Research On Key Technologies Of Micro-Optical Fiber Methane Gas Sensor

As one of the important sensing technologies,interferometric fiber optic sensors have been widely studied and applied in petrochemical,health monitoring,environmental monitoring,bio-medicine and other fields.In this paper,a high sensitive refractive index sensing device is fabricated by means of the strong evanescent field effect of micro-nano fiber and the interaction of the external environment,the micro-and nano-fiber devices are combined with nano-composite materials to realize highly sensitive and highly selective gas sensing.Firstly,The research significance and purpose of microfiber gas sensor are introduced,and the research status of microfiber gas sensor at home and abroad is summarized.The principle of the sensor is discussed by using the theory of mode interference and evanescent field.FDTD is further used to simulation the light transmission characteristics of tapered fiber,which provides a basis for the overall design of optical fiber sensors.Secondly,a tapered fiber sensor is designed and fabricated,and the measurement of the sensor is realized in the range of refractive index from 1.340 to 1.375.The experimental results show that the sensor blue-shifts with the increase of refractive index,and it has a good linear response relation to the refractive index response.Thirdly,a tapered fiber methane gas sensor based on SnO₂/graphene nanocomposite was designed and fabricated.In the range of 0-34.2%methane concentration,the transmission spectrum shifted from 1595.7 nm to 1597.6 nm,and changed 1.9 nm.The selective response characteristic of the sensor is studied.The results show that the sensor’s response to methane gas is 2.02 d Bm,that is,it has good selectivity to methane gas.Finally,a tapered fiber methane gas sensor based on Pd-SnO₂/rGO composite was designed and fabricated,and its response characteristics were studied experimentally.In the range of 0-7.2%methane concentration,the sensitivity coefficient of the sensor is 2.86.The relationship between the interference peak power at 1570 nm and the concentration of methane gas was fitted linearly with a linearity of 0.93.The response-recovery time of the sensor is 1 min and 3 min respectively.In summary,the combination of microfiber devices and nano-composite materials provides a new method for realizing highly sensitive and highly selective gas sensing.With the development of research,gas sensing technology based on micro-nano fiber will be widely developed and applied.