| Fiber optic Fabry-Perot(FP)sensors are used in many aspects of life,such as oil well pressure monitoring,aircraft air pressure monitoring and ocean humidity monitoring.Optical fiber FP pressure sensor has attracted more and more scholars’ attention in recent years because of its outstanding advantages: simple production process,high precision and high sensitivity.This paper mainly takes the optical fiber FP pressure sensor as the research object,and the main work is as follows:In this work,a Fabry-Perot barometric pressure sensor based on AB epoxy adhesive is proposed with high sensitivity at low pressure.The production process is as follows: according to the capillary phenomenon,the preparation of AB-type epoxy film layer is optimized by creatively using the adhesive transfer film method.The end of the capillary glass tube(Hermetically Coated Fiber(HCF)forms a layer of AB epoxy film with a thickness of 8.74 um.Further,the end face of single-mode fiber(SMF)and the end face of capillary glass tube with film layer are inserted into a thick glass tube from both sides,and the cavity length of 30 um can be accurately controlled by controlling the insertion distance,and FP interference cavity is formed between the capillary glass tube with an optimized AB epoxy film layer and the single-mode fiber,and finally the two ends of the glass tube are fixed with AB epoxy glue.Since the film is sensitive to external air pressure,this structure can be used for highly sensitive air pressure measurement.In this paper,the influence of curing time on the interference spectrum is also analyzed,and the experimental results show that with the increase of curing time,the interference spectrum will be blue-shifted,so it can be obtained that the decrease of the thickness of the AB epoxy film layer leads to the blue shift of the interference spectrum during the curing process.The experimental results show that when the external pressure is 0 k Pa～70 k Pa,the sensitivity of the fiber FP pressure sensor can be obtained by wavelength demodulation to be 257.79 nm/MPa.At the same time,the experimental process also proves that the optical fiber sensing structure has good humidity stability,and can be used for high-sensitivity measurement of low pressure and strength in the biomedical field.Studies have shown that the Vernier effect fiber FP pressure sensor can further effectively improve the sensitivity of the fiber optic sensor,and we add a reference cavity in parallel on the basis of the existing fiber FP sensing structure to form a Vernier effect between the reference cavity and the sensor.The experiment shows that when the air pressure range is 0 k Pa to 70 k Pa,the sensitivity of fiber FP air pressure sensing is3093.48 nm/MPa,which is 12 times the sensitivity of single-cavity FP sensor,which greatly increases the sensitivity of fiber optic FP pressure sensor. |
