The Research Of Humidity Sensor Base On Fiber-Optic Fabry-Perot Cavity

Relative humidity values as an important reference index of environmental characteristics it at many places are very necessary to the precision of measurement。In daily life, production activities and the growth and survival of plants and animals, are closely linked with the surrounding environment humidity, household appliances, transportation, medical, meteorology, industrial and agricultural need for humidity measurement. Arsenal storage warehouse where flammable substances using electronic hygrometer is very dangerous, but most of today's market presence hygrometer humidity has high shortcomings is measurement accuracy. Fiber F-P sensor is based on the principle of F-P interference to produced. All-optical signal sensing signal can be transmitted without attenuation of long-range, applicable in harsh environment measurement, optical interferometer, high resolution features with high precision is expected to achieve the relative humidity measurement.This paper, based on fiber-optic F-P interference principle in research and development of optical fiber end surface coating F-P cavity humidity sensor. With ceramic ferrule fixed fiber end, in order to increase the film adhesion on the fiber end face. Coated silver film/porous silicon film/silver film on the fiber end face, silver film to form a two-tier structure of F-P interference in the middle of the porous silicon film as element of moisture-sensitive fiber-optic FP moisture sensor probe, and experiments on the production of the humidity test humidity sensor performance verification. The content of this thesis for the completion of the following studies:(1)Fiber F-P interference theoryAnalysis of multi-beam interference theory, high-finesse fiber-optic F-P cavity finesse optical theory, and loss characteristic analysis of low-finesse fiber-optic F-P interference.(2) fiber F-P cavity productionSimple and efficient method of making optical fiber FP cavity is disturbed optical fiber FP cavity sensor to the main practical, this use of magnetron sputtering with a ceramic ferrule in a fixed reflection coating, through the study of their production process to increase and improve the sensor Probe for. (3) The humidity sensitive properties of thin filmsIn addition to the sensor detection precision F-P cavity effect of reflection outside the thin films are moisture-sensitive thin film effect and its characteristics, this use of porous silicon thin films of moisture sensitive components have a high humidity response.(4) Humidity Sensor Experiment testDesign of fiber-optic FP cavity humidity sensor test system, set up experimental testing of the sensor optical broadband light source incident on the infrared spectral response and the time of the incident monochromatic laser light source when the optical power changes, and test results to analyze the data obtained humidity sensor characteristics.