Study On Miniature Low-Pressure Fabry-Perot Interferometric Fiber-Optic Sensor

With the developments of fiber sensor,miniature fiber sensors have become important in the harsh environment,such as highly corrosive agents,electromagnetic interference(EMI) noise and limited space.In the domain of biomedical sense,invasive pressure measurement has played an important role in diagnosis and treatment.Diaphragm-based miniature Fabry-Perot cavity fiber pressure sensors have been shown to possess advantages of simple structure,small size,light weight,immunity to EMI noise,good stabilization and high sensitivity.In this dissertation,two types of miniature extrinsic Fabry-Perot interferometric fiber optic pressure sensors are desinged and fabricated.The theory and analysis of diaphragm based miniature F-P fiber pressure sensor are present in this dissertation,through of which,the model of the sensor is designed.A piece of hollow fiber with 175μm out diameter is fused directly onto a fiber tip to form F-P cavity.,and the PSQ diaphragm and quartzose diaphragm are used as the sensing elements,the entire size of the sensors are only 175μm.First,an entire quartz structure miniature fiber optic pressure sensor is fabricated by cleaving,fused splicing and etching.The pressure response of the sensor has been tested, showing a sensitivity of 41.09nm/MPa in the full pressure scale of 0-3.1MPa,and a system resolution of 681Pa.The temperature sensitivity of the sensor has also been tested under atmospheric pressure,exhibiting a weak temperature dependence of 1.07KPa/℃in the test temperature range from 20 to 140℃.Since it is hard to further decrease the thickness of the quartzose diaphragm,A polymer(PSQ) diaphragm is used instead to increase the sensitivity of the sensor.The pressure response of the PSQ diaphragm based sensor has also been tested under room temperature,showing a sensitivity of 1 886.85nm/MPa,in the full pressure scale of 0.1-2.1MPa,with a system resolution of 53Pa.That is very close to the requred resolution of biomedical application.This kinds of diaphragm based miniature fiber sensor can not only be widely used in biomedical areas such as blood presure detetion,cardiopulmonary pressure inspection,but also can be used in many industry areas,after futher optimization.