Fiber Grating Current Sensor Based On Tunable Fiber Laser

With the development of electric power industry, volume of electric power transmission system is increasing.and voltage higher and higher, so does the current.Traditional current sensor are not satisfied of the requirement of technique. Fiber current sensor will substitute for tradition current sensor, due of its good electric insulation, anti-jamming, small volume and high sensitivity. In many countries, research on fiber current sensor is development quickly.In the paper,a current sensor system cosist of the fiber laser ,GMM and fiber grating .The structure is of novel and original.Until the paper is achieved,It have not been reported to be related to current in country.In this design ,when the current of the current sensor is changing ,the GMM make FBG effective offset of wavelengh .And filter which is contronlled by micro-controller scanned fiber laser again and again.when the wavelengh of fiber laser is the same as the wavelengh of FBG ,the micro-controller go to the maximum of crrent through photo-electric transforming ,and then processing current signal, displaying the value of current.while the current go up from 1200mA to2300mA,the offset of center wavelengh of reflectance maximun go up along with linear augment of current .the value of offset is 0.336nm(1551.869,1552.04nm),In the paper ,main work is:We reseached and analysed actuality of fiber grating current sensor all over the earth.Finding the conclusion,fiber current sensor is the focus on reseach of the current sensor.The sensor will be wildly applied in current field in the future.The sensor is the focus on reseach of the current sensor.In the paper, tunable fiber laer is designed and achieved. The fiber is the basilic component of new type laser .The wavelengh of output is tuned by tunable filter, and then the output of laser is steady.when the power of output is 0 dBm,the value of stabilization is 0.01dBm for 10 minutes.It is able to work under long-playing and circumstance ,and power of output is large.For 12 hours,The tunable fiber laser is working,when the power of output is large .In the experiment, The PIN detection system is achieved ,including a low noise operational circuit,a A/D conversion and a micro-controller circuit.Detecting current is achieved through designing circuit,making print circuit board (PCB), programming micro-controller and debugging the whole system.Because the 24-bit converter is used,so the system has high sensitivity of the current and can process 0.002nm diversification of wavelengh.The current and wavelengh of fiber grating was experimented.According to the result of current sensor,we can know that when current is changing from 1200mA to 2300mA, A linear relationship is showed between the current and the offset of wavelengh. In the experiment,the precision of current is 6.55mA and the conclusion is summarized that the system consist of fiber laser ,GMM and fiber grating ,which is ideal way to resolve the current sensor.The experiment is operated on the basis of fiber grating current sensor about 21km.From the esperiment we can know that after the sensor system go through 21km transmission optical fiber, coming forth some fiber loss.In general, the result of the design of the system is credible and qualified for the designing demand.After studying the application in long-haul optical fiber monitoring sensing systems, we found the system optimal structure, According to the calculation of power distribution.At last, we summarize our study and give the future amelioration.And the current sensor system go to industrialization and practicality as soon as possible.