Fabrication Of Optical Fiber Micro Pressure Sensor Based On Diaphragm

With the continuous development of optical fiber technology,the research of optical fiber in communication,sensing,information processing,industrial and medical fields has been widely concerned.Fiber optic technology can be used in information acquisition,information transmission,information processing and other aspects.Fiber optic sensors are mainly used to obtain information through optical fiber.After the study of semiconductor sensor,sensor,metal ceramic sensors and other sensors,with the development of sensor,people tend to study towards the direction of small,durable.In 1970 s,with the development of optical fiber technology,optical fiber sensors were invented.Optical fiber sensor is a sensor based on optical fiber for signal transmission and sensing measurement.Its basic principle is to transmit light signal from light source through optical fiber.The optical signal is modulated by some change of external environment(such as pressure,temperature,humidity,displacement,etc.)in the area to be measured.Changes(such as the phase,intensity,wavelength,frequency,etc.)of the light,transmit the modulated light signal to the photodetector through the optical fiber(both the other optical fiber can also transmit the light signal),and then demodulate the modulated light signal through the corresponding demodulation algorithm and obtain the corresponding environmental information.To the environmental parameters to be measured.In this paper,the sensing principle and type of EFPI optical fiber pressure sensors are introduced and analyzed in detail,and the EFPI sensors based on Fabry-Perot theory are introduced.After analyzing the common types of sensors,this paper analyzes and compares the different materials of EFPI optical fiber pressure sensor.A kind of optical fiber pressure sensor based on gold film is proposed.The optical fiber fusion machine is used to dissolve one end of the fiber and the capillary,and then we conglutinate the capillary and gold film by UV curing glue.The gold film used in this paper is made by the combination of photolithography and magnetron sputtering.The thickness of the diaphragm is easy to control.The length of the sensor cavity can be precisely demodulated by using SM125 wavelength scanning laser and discrete cross correlation demodulation algorithm.Experimental measurements show that the fiber EFPI sensor based on gold diaphragm has the sensitivity of 0.02nm/Pa at room temperature and in the range of pressure measurement of 0-25 kPa,with a good repeatability,and the maximum error is about 0.18% of the full range(25kPa).The sensor proposed in this paper will be applied prominently in the field of blood pressure measurement / photoacoustic imaging after controlling the thickness of the membrane.