CN101140220A - A multi-point optical fiber gas sensor system based on optical fiber buffer - Google Patents
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Abstract
一种基于光纤缓存器的多点瓦斯传感系统,有地址编码器,双波长光源,多点光纤传感网络,解调器。地址编码器产生不同监测点的地址码和读写控制信号;多点光纤传感网络的每个检测单元采用在光纤环路中引入气体吸收室的缓存器结构;可采用双环耦合全光缓存器与偏振型全光缓存器;在写信号控制下,将地址码光信号“写入”检测单元的光纤环路中,被瓦斯多次循环吸收;吸收后的光信号被“读出”送到解调器进行光电变换、与参考光比较、地址解码和数据处理,获得不同点的气体浓度,实现多点瓦斯监测。该系统通过改进吸收室结构、加装光放大器、偏振控制及1665nm波长器件的改进而获得有益效果,用于其他1665nm波长附近有吸收峰的气体监测。
A multi-point gas sensing system based on an optical fiber buffer includes an address encoder, a dual-wavelength light source, a multi-point optical fiber sensing network, and a demodulator. The address encoder generates address codes and read-write control signals for different monitoring points; each detection unit of the multi-point optical fiber sensor network adopts a buffer structure in which a gas absorption chamber is introduced into the optical fiber loop; a double-ring coupled all-optical buffer can be used With the polarization type all-optical buffer; under the control of the write signal, the address code optical signal is "written" into the optical fiber loop of the detection unit, which is absorbed by the gas for multiple cycles; the absorbed optical signal is "read" and sent to The demodulator performs photoelectric conversion, comparison with reference light, address decoding and data processing to obtain gas concentrations at different points and realize multi-point gas monitoring. The system obtains beneficial effects by improving the structure of the absorption chamber, adding an optical amplifier, polarization control and the improvement of the 1665nm wavelength device, and is used for monitoring other gases with absorption peaks near the 1665nm wavelength.
Description
技术领域 technical field
本发明涉及一种基于光纤缓存器的多点瓦斯气体传感系统,属于光纤传感系统以测量瓦斯气体浓度技术领域。The invention relates to a multi-point gas sensing system based on an optical fiber buffer, and belongs to the technical field of measuring gas concentration by optical fiber sensing systems.
背景技术 Background technique
能源紧缺已经成为制约我国目前的国民经济持续发展的重要因素。在一次能源(煤炭、核能、石油、天然气、风力、潮汐、太阳能)中,煤炭是我国最主要的一次能源,具有举足轻重的地位。但是,当前煤矿的安全状况却十分令人担忧。在各种矿难中,瓦斯爆炸位居第一,因此瓦斯监测技术一直是煤矿安全的重要技术。经过长期的研究和发展,已经研制出了多种系列的瓦斯检测仪器:如利用火焰的高度变化来检测瓦斯检定灯;基于光干涉原理的瓦斯检定器;、利用检测剂与被测气体进行化学反应时发生颜色变化(深浅或位移)来确定气体浓度的瓦斯检测管;利用被测气体与空气热导率之差来实现检测的热导式瓦斯检测仪;以及利用气敏材料表面吸附某些气体时电导率随浓度改变的气敏式瓦斯检测仪等,但由于它们存在很多缺点而没有获得应用。Energy shortage has become an important factor restricting the sustainable development of my country's current national economy. Among the primary energy sources (coal, nuclear energy, oil, natural gas, wind power, tide, solar energy), coal is the most important primary energy source in my country and plays a pivotal role. However, the current safety situation in coal mines is very worrying. Among various mine disasters, gas explosion ranks first, so gas monitoring technology has always been an important technology for coal mine safety. After long-term research and development, a variety of series of gas detection instruments have been developed: such as the use of flame height changes to detect gas test lamps; gas testers based on the principle of light interference; A gas detection tube that changes color (shade or displacement) during the reaction to determine the gas concentration; a thermal conductivity gas detector that uses the difference in thermal conductivity between the measured gas and air to achieve detection; and uses the surface of a gas-sensitive material to adsorb some Gas-sensitive gas detectors, etc., whose conductivity changes with the concentration of gases, have not been applied because of their many shortcomings.
目前广泛应用的是电化学热催化原理的甲烷检测仪,利用催化物,使低浓度甲烷在较低温度下持续燃烧(氧化),不同浓度的甲烷在催化燃烧时放出的热量不同,从而产生温度变化,因此可测量甲烷浓度。这种检测仪的优点是输出信号大,线性好,信号处理和显示都比较方便,电路和仪器的结构简化;测量时受环境条件影响很小,可以省去各种吸收剂;对甲烷以外的其它可燃气体(丁烷、戊烷等)也可以有所反应;容易实现自动连续监测。其缺点是抗中毒(硫化氢、有机硅蒸汽)性能较差;需要频繁校正(一周);测量范围一般在5%以下,浓度较高时,不但会出现激活现象,而且在10%以上时,还出现“双值性”(不同浓度出现相同读数)。At present, the methane detector based on the principle of electrochemical thermal catalysis is widely used. The catalyst is used to continuously burn (oxidize) low-concentration methane at a lower temperature. The heat released by different concentrations of methane during catalytic combustion is different, resulting in temperature changes, so methane concentrations can be measured. The advantage of this detector is that the output signal is large, the linearity is good, the signal processing and display are more convenient, the structure of the circuit and the instrument is simplified; the measurement is less affected by the environmental conditions, and various absorbents can be omitted; Other combustible gases (butane, pentane, etc.) can also react; it is easy to realize automatic continuous monitoring. Its disadvantages are poor anti-poisoning (hydrogen sulfide, organic silicon vapor) performance; frequent calibration (one week); measurement range is generally below 5%, and when the concentration is high, not only will there be activation phenomenon, but also when it is above 10%, "Double value" (same reading at different concentrations) also occurs.
国内已经有几种瓦斯安全监测系统,比如常州自动化研究所的KJ1,KJ2系统,长城科技公司的JK4系统,以及A1系统,KJ2000系统等,在煤矿安全生产方面发挥了重要作用。然而这些系统主要是利用先进的计算机技术和通信技术对监测系统进行改造,在信息的传输与采集上下功夫,对于最前端的瓦斯传感器并没有实质性的改进。多年来,瓦斯监测系统一致沿用基于电化学原理的瓦斯传感器,它必须采用远距离供电,本身就存在安全隐患,还存在中毒现象,寿命短。而且它的反应速度慢,当出现瓦斯突出时不能及时反映。多年来人们一直在寻找替代品和新的传感原理。大约在十年前,人们就提出了利用光纤制作瓦斯传感器。但是,十年来进展缓慢,至今没有一台光纤瓦斯传感器达到实用化水平在煤矿井下工作。There are already several gas safety monitoring systems in China, such as KJ1 and KJ2 systems of Changzhou Automation Research Institute, JK4 system of Great Wall Technology Company, A1 system, KJ2000 system, etc., which have played an important role in coal mine safety production. However, these systems mainly use advanced computer technology and communication technology to transform the monitoring system, and work hard on information transmission and collection. There is no substantial improvement on the front-end gas sensor. For many years, the gas monitoring system has consistently used the gas sensor based on the electrochemical principle. It must be powered by a long distance, which has potential safety hazards, poisoning, and short life. And its reaction speed is slow, can't reflect in time when there is gas outburst. Alternatives and new sensing principles have been sought for many years. About ten years ago, it was proposed to use optical fiber to make gas sensor. However, progress has been slow in the past ten years, and so far no optical fiber gas sensor has reached a practical level to work in coal mines.
光纤瓦斯传感的基本原理是基于气体对于光谱中特殊谱线吸收的比尔定律,即I=I0exp(-αCL),其中I0和I是光经过气体前后的光强,α是吸收系数,C是气体浓度,L是吸收长度。由上式可知,如果需要较高的检测灵敏度,必须要增大吸收系数或者吸收长度。如果利用光纤,还必须使吸收波长落于光纤的透光波长范围内。The basic principle of optical fiber gas sensing is based on Beer’s law that gas absorbs special spectral lines in the spectrum, that is, I=I 0 exp(-αCL), where I 0 and I are the light intensity before and after the light passes through the gas, and α is the absorption coefficient , C is the gas concentration and L is the absorption length. It can be seen from the above formula that if higher detection sensitivity is required, the absorption coefficient or absorption length must be increased. If an optical fiber is used, the absorption wavelength must also fall within the optical transmission wavelength range of the optical fiber.
瓦斯对于光的吸收波长有4个:3.43μm,6.522μm,3.3 12μm和7.658μm,它们均不能在石英光纤中透过,为此只能测定它们的谐波。过去对于光纤瓦斯传感器的研究,均使用1.31μm的波长,在这个波长上出现的是v2+3v3的组合谐波,吸收系数是非常低的。当气室长度达0.5m,即使气室的浓度达到爆炸上临界25%时,对1.3312μm波长的吸收损耗仅为0.03dB。这个损耗量级已经处于光源不稳定范围以下,要求测量很准是非常困难的。Gas has four absorption wavelengths for light: 3.43 μm, 6.522 μm, 3.3 12 μm and 7.658 μm, none of which can pass through the silica fiber, so only their harmonics can be measured. In the past research on fiber optic gas sensors, the wavelength of 1.31μm was used, and the combined harmonic of v 2 +3v 3 appeared at this wavelength, and the absorption coefficient was very low. When the length of the gas chamber reaches 0.5m, even if the concentration of the gas chamber reaches 25% of the upper critical limit of the explosion, the absorption loss for the wavelength of 1.3312μm is only 0.03dB. This level of loss is already below the unstable range of the light source, and it is very difficult to require accurate measurement.
为了获得较高的检测灵敏度,必须要较长的吸收长度,目前人们采用的气室长度为50cm左右。这意味着要将光从光纤中射出,经过50cm的吸收室后再汇聚到光纤中,这当然是十分困难的。虽然在原理上可行,但在技术上不可行。而且50cm的吸收长度对于一个传感头来说,体积过于庞大,受到环境的影响十分大。在一个充满了粉尘和水汽的矿井中,不可能获得实际应用。而且,当环境的瓦斯浓度变化时传感器气室的浓度也应该随之变化,但是过大的气室必将导致气室内的浓度与环境的气体浓度相差很大,或者在时间上滞后,降低了传感器的灵敏度和响应速度。因此,虽然光纤瓦斯传感器已经提出多年,许多研究机构报道了它们在实验室的研究结果,但是至今没有实用化,在恶劣的采煤工作面的狭小空间中难以使用。In order to obtain higher detection sensitivity, a longer absorption length is necessary. At present, the length of the gas chamber used by people is about 50 cm. This means that it is of course very difficult to send light out of the fiber, pass through a 50cm absorption chamber and then converge into the fiber. Although feasible in principle, it is not feasible technically. Moreover, the absorption length of 50cm is too bulky for a sensor head, which is greatly affected by the environment. In a mine full of dust and moisture, practical application is impossible. Moreover, when the gas concentration in the environment changes, the concentration in the gas chamber of the sensor should also change accordingly, but an excessively large gas chamber will inevitably lead to a large difference between the gas concentration in the gas chamber and the gas concentration in the environment, or lag in time, reducing the Sensitivity and response speed of the sensor. Therefore, although optical fiber gas sensors have been proposed for many years, and many research institutions have reported their research results in the laboratory, they have not been practical so far, and are difficult to use in the narrow space of the harsh coal mining face.
提高检测灵敏度和响应速度的途径有两个:(1)缩小吸收室的体积;(2)提高单位长度的吸收。为了缩小体积,但要保证有足够的吸收长度,唯一的方法是提高吸收次数。换言之,可以利用同一个光脉冲多次透过气室的方法,等效的增加吸收长度。There are two ways to improve detection sensitivity and response speed: (1) reduce the volume of the absorption chamber; (2) increase the absorption per unit length. In order to reduce the volume, but ensure sufficient absorption length, the only way is to increase the number of absorption. In other words, the same light pulse can be used to pass through the gas cell multiple times to increase the absorption length equivalently.
本发明的目的就是针对现有技术的不足而提出的一种新结构,即利用光脉冲在含有瓦斯吸收气室的光纤缓存器内多次循环吸收,大大缩小气室的长度,增加等效吸收长度;并利用编码调制技术,对每个缓存器进行“写入”与“读出”控制,实现用一个光源和解调系统对多个检测点进行复用。The purpose of the present invention is to propose a new structure aimed at the deficiencies of the prior art, that is, to use light pulses to absorb the gas absorbing gas chamber for multiple cycles in the optical fiber buffer, greatly reducing the length of the gas chamber and increasing the equivalent absorption. length; and use coding and modulation technology to control "writing" and "reading" for each buffer, so as to realize multiplexing of multiple detection points with one light source and demodulation system.
为了提高吸收率,本发明将吸收波长从v2+3v3的组合谐波转移到v3的2次谐波(1.665μm),其吸收系数增加一个数量级,可以使气室长度从50cm缩短为5cm。从而大大提高检测的灵活性,便于实用化。In order to improve the absorption rate, the present invention transfers the absorption wavelength from the combined harmonic of v 2 +3v 3 to the second harmonic of v 3 (1.665 μm), and its absorption coefficient increases by an order of magnitude, which can shorten the length of the air chamber from 50cm to 5cm. Therefore, the flexibility of detection is greatly improved, and it is convenient for practical application.
为了进一步提高检测精度,本发明采用双波长方式,一个为吸收波长,另一个为参考波长。二者经过同一个光路,除了吸收损耗不同而外,其它光路损耗均相同,通过差分比对,可以获得很高的检测灵敏度。In order to further improve the detection accuracy, the present invention adopts a dual-wavelength mode, one is the absorption wavelength, and the other is the reference wavelength. The two pass through the same optical path, except for the absorption loss, the other optical path losses are the same, and a high detection sensitivity can be obtained through differential comparison.
发明内容 Contents of the invention
本发明的目的是通过如下的技术方案实现一种基于光纤缓存器的多点光纤瓦斯传感系统,它由一个地址编码器,一个双波长光源,一个多点光纤传感网络,以及一个解调器所组成,用于高精度、高灵敏度、实时监测煤矿井下多点的瓦斯气体浓度。The purpose of the present invention is to realize a kind of multi-point optical fiber gas sensor system based on optical fiber buffer by the following technical scheme, it consists of an address encoder, a dual-wavelength light source, a multi-point optical fiber sensor network, and a demodulator Composed of devices, it is used for high-precision, high-sensitivity, real-time monitoring of gas concentration at multiple points in underground coal mines.
地址编码器产生用于不同监测点的串行地址码,并对双波长光源进行调制,同时产生用于对不同监测点“写入”和“读出”的控制信号。The address encoder generates serial address codes for different monitoring points, modulates the dual-wavelength light source, and generates control signals for "writing" and "reading" different monitoring points.
双波长光源发出的光经过地址编码器调制后,送入多点光纤传感网络。The light emitted by the dual-wavelength light source is modulated by the address encoder and sent to the multi-point optical fiber sensor network.
多点光纤传感网络包括多个检测单元,每个单元采用光纤型全光缓存器的结构,并在光缓存器的光纤环路中增加了一个气体吸收室。光缓存器包括用于缓存光信号的光纤环路以及环路中的放大器、偏振控制器、波分复用耦合器等附件,一个用于“写入”与“读出”的非线性元件,以及一个气体吸收室。每个检测单元在地址编码器的控制下,将载有本检测点地址信息的光信号,“写入”本单元的光纤环路中,并多次循环;每次循环都通过一次吸收室,从而被瓦斯多次吸收。然后,在地址编码器的控制下,将被瓦斯多次吸收的光信号“读出”,并送入解调器。The multi-point optical fiber sensor network includes a plurality of detection units, each unit adopts the structure of the optical fiber type all-optical buffer, and a gas absorption chamber is added in the optical fiber loop of the optical buffer. The optical buffer includes an optical fiber loop for buffering optical signals, amplifiers in the loop, polarization controllers, wavelength division multiplexing couplers and other accessories, a nonlinear element for "writing" and "reading", and a gas absorption chamber. Under the control of the address encoder, each detection unit "writes" the optical signal carrying the address information of the detection point into the optical fiber loop of the unit, and circulates it multiple times; each cycle passes through the absorption chamber once, Thus being absorbed by gas many times. Then, under the control of the address encoder, the optical signal absorbed by the gas is "read out" and sent to the demodulator.
解调器把收到的载有不同地址与气体吸收信息的光信号进行光电变换后,再与参考波长的光信号进行比较,进行地址解码和数据处理,获得不同吸收气室的气体浓度参数,从而实现对多点瓦斯浓度的实时监测。不同的码型对应于不同的监测点,当它们到达同一个解调器时很容易把它们区分出来。The demodulator performs photoelectric conversion on the received optical signal carrying different addresses and gas absorption information, and then compares it with the optical signal of the reference wavelength, performs address decoding and data processing, and obtains the gas concentration parameters of different absorption gas chambers. Realize real-time monitoring of multi-point gas concentration. Different patterns correspond to different monitoring points, and it is easy to distinguish them when they arrive at the same demodulator.
本发明的技术方案同样适用于在1665nm波长附近有光吸收峰的其他气体的传感与监测。The technical scheme of the invention is also applicable to the sensing and monitoring of other gases with light absorption peaks near the wavelength of 1665nm.
本发明的有益效果是:The beneficial effects of the present invention are:
(1)基于光纤缓存器的多点光纤瓦斯气体传感系统,充分结合现代光通信领域的高新技术和传感领域的高新技术,包括光编码技术,全光缓存器技术,光纤传输技术,调制解调技术,多路复用技术,用于煤矿井下瓦斯气体分布式检测,对多个位置的瓦斯气体浓度进行高灵敏度、高精度、实时监测,为保障煤矿安全提供重要依据。(1) The multi-point optical fiber gas sensor system based on the optical fiber buffer fully combines the high-tech in the field of modern optical communication and the high-tech in the field of sensing, including optical coding technology, all-optical buffer technology, optical fiber transmission technology, modulation Demodulation technology and multiplexing technology are used for distributed detection of methane gas in coal mines. It can monitor the concentration of methane gas in multiple locations with high sensitivity, high precision and real-time, providing an important basis for ensuring the safety of coal mines.
(2)基于光纤缓存器的多点光纤瓦斯传感系统的技术效果还可以通过以下手段得到提高。(2) The technical effect of the multi-point optical fiber gas sensing system based on the optical fiber buffer can also be improved by the following means.
第一,改进气体吸收室的组成和结构,提高吸收室性能,降低光路传输损耗,可以提高气体对光的吸收效率,减小噪声,从而提高传感系统的性能。First, improving the composition and structure of the gas absorption chamber, improving the performance of the absorption chamber, and reducing the transmission loss of the optical path can improve the light absorption efficiency of the gas and reduce noise, thereby improving the performance of the sensing system.
第二,改进光纤环形腔的结构,包括在光纤环中加装光放大器,以补偿光路损耗。由于在煤矿井下现场的部分光纤线路,环境恶劣情况复杂,可能引起附加损耗与自激噪声等不稳定因素,对光纤传输特性和环形腔性能影响较大。因此,改进光纤环路的结构以及控制方式可以提高传感系统的性能。Second, improve the structure of the fiber ring cavity, including installing an optical amplifier in the fiber ring to compensate for the loss of the optical path. Due to the harsh environment of some optical fiber lines in underground coal mines, it may cause unstable factors such as additional loss and self-excited noise, which have a great impact on optical fiber transmission characteristics and ring cavity performance. Therefore, improving the structure and control mode of the optical fiber loop can improve the performance of the sensing system.
第三,改进或者选取更优化的码型与调制、复用方式,能改善全光缓存器中光开关的控制信号与时间同步性能,提高分布式光纤传感技术的灵活性和准确性,从而提高传感系统的性能。Third, improving or selecting a more optimized code pattern, modulation, and multiplexing method can improve the control signal and time synchronization performance of the optical switch in the all-optical buffer, and improve the flexibility and accuracy of distributed optical fiber sensing technology, thereby Improve the performance of sensing systems.
第四,选取双波长光源时,它的两个工作波长既要能够区分出吸收波长和参考波长,又要能够尽量接近,以保证切实起到参考作用,而且它们的波长和光功率都应该稳定。因此,选取优质的功率稳定的双波长光源,可以提高传感器的性能。Fourth, when selecting a dual-wavelength light source, its two working wavelengths must be able to distinguish between the absorption wavelength and the reference wavelength, and must be as close as possible to ensure that they can serve as a reference, and their wavelength and optical power should be stable. Therefore, selecting a high-quality dual-wavelength light source with stable power can improve the performance of the sensor.
第五,采取快速偏振稳定技术,可以改善多个传感头(吸收室)联合工作的时候的干涉效果,从而提高传感系统的性能。Fifth, adopting fast polarization stabilization technology can improve the interference effect when multiple sensing heads (absorbing chambers) work together, thereby improving the performance of the sensing system.
第六,传感器系统信号处理部分的功能改善,也有利于提高传感器的技术效果。Sixth, the improvement of the function of the signal processing part of the sensor system is also conducive to improving the technical effect of the sensor.
第七,传感器系统其它部分的功能改善,选用与瓦斯气体二次谐波吸收峰对应波长(1665nm)配套的双波长连续激光器、耦合器、环行器、滤波器、隔离器等相关光器件并提高性能,都有利于提高传感器系统的技术效果。Seventh, the functions of other parts of the sensor system are improved, and the relevant optical devices such as dual-wavelength continuous lasers, couplers, circulators, filters, isolators, etc. matching with the second harmonic absorption peak of gas gas (1665nm) are selected and improved. performance, are conducive to improving the technical effect of the sensor system.
附图说明 Description of drawings
图1为基于光纤缓存器的多点光纤瓦斯传感系统结构示意图;Fig. 1 is a schematic structural diagram of a multi-point optical fiber gas sensing system based on an optical fiber buffer;
图2为基于双环耦合全光缓存器的多点光纤瓦斯传感系统的结构示意图;Fig. 2 is the schematic structural diagram of the multi-point optical fiber gas sensing system based on the double-ring coupled all-optical buffer;
图3为基于偏振型全光缓存器的多点光纤瓦斯传感系统的结构示意图。Fig. 3 is a schematic structural diagram of a multi-point optical fiber gas sensing system based on a polarization-type all-optical buffer.
具体实施方式 Detailed ways
下面结合实施案例和附图对本发明做进一步说明。The present invention will be further described below in combination with examples of implementation and accompanying drawings.
实施例1:采用双环耦合全光缓存器的多点光纤瓦斯传感系统;Embodiment 1: A multi-point optical fiber gas sensor system using a dual-ring coupled all-optical buffer;
如图1所示,基于双环耦合全光缓存器的多点光纤瓦斯传感系统由一个地址编码器1,一个双波长光源2,一个由多个双环耦合全光缓存器组成的多点光纤传感网络3,以及一个解调器4所组成。多点光纤传感网络3如图2所示,它由多个双环耦合全光缓存器组成,每个双环耦合全光缓存器,包括一个环行器5,一个平行排列3X3耦合器6,左右两个光纤环路7与8,吸收室9以及一个非线性元件10。As shown in Figure 1, the multi-point optical fiber gas sensor system based on dual-ring coupled all-optical buffers consists of an
地址编码器1针对不同的监测点设定不同码型,对图2中1665nm的双波长光源2进行调制,并产生用于对不同监测点“写入”和“读出”的控制信号Pctl1,Pctl2和Pctl3。双波长光源2发出的光经过地址编码器1的调制后,送入多点光纤传感网络3的第一个监测点A所使用的双环耦合全光缓存器的环行器5,然后进入平行排列3×3光纤耦合器6的中间端口。3×3耦合器将这个信号分为两路,从耦合器右侧的上下两端口平均输出,进入光纤右回路7。非线性元件10接收到来自于地址编码器1的“写入”控制信号Pctl1,将本监测点A对应的地址码“写入”环形腔,进入左回路8。在左回路8中安置了一个气体吸收室9,这个地址信号就被瓦斯气体吸收一部分,然后再返回到右回路7。这样,这个码型的脉冲就在这两个回路组成的环形腔中反复绕圈,并多次被瓦斯气体所吸收,直至另一个控制信号“读出”信号将它从吸收回路读出来为止。读出的信号从平行排列3×3耦合器6左侧中间端口输出,再次经过环行器5离开第1个监测点A的光缓存器,穿过后面的监测点B和监测点C的环行器并最终到达解调器4。The
解调器4收到的载有不同地址与气体吸收信息的光信号先进行光电变换后,然后进行地址解码和数据处理,获得不同吸收室的气体浓度参数,从而实现对多点瓦斯浓度的实时监测。The optical signals carrying different addresses and gas absorption information received by the demodulator 4 are first subjected to photoelectric conversion, and then address decoding and data processing are performed to obtain gas concentration parameters of different absorption chambers, thereby realizing real-time monitoring of gas concentrations at multiple points. monitor.
非线性元件10在这里的作用是产生非线性相移,因此能够在1665nm波长产生非线性相移的器件都可以实现这个功能,具体可以使用普通光纤、高非线性光纤、光子晶体光纤、半导体光放大器以及电吸收调制器等。The function of the nonlinear element 10 here is to generate a nonlinear phase shift, so any device capable of generating a nonlinear phase shift at a wavelength of 1665nm can realize this function. Specifically, ordinary optical fibers, highly nonlinear optical fibers, photonic crystal fibers, and semiconductor optical fibers can be used. Amplifiers and electroabsorption modulators, etc.
实施例2:采用偏振型全光缓存器的多点光纤瓦斯传感系统;Embodiment 2: A multi-point optical fiber gas sensor system using a polarization-type all-optical buffer;
如图1所示,基于双环耦合全光缓存器的多点光纤瓦斯传感系统由一个地址编码器1,一个双波长光源2,一个由多个偏振型全光缓存器组成的多点光纤传感网络3,以及一个解调器4所组成。多点光纤传感网络3如图3所示,每一个监测点使用一个偏振型全光缓存器,并在缓存器的光纤环路中安置一个气体吸收室6。因此每个偏振型全光缓存器,都包括一个非线性元件5,吸收室6、一段光纤环路7。这里指的光纤环路7包括一段光纤以及改善环路性能的附件,比如偏振控制器、放大器等。As shown in Figure 1, the multi-point optical fiber gas sensor system based on dual-ring coupled all-optical buffers consists of an
地址编码器1针对不同的监测点设定不同码型,对图2中1665nm双波长光源2进行调制,并产生用于对不同监测点“写入”和“读出”的控制信号。双波长光源2发出的光经过地址编码器1的调制后,送入多点光纤传感网络3。它首先到达第一个监测点A所使用的偏振型全光缓存器的非线性元件5。非线性元件5接收到来自于地址编码器1的“写入”信号,产生偏振旋转,将监测点A对应的地址码“写入”光纤环7,并经过气体吸收室6,这个地址信号就被瓦斯气体吸收一部分,然后再返回非线性元件5。由于这时没有新的控制信号到来,所以这个地址信号的脉冲就在这个光纤环路中反复绕圈,并多次被瓦斯所吸收。当另一个控制信号“读出”信号到来时,非线性元件5将再次使光信号发生偏振旋转,从而使它从吸收回路读出来。读出的信号经过后面的监测点B和监测点C的非线性元件5时,由于没有相应的“写入”信号,所以将直接通过它们。以此类推,这个信号将最终达到解调器4。其它监测点的信号流程与此类似。解调器4收到的载有不同地址与气体吸收信息的光信号后,先进行光电变换并和参考光的信号进行比较,然后进行地址解码和数据处理,获得不同吸收室的气体浓度参数,从而实现对多点瓦斯浓度的实时监测。The
非线性元件5在这里的作用是产生非线性偏振旋转,因此能够在1665nm波长产生非线性旋转的器件都可以实现这个功能,具体可以使用普通光纤、高非线性光纤、光子晶体光纤、半导体光放大器以及电吸收调制器等。The function of nonlinear element 5 here is to generate nonlinear polarization rotation, so any device that can generate nonlinear rotation at a wavelength of 1665nm can realize this function, specifically ordinary optical fiber, highly nonlinear optical fiber, photonic crystal optical fiber, semiconductor optical amplifier can be used and electroabsorption modulators.
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