Research On Sensing Technology Of New Hybrid Structure Fiber Optic Interferometer

As an important part of the technological innovation of the Internet of Things,sensing technology is an important means for human beings to expand their own perception,and it is also the basis for communication and computer transmission and processing of information in the information age.Sensors designed based on optical fiber technology have the advantages of high sensitivity,wide measurement range,high stability and strong anti-electromagnetic interference ability.These advantages make optical fiber sensors have an irreplaceable role in specific occasions,such as transportation,petroleum surveying,food safety,aerospace and other fields.With the continuous acceleration of the construction of the Internet of Things and Digital China,improving the mechanical strength and multi-parameter measurement capabilities of optical fiber sensors,reducing temperature crosstalk and system complexity in the sensing process,will become a new trend in the development of optical fiber sensing.This article mainly proposes and develops a variety of new hybrid optical fiber interferometers,which are used to improve the sensing performance in optical fiber sensing.The main innovative work of this paper is summarized as follows:(1)Aiming at the difficulty of measuring the liquid refractive index of traditional Michelson interferometer,this paper proposes a Michelson interferometer with end-encapsulated hybrid structure.The end encapsulation hybrid structure effectively protects the reflective end face of the sensor and improves the end reflectivity.The experimental results show that this sensor can measure the change of refractive index and temperature of the external liquid very well.In addition,the phaseshift tracking demodulation method in this article has the advantages of low noise and high resolution,which improves the accuracy of the sensing system.(2)In order to solve the cross-sensitivity problem caused by temperature in optical fiber sensing,a new hybrid optical fiber interferometer for dual-parameter measurement is made in this paper.Using the difference in the sensitivity of different troughs in the interference spectrum to temperature and refractive index,the simultaneous measurement of dual parameters is realized.Experimental research found that the temperature and refractive index sensitivity of this sensor can reach 47.7 pm/°C and-30.11 nm/RIU,respectively.At the same time,the sensor also has the advantages of simple structure manufacturing,stable interference spectrum and simultaneous measurement of multiple parameters.(3)The optical fiber sensor based on the tapered structure design has a fragile structure and has difficulties in practical applications.In order to improve the mechanical strength of the sensor,this paper proposes a hybrid Mach-Zehnder interferometer based on the three-microsphere structure.Three series-connected optical fiber microspheres are used as the excitation and coupling points of the sensor,which greatly improves the mechanical strength of the sensor itself.At the same time,this article also explored the sensor's perception performance of external temperature changes through experiments.Experimental research shows that the sensor has a sensitivity of 31.4 pm/°C in the temperature range of 25 °C to 95 °C.(4)In order to improve the multi-parameter measurement capability of the fiber interferometer,this paper proposes an all-fiber Fabry-Perot/Mach-Zehnder hybrid structure fiber interferometer.The hybrid sensing structure can achieve three-parameter measurement of temperature,lateral pressure and refractive index.Experimental studies have found that the sensor has a good linear response to lateral pressure,temperature and refractive index.In addition,the hybrid structure design can reduce crosstalk problems caused by temperature during multi-parameter measurement.In summary,the research in this paper has improved the sensing performance of the current optical fiber hybrid structure interferometer,and deepened people's knowledge and understanding of fiber optic sensors and hybrid structure fiber interferometers.These studies also contribute to the development and application of technologies such as optical fiber telemetry and optical fiber communication.