号处理，获得多段光纤的同时测量结果。The data processor is configured to process the external clock signal and the beat frequency interference signal received in the data acquisition card to obtain simultaneous measurement results of multiple optical fibers.
优选的，所述主干涉仪包括N个干涉支路，N为大于等于2的自然数；Preferably, the main interferometer includes N interference branches, where N is a natural number greater than or equal to 2;
其中，每个所述干涉支路包括第四光纤耦合器c4、第五光纤耦合器c5、偏振控制器、环形器、测试光纤和光电探测器。Wherein, each of the interference branches includes a fourth fiber coupler c4, a fifth fiber coupler c5, a polarization controller, a circulator, a test fiber, and a photodetector.
优选的，所述N个干涉支路中的每个所述干涉支路，通过所述第四光纤耦合器c4分为两路，包括：Preferably, each of the interference branches in the N interference branches is divided into two circuits by the fourth optical fiber coupler c4, including:
第一路包括顺次连接的所述第四光纤耦合器c4、所述偏振控制器和所述第五光纤耦合器c5；第二路包括顺次连接的所述第四光纤耦合器c4、环形器、测试光纤以及所述第五光纤耦合器c5；其中，所述第四光纤耦合器c4与所述第五光纤耦合器c5之间存在光程差。The first path includes the fourth fiber coupler c4, the polarization controller, and the fifth fiber coupler c5 connected in sequence; the second path includes the fourth fiber coupler c4, the ring-shaped a test fiber, and the fifth fiber coupler c5; wherein, there is an optical path difference between the fourth fiber coupler c4 and the fifth fiber coupler c5.
优选的，所述辅助干涉仪，包括：第二光纤耦合器c2、第三光纤耦合器c3和光电探测器；Preferably, the auxiliary interferometer includes: a second fiber coupler c2, a third fiber coupler c3 and a photodetector;
其中，所述第二光纤耦合器c2与所述第三光纤耦合器c3分别以两种不同的光纤长度进行耦合后，再共同与所述光电探测器依次相连，所述第二光纤耦合器c2和所述第三光纤耦合器c3之间存在臂程差。The second fiber coupler c2 and the third fiber coupler c3 are respectively coupled with two different fiber lengths, and then jointly connected to the photodetector in sequence, and the second fiber coupler c2 and the third fiber coupler c3 has an arm length difference.
优选的，所述波长对应的频率范围Δf为0-1000GHZ。Preferably, the frequency range Δf corresponding to the wavelength is 0-1000GHZ.
优选的，所述光程差为0-50米。Preferably, the optical path difference is 0-50 meters.
优选的，所述臂程差为主干涉仪光程差两倍以上。Preferably, the arm path difference is more than twice the optical path difference of the main interferometer.
优选的，还包括：Preferably, it also includes:
阵列波导光栅，所述阵列波导光栅与所述第四光纤耦合器c4的另一端相连，所述主干涉仪通过所述阵列波导光栅分为N个干涉支路。An arrayed waveguide grating, the arrayed waveguide grating is connected to the other end of the fourth fiber coupler c4, and the main interferometer is divided into N interference branches by the arrayed waveguide grating.
优选的，还包括：Preferably, it also includes:
第一光纤耦合器c1，所述第一光纤耦合器c1的一端与所述单边带调制器相连，另一端分别与所述主干涉仪和所述辅助干涉仪相连，用于将所述多波长同时扫频的复合扫频信号分路给所述辅助干涉仪和主干涉仪。A first fiber coupler c1, one end of the first fiber coupler c1 is connected to the single sideband modulator, and the other end is connected to the main interferometer and the auxiliary interferometer respectively, and is used for connecting the multiple interferometers. The composite frequency swept signal whose wavelengths are swept at the same time is branched to the auxiliary interferometer and the main interferometer.
基于同一种发明思想，本发明还提供一种采用权利要求1-9任一所述系统进行多路光纤传感的方法，包括：Based on the same inventive idea, the present invention also provides a method for multi-channel optical fiber sensing using the system described in any one of claims 1-9, including:
所述光频梳激光器，产生频谱为离散谱线的脉冲光信号；The optical frequency comb laser generates a pulsed optical signal whose spectrum is discrete spectral lines;
所述扫频发生器，发出线性扫频的电信号；The frequency sweep generator sends out a linear frequency sweep electrical signal;
将所述光频梳激光器产生频谱为离散谱线的脉冲光信号和所述扫频发生器输出线性扫频的电信号输入单边带调制器中；The optical frequency comb laser generates a pulsed optical signal whose spectrum is discrete spectral lines and the frequency sweep generator outputs a linearly swept electrical signal into the single sideband modulator;
将通过所述单边带调制器进行调制，输出的多段波长同时扫频的扫频光输入至第一光纤耦合器c1中；inputting the swept-frequency light with the output multi-segment wavelengths swept simultaneously into the first fiber coupler c1;
将所述第一光纤耦合器c1中的多段波长同时扫频的扫频光分为两路，第一路进入所述辅助干涉仪中第二光纤耦合器c2和第三光纤耦合器c3，通过所述第二光纤耦合器c2和第三光纤耦合器c3以两种不同的光纤长度的耦合后出现光程差，形成外部时钟信号,进入光电探测器中；Divide the swept light of the multi-segment wavelengths in the first fiber coupler c1 into two channels, and the first channel enters the second fiber coupler c2 and the third fiber coupler c3 in the auxiliary interferometer, and passes through the auxiliary interferometer. The second optical fiber coupler c2 and the third optical fiber coupler c3 are coupled with two different optical fiber lengths, and an optical path difference occurs to form an external clock signal, which enters the photodetector;
第二路进入所述主干涉仪，经过阵列波导光栅，分为N路不同波长范围的扫频光信号在所述主干涉仪中被光纤耦合器c4分为两路，一路经过偏振控制器和到第五光纤耦合器c5，另一路通过环形器进入待测光纤中再回到所述第五光纤耦合器c5，所述两路出现光程差，形成拍频干涉信号输入所述光电探测器；The second channel enters the main interferometer, passes through the arrayed waveguide grating, and is divided into N channels of swept-frequency optical signals with different wavelength ranges. In the main interferometer, the optical fiber coupler c4 is divided into two channels. To the fifth fiber coupler c5, the other path enters the fiber to be tested through the circulator and then returns to the fifth fiber coupler c5, the two paths have an optical path difference, forming a beat frequency interference signal and inputting the photodetector ;
所述光电探测器将所述外部时钟信号和所述拍频干涉信号转换为电信号，接入到数据采集卡中，完成信号的采集；The photodetector converts the external clock signal and the beat frequency interference signal into an electrical signal, which is connected to a data acquisition card to complete signal acquisition;
数据处理器接收所述数据采集卡输出的电信号，经过处理，获得多段光纤的同时测量结果。The data processor receives the electrical signal output by the data acquisition card, and after processing, obtains the simultaneous measurement result of the multi-segment optical fibers.
本发明的有益效果The beneficial effects of the present invention
本发明将光频梳技术和光频域反射技术相结合。利用光频梳激光器作为信号源，通过和扫频信号发生器进行信号调制产生包含多波长范围同时线性扫频信号的连续光，利用这种复合线性扫频光作为光频域反射仪的扫频光源。将多波长范围的扫频光分离为多束扫频光，将不同波段的扫频光分别输入多根待测光纤中进行传感测试。The invention combines the optical frequency comb technology and the optical frequency domain reflection technology. The optical frequency comb laser is used as the signal source, and the continuous light containing the simultaneous linear frequency sweep signal in multiple wavelength ranges is generated by signal modulation with the frequency sweep signal generator, and the composite linear frequency sweep light is used as the frequency sweep of the optical frequency domain reflectometer. light source. The swept-frequency light in multiple wavelength ranges is separated into multiple beams of swept-frequency light, and the swept-frequency light in different bands is respectively input into multiple fibers to be tested for sensing testing.
本发明在光频域反射仪的结构中，通过波分复用的技术将多波长范围的扫频光分离为多束扫频光。In the structure of the optical frequency domain reflectometer in the present invention, the frequency-sweeping light in multiple wavelength ranges is separated into multiple beams of frequency-sweeping light through the technology of wavelength division multiplexing.
本发明充分利用了光频域反射仪的传感结构提升传感系统的空间分辨率和传感精度的同时，提升了光频域反射仪的传感效率，降低了利用光频域反射仪对多段光纤进行检测的成本。The invention makes full use of the sensing structure of the optical frequency domain reflectometer to improve the spatial resolution and sensing accuracy of the sensing system, and at the same time improves the sensing efficiency of the optical frequency domain reflectometer and reduces the use of the optical frequency domain reflectometer. The cost of testing multiple lengths of fiber.
附图说明Description of drawings
为了更清楚地说明本发明实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简要介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域的普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.
图1为本发明实施例中一种基于光频梳技术的OFDR多路光纤传感系统示意图；1 is a schematic diagram of an OFDR multi-channel optical fiber sensing system based on an optical frequency comb technology in an embodiment of the present invention;
图2为本发明实施例中一种OFDR多路分布式光纤传感原理示意图。FIG. 2 is a schematic diagram of an OFDR multi-channel distributed optical fiber sensing principle in an embodiment of the present invention.
具体实施方式Detailed ways
为了使本发明的目的、技术方案和优点更加清楚，下面将结合附图对本发明作进一步地详细描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其它实施例，都属于本发明保护的范围。In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.
下面结合附图详细说明本发明的优选实施例。The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
如图1所示，根据本发明的第一实施方式，本发明提供的一种基于光频梳技术的OFDR多路光纤传感系统，通过光频梳激光器产生多波长扫频信号叠加的信号源，解决了直接利用可调谐激光器进行探测时的功率受限问题，从而提升了OFDR系统接入传感光纤的数量，拓展了OFDR系统的可应用场景。As shown in FIG. 1 , according to the first embodiment of the present invention, the present invention provides an OFDR multi-channel optical fiber sensing system based on optical frequency comb technology, which generates a signal source that superimposes multi-wavelength swept frequency signals by an optical frequency comb laser. , which solves the problem of power limitation when directly using tunable lasers for detection, thereby increasing the number of sensing fibers connected to the OFDR system and expanding the application scenarios of the OFDR system.
本发明的一种基于光频梳技术的OFDR多路光纤传感系统示意图，如图1所示，整个OFDR系统由光频梳激光器、扫频发生器，单边带调制器，辅助干涉仪、主干涉仪、数据采集模块四部分组成，辅助干涉仪、主干涉仪均使用马赫-曾德尔干涉仪。A schematic diagram of an OFDR multi-channel optical fiber sensing system based on the optical frequency comb technology of the present invention, as shown in Figure 1, the entire OFDR system consists of an optical frequency comb laser, a sweep frequency generator, a single sideband modulator, an auxiliary interferometer, The main interferometer and the data acquisition module are composed of four parts. The auxiliary interferometer and the main interferometer all use the Mach-Zehnder interferometer.
光频梳激光器产生等频率间隔Δf＝1000GHZ的频谱为离散谱线的脉冲光，扫频发生器发出频率Δf＝1000GHZ线性扫频的电信号和触发信号，其扫频范围与光频梳输出信号谱线间隔相等，两路信号通过单边带调制后生成多段波长同时扫频的扫频光。其中，触发信号来控制采集数据的开启闭合时间。The optical frequency comb laser generates pulsed light with a spectrum of discrete spectral lines with equal frequency interval Δf=1000GHZ, and the sweep frequency generator sends out an electrical signal and a trigger signal with a linear sweep frequency of Δf=1000GHZ, and the sweep frequency range is the same as that of the optical frequency comb output signal. The spectral lines are equally spaced, and the two signals are modulated by the single sideband to generate sweeping light with multiple wavelengths sweeping at the same time. Among them, the trigger signal is used to control the opening and closing time of the collected data.
从单边带调制器输出的扫频光进入OFDR光路后被耦合器c1分为两路，一路进入辅助干涉仪，产生数据采集模块所用的外部时钟信号辅助信号采集，另一路进入主干涉仪，产生数据采集模块最终要采集的拍频干涉信号。主干涉仪与辅助干涉仪并列设置，耦合器c1的一端与单边带调制器相连，另一端分别与主干涉仪和辅助干涉仪相连，将所述多波长同时扫频的复合扫频信号分路给所述辅助干涉仪和主干涉仪。The swept-frequency light output from the SSB modulator enters the OFDR optical path and is divided into two paths by the coupler c1, one path enters the auxiliary interferometer to generate the external clock signal used by the data acquisition module to assist signal acquisition, and the other path enters the main interferometer. The beat frequency interference signal to be finally collected by the data collection module is generated. The main interferometer and the auxiliary interferometer are arranged side by side, one end of the coupler c1 is connected to the single sideband modulator, and the other end is connected to the main interferometer and the auxiliary interferometer respectively, and the composite frequency sweep signal of the multi-wavelength simultaneous frequency sweep is divided into to the auxiliary interferometer and the main interferometer.
主干涉仪，通过阵列波导光栅分为N个干涉支路，N为大于等于2的自然数，本实施例以N＝2为例进行描述。The main interferometer is divided into N interference branches by the arrayed waveguide grating, where N is a natural number greater than or equal to 2, and this embodiment is described by taking N=2 as an example.
在N个干涉支路中的每个干涉支路，包括第四光纤耦合器c4、第五光纤耦合器c5、偏振控制器、环形器、测试光纤和光电探测器。通过耦合器c4分为两路，一路包括顺次连接的光纤耦合器c4、偏振控制器和光纤耦合器c5；另一路包括顺次连接的光纤耦合器c4、环形器、测试光纤以及光纤耦合器c5；其中，光纤耦合器c4与光纤耦合器c5之间存在光程差为0-50米。扫频光进入主干涉仪后被光纤耦合器c4分为两路，其中一路光通过环形器进入测试光纤中，扫频光在待测光纤中传输产生与传播方向相反的后向瑞利散射信号，该信号通过环形器返回，与另一路经过偏振控制器的光信号在光纤耦合器c5处发生拍频干涉，产生的拍频干涉信号输入光电探测器中，被转化为电信号后被采集卡采集。Each of the N interference branches includes a fourth fiber coupler c4, a fifth fiber coupler c5, a polarization controller, a circulator, a test fiber, and a photodetector. It is divided into two paths by the coupler c4. One path includes the fiber coupler c4, the polarization controller and the fiber coupler c5 which are connected in sequence; the other path includes the fiber coupler c4, the circulator, the test fiber and the fiber coupler which are connected in sequence. c5; wherein, the optical path difference between the optical fiber coupler c4 and the optical fiber coupler c5 is 0-50 meters. After entering the main interferometer, the swept-frequency light is divided into two paths by the fiber coupler c4, one of which enters the test fiber through the circulator, and the swept-frequency light transmits in the fiber to be tested to generate a backward Rayleigh scattering signal opposite to the propagation direction. , the signal returns through the circulator, and beat frequency interference occurs with another optical signal passing through the polarization controller at the fiber coupler c5. The generated beat frequency interference signal is input into the photodetector, converted into an electrical signal, and collected by the acquisition card collection.
辅助干涉仪，包括：光纤耦合器c2、光纤耦合器c3和光电探测器；其中，光纤耦合器c2与光纤耦合器c3分别以两种不同的光纤长度相连，再与光电探测器相连，光纤耦合器c2和光纤耦合器c3之间存在臂程差为主干涉仪光程差的两倍以上，使辅助干涉仪产生的拍频信号频率为主干涉仪产生的拍频信号频率的两倍以上，从而满足奈奎斯特采样定理，保证采集信号不失真。Auxiliary interferometer, including: fiber coupler c2, fiber coupler c3 and photodetector; wherein, fiber coupler c2 and fiber coupler c3 are respectively connected with two different fiber lengths, and then connected with photodetector, fiber coupling The arm path difference between the c2 and the fiber coupler c3 is more than twice the optical path difference of the main interferometer, so that the frequency of the beat frequency signal generated by the auxiliary interferometer is more than twice the frequency of the beat frequency signal generated by the main interferometer, Thus, the Nyquist sampling theorem is satisfied and the collected signal is not distorted.
数据采集卡的一端与光电探测器相连，另一端与数据处理器相连，接收从光电探测器输出的电信号，经过数据处理器的处理，获得多段光纤的同时测量结果。One end of the data acquisition card is connected to the photodetector, and the other end is connected to the data processor, which receives the electrical signal output from the photodetector, and is processed by the data processor to obtain the simultaneous measurement results of multiple optical fibers.
本发明将光频梳技术和光频域反射技术相结合。利用光频梳激光器作为信号源，通过和扫频信号发生器进行信号调制产生包含多波长范围同时线性扫频信号的连续光，利用这种复合线性扫频光作为光频域反射仪的扫频光源。将多波长范围的扫频光分离为多束扫频光，将不同波段的扫频光分别输入多根待测光纤中进行传感测试。The invention combines the optical frequency comb technology and the optical frequency domain reflection technology. The optical frequency comb laser is used as the signal source, and the continuous light containing the simultaneous linear frequency sweep signal in multiple wavelength ranges is generated by signal modulation with the frequency sweep signal generator, and the composite linear frequency sweep light is used as the frequency sweep of the optical frequency domain reflectometer. light source. The swept-frequency light in multiple wavelength ranges is separated into multiple beams of swept-frequency light, and the swept-frequency light in different bands is respectively input into multiple fibers to be tested for sensing testing.
本发明在光频域反射仪的结构中，通过波分复用的技术将多波长范围的扫频光分离为多束扫频光。In the structure of the optical frequency domain reflectometer in the present invention, the frequency-sweeping light in multiple wavelength ranges is separated into multiple beams of frequency-sweeping light through the technology of wavelength division multiplexing.
本发明充分利用了光频域反射仪的传感结构提升传感系统的空间分辨率和传感精度的同时，提升了光频域反射仪的传感效率，降低了利用光频域反射仪对多段光纤进行检测的成本。The invention makes full use of the sensing structure of the optical frequency domain reflectometer to improve the spatial resolution and sensing accuracy of the sensing system, and at the same time improves the sensing efficiency of the optical frequency domain reflectometer and reduces the use of the optical frequency domain reflectometer. The cost of testing multiple lengths of fiber.
如图2所示，根据本发明的第二实施方式，本发明提供的一种基于光频梳技术的OFDR多路光纤传感方法。As shown in FIG. 2 , according to the second embodiment of the present invention, the present invention provides an OFDR multi-path optical fiber sensing method based on the optical frequency comb technology.
图2为一种基于光频梳技术的OFDR多路分布式光纤传感原理示意图，图中详细描述了系统结构和信号波形的构成，由光频梳激光器发出形为竖直线的，且每两条竖线之间为等频率间隔Δf＝1000GHZ的脉冲序列光，扫频发生器发出三角形的周期为T1，频率Δf＝1000GHZ的线性扫频信号，二者通过单边带调制器利用电能和带宽的调幅技术，将其调制为周期为Δt的多波长同时扫频的复合扫频信号。复合扫频信号经过光纤耦合器c1分为两路，一路进入辅助干涉仪，由于耦合器c2，c3之间以不同光纤长度进行连接，使得两路光纤存在臂程差，通常为主干涉仪光程差的两倍以上，故光信号在c3耦合器处发生拍频干涉，生成携带光源相位信息的拍频干涉信号即外部时钟信号，通过光电探测器PD转换为电信号后，作为采集卡时钟输入采集卡。Figure 2 is a schematic diagram of the principle of OFDR multi-channel distributed optical fiber sensing based on optical frequency comb technology. The figure describes the system structure and the composition of the signal waveform in detail. Between the two vertical lines is the pulse sequence light with equal frequency interval Δf=1000GHZ. The sweep frequency generator sends out a linear sweep signal with a triangular period of T1 and a frequency of Δf=1000GHZ. Amplitude modulation technology of bandwidth, modulate it into a composite frequency sweep signal of multi-wavelength simultaneous frequency sweep with period Δt. The composite frequency sweep signal is divided into two paths through the fiber coupler c1, and one path enters the auxiliary interferometer. Since the couplers c2 and c3 are connected with different fiber lengths, there is an arm distance difference between the two fibers, usually the main interferometer light. The optical signal is more than twice the path difference, so the optical signal has beat frequency interference at the c3 coupler, and the beat frequency interference signal carrying the phase information of the light source, that is, the external clock signal, is converted into an electrical signal by the photodetector PD, which is used as the acquisition card clock. Input capture card.
阵列波导光栅通常用于波分复用WDM系统中的光复用器，这些设备能够把许多波长的光复合到单一的光纤中，从而提高光纤网络的传播效率。本发明设置将另外一路经过阵列波导光栅AWG，分为N路不同波长范围的扫频光，波长扫描范围为Δf＝1000GHZ。每一路信号都输入搭建的一路相互独立的主干涉仪中。以图中画出的其中一路主干涉仪为例，信号在独立的主干涉仪中被耦合器c4分为两路，一路作为参考臂经过偏振控制器，到耦合器c5，另一路作为信号臂通过环形器进入待测光纤中，再由待测光纤回到环形器，然后到耦合器c5。信号臂中的后向瑞利散射信号与参考臂中的光信号之间存在光程差，光程差为传感光纤长度，通常为0-50m因此两路信号所携带光信号的频率不同，会在耦合器c5中发生拍频干涉。拍频信号输入光电探测器将干涉光信号转换为电信号，被数据采集卡采集。Arrayed waveguide gratings are usually used in optical multiplexers in wavelength division multiplexing WDM systems. These devices can combine many wavelengths of light into a single fiber, thereby improving the propagation efficiency of fiber networks. In the present invention, the other path passes through the arrayed waveguide grating AWG and is divided into N paths of sweeping light with different wavelength ranges, and the wavelength scanning range is Δf=1000GHZ. Each signal is input into a built-in main interferometer which is independent of each other. Taking one of the main interferometers shown in the figure as an example, the signal is divided into two channels by the coupler c4 in the independent main interferometer, one channel is used as the reference arm through the polarization controller, to the coupler c5, and the other channel is used as the signal arm. Enter the fiber under test through the circulator, and then return to the circulator from the fiber under test, and then to the coupler c5. There is an optical path difference between the backward Rayleigh scattering signal in the signal arm and the optical signal in the reference arm. The optical path difference is the length of the sensing fiber, usually 0-50m. Therefore, the frequencies of the optical signals carried by the two signals are different. Beat interference occurs in coupler c5. The beat frequency signal is input to the photodetector to convert the interference light signal into an electrical signal, which is collected by the data acquisition card.
另外，数据采集卡的工作状态受扫频发生器发出的另一种周期为t1的方波TTL触发信号来控制，此信号是一个直流信号，用于控制采集卡开始采集和结束采集的时间点，使每一路拍频干涉信号采集同步。当在0-t1内，该触发信号会控制开启采集卡，使采集卡处于采集数据的工作状态；t1-t2内，该触发信号会控制关闭采集卡，使采集卡处于非采集数据的状态；当t3-t4内，该触发信号会控制开启采集卡，使采集卡处于采集数据的工作状态。In addition, the working state of the data acquisition card is controlled by another square wave TTL trigger signal with a period of t1 sent by the sweep frequency generator. This signal is a DC signal, which is used to control the time point when the acquisition card starts and ends the acquisition. , so that the acquisition of each beat frequency interference signal is synchronized. When in 0-t1, the trigger signal will control the opening of the acquisition card, so that the acquisition card is in the working state of collecting data; in t1-t2, the trigger signal will control the closing of the acquisition card, so that the acquisition card is in a state of non-collecting data; During t3-t4, the trigger signal will control the opening of the acquisition card, so that the acquisition card is in the working state of collecting data.
经过数据处理器生成采集信号的功率谱信息，功率谱信息反映了整段测量光纤中的信号反射强度，获得多段光纤的同时测量结果。The power spectrum information of the collected signal is generated by the data processor, and the power spectrum information reflects the signal reflection intensity in the entire section of the measurement fiber, and the simultaneous measurement results of multiple sections of the fiber are obtained.
本发明将光频梳技术和光频域反射技术相结合。利用光频梳激光器作为信号源，通过和扫频信号发生器进行信号调制产生包含多波长范围同时线性扫频信号的连续光，利用这种复合线性扫频光作为光频域反射仪的扫频光源。将多波长范围的扫频光分离为多束扫频光，将不同波段的扫频光分别输入多根待测光纤中进行传感测试。The invention combines the optical frequency comb technology and the optical frequency domain reflection technology. The optical frequency comb laser is used as the signal source, and the continuous light containing the simultaneous linear frequency sweep signal in multiple wavelength ranges is generated by signal modulation with the frequency sweep signal generator, and the composite linear frequency sweep light is used as the frequency sweep of the optical frequency domain reflectometer. light source. The swept-frequency light in multiple wavelength ranges is separated into multiple beams of swept-frequency light, and the swept-frequency light in different bands is respectively input into multiple fibers to be tested for sensing testing.
本发明在光频域反射仪的结构中，通过波分复用的技术将多波长范围的扫频光分离为多束扫频光。In the structure of the optical frequency domain reflectometer in the present invention, the frequency-sweeping light in multiple wavelength ranges is separated into multiple beams of frequency-sweeping light through the technology of wavelength division multiplexing.
本发明充分利用了光频域反射仪的传感结构提升传感系统的空间分辨率和传感精度的同时，提升了光频域反射仪的传感效率，降低了利用光频域反射仪对多段光纤进行检测的成本。The invention makes full use of the sensing structure of the optical frequency domain reflectometer to improve the spatial resolution and sensing accuracy of the sensing system, and at the same time improves the sensing efficiency of the optical frequency domain reflectometer and reduces the use of the optical frequency domain reflectometer. The cost of testing multiple lengths of fiber.
最后应说明的是：以上实施例仅用以说明本发明的技术方案，而非对其限制；尽管参照前述实施例对本发明进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本发明各实施例技术方案的精神和范围。Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it can still be The technical solutions described in the foregoing embodiments are modified, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
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| CN113940631A (en) * | 2021-10-18 | 2022-01-18 | 中国科学院长春光学精密机械与物理研究所 | Optical coherence tomography system |
| WO2023170821A1 (en) * | 2022-03-09 | 2023-09-14 | 日本電信電話株式会社 | Device and method for measuring loss of plurality of optical fibers at once |
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