The Research Of Key Technocology Of H₂S Gas Sensor Based On The Organic Polymer Optical Wavaguide

Hydrogen sulfide?molecular formula: H₂S?is one of the common by-products in the course of exploration and exploitation of oil and gas industry,which is strong toxic and corrosive.It is harmful to personnel,industrial equipment and environment.Therefore,the detection techniques of H₂S gas have attracted a large amount of research all over the world.Among all kinds of gas sensors,the optical H₂S gas sensor due to its passive,corrosion resistance,resistance to electromagnetic interference and other characteristics,is particularly applicable for long-distance online monitoring in specific occasion with the conditions of flammable long-distance,etc.Nowadays,the optical H₂S gas sensor mainly includes spectrum absorption type,evanescent field type,fluorescent type,etc.Some of them have the disadvantages of large volume,low sensitivity,etc.This thesis focus on high sensitivity and miniaturization H₂S gas sensor technology.A sensing method of H₂S gas detection based on an organic polymer optical waveguide is presented in this thesis,which use the H₂S sensitive organic polymer and the optical waveguide technique.Theoretical and experimental research of organic polymer optical waveguide gas sensor has carried out in this thesis.The results show that this method has the advantages of small volume,fast response,high sensitivity,easy integration,etc.The main work of this thesis includes:Firstly,according to the theory of optical waveguide effective index method and the effective refractive index of variational method,together with H₂S sensitive organic polymer optical properties,the model for designing and analyzing H₂S sensitive organic polymer optical waveguide is established.Optical transmission characteristics of waveguide structure is simulated.The single mode transmission structure ridge waveguide parameters has been confirmed,which laid a foundation for high sensitive organic polymeric ridge type optical waveguide H₂S gas sensor.Secondly,a kind of optical fiber F-P cavity structure of interferometric organic polymer hydrogen sulfide gas sensor is described.The F-P cavity is filled with H₂S sensitive organic polymer materials,according to the refractive index changes caused by concentration of H₂S gas changes to realize the high-precision interferometry.The theory model of optical fiber F-P cavity structure of H₂S gas sensor,the design of the structure of the optical path,signal processing algorithms and experiments has been studied.On one hand,the feasibility of implementation high sensitivity H₂S gas sensing is verified,on the other hand,with the experiment method,the relationship between the refractive index of the organic polymer and the gas concentration is obtained,which laid a solid foundation of M-Z structure interferometric gas sensor.Thirdly,the organic polymer optical waveguide H₂S gas sensors based on M-Z structure interferometer is designed.The structure of Y branch waveguide and M-Z structure waveguide interferometer is studied.The characteristic of M-Z structure organic polymer waveguide sensor is simulated.Through the simulation,according to the relationship between the gas concentration and the refractive index organic polymer material,the feasibility of realizing the gas concentration sensing by the M-Z structure organic polymer ridge waveguide is verified.Finally,the production process of M-Z structure organic polymer ridge optical waveguide is researched.On the basis of summarizing the conventional optical waveguide manufacture technology,the production process of organic polymer ridge optical waveguide is designed.Production of organic polymer ridge optical waveguide is completed by using photo etching technology.The results show that the production of organic polymer optical waveguide can satisfy the requirements of design size error,which has laid a solid foundation for further production of organic polymer M-Z structured optical waveguide.