Research On The Control Technology Of Stabilizing The Wavelength Of Light Source In Optical Fiber Gas Sensor

Fiber Optic Sensor is a new kind of sensor having developed since the1970s. It is mainly used to detect the poisonous gas, which is very dangerous also because it is easily to explode; It also could be used in examining and analyzing the gas needed to be known in people's daily life. So it could be said that the sensor works as the eyes and ears in the industry yield and people's daily-life.For the Fiber Optic Sensor, the ability of the light source directly and ultimately decides the performance of the whole sensor. So designing a perfect control system to automatically stabilize the output wavelength of the LD is important for pushing the technology of the whole Fiber Optic Sensor maturer. The control system investigated in this paper is mainly used in the Optical Fiber Gas sensor based on absorption spectrum. Aiming at the FOS's two serious problems——its badly stability and the poor floor level inspecting ability, the article discuss how to improve the LD's stability and at the same time lock the central wave-length of the LD's output spectrum to the absorption peak value of the gas molecule, which would enhance the gas absorption ability and ultimately improve the performance of the Fiber Optic Sensor.Firstly, on the base of widely reading and thoroughly summarizing the domestic and overseas correlative literature, the article introduces the wavelength-stabilizing technology of the Fiber Optic Sensor's light source. Besides, the article also investigates and compares several kinds of wavelength stabilizing technology popular at present and then chose a suitable control scheme for the system investigated in this paper.Secondly, the article analyses the characteristic of the Distributing Feedback laser diode(DFB-LD), which works as the light source in the Fiber Optic Sensor; and then improve the temperature controlling module and the feeding current stabilizing module, which are very important and comprised in the laser diode groupware, so that it could be properly used in this wavelength control system; on the base of the theory and technology analyzed and the control scheme having been chosen above, the article give the working theory and the structure chart of the wavelength stabilizing control system detailedly, and next accomplish the circuit design of each sub-module of this control system, mainly include the modulation module, the phase- shifting module, the magnifying technology of photoelectricity signal module and so on.Lastly, the article process experiment for the wavelength control system and give the curve and the analysis of the data getting from the experiment, which indicates that the control system could meet the demand of practically application.