Study On Multi-parameter And Cross-free Fiber Sensor

For decades,fiber optic sensors have been given high promise as an emerging sensor.They are currently known to be used in structural health monitoring,biological environment measurement and other fields for their small size,light weight,high sensitivity,anti-electromagnetic interference.In this paper,the shortcomings and limitations of reported fiber optic sensors for fiber ultrasonic sensors and multi-parameter measurements are studied and discussed.Three models of fiber optic sensors for fiber ultrasonic sensors and multi-parameter measurements are proposed.And compared with the same type of sensors have been published.Aiming at the shortcomings of the existing fiber-optic ultrasonic sensors,such as low sensitivity,easy oxidation of the reflective diaphragm,inability to be applied to the harsh environment of strong acid and alkali and easy to be disturbed by the external environment,the operating point drifts,and this dissertation proposes an anti-environmentally disturbed all-fiber ultrasonic sensor with reflective diaphragm.The ultra-thin silica reflective diaphragm prepared by the arc discharge technology makes the sensitivity of the sensor high.The side-external environment of the sensor cavity is connected by the side-polishing single-mode fiber to lay the advantage of the sensor against environmental disturbance.At the same time,it does not affect the mechanical strength of the reflective diaphragm.The ultrasonic response of the sensor is as high as 293 m V / pa,and it responds well to irregular pulse signals with high waveform reduction.It has obvious advantages compared with the published research in the world.Aiming at the problem that the existing optical fiber sensor has a single physical quantity and is easily affected by other external variables,an all-fiber sensor with multi-parameter measurement is proposed.The sensor is based on the anti-resonance effect and makes full use of the large transmission spectrum caused by the anti-resonance effect.The characteristics of the free spectral range and high light intensity contrast measure external related physical quantities such as temperature and humidity by marking spectral drift and contrast change.The sensor has a temperature sensitivity of 24 pm / ? and a humidity sensitivity of-0.41 d B / %RH.Since the external physical quantities are separately demodulated by different parameters of the marked spectrum,the crosstalk between the two is extremely low while ensuring high sensitivity.Temperature and humidity is also a pair of related physical quantities,which are often accompanied by daily environment.Aiming at the shortcomings of the existing fiber curvature sensor,such as small measurement range and low mechanical strength,an all-fiber curvature sensor based on anti-resonance effect is proposed.The sensor is based on the anti-resonance effect and changes the intensity contrast of the marked transmission spectrum to the outside world.The change in curvature is measured and the change in curvature of the outside is measured by the change in intensity of the marker sensor.The sensitivity of the sensor is as high as 1.3 d B / m^-1,the measurement range is up to 30 d B.