Research On Microfiber Ring Resonator Sensing Based On Vernier Effect

With the development of optical fiber sensing technology,its devices have increasingly high requirements for size and sensitivity.Microfiber devices are widely used in the sensing field because of its small volume and strong interaction with surrounding media.The microfiber ri ng resonator with high sensitivity is one of the outstanding representatives.In order to improve the sensitivity of the sensor,the Vernier effect is also used in the sensing field with various optical structures,but there are some limitations and shortc omings in the previous research based on the Vernier effect.Therefore,it is of great theoretical significance and practical value to study the sensitivity amplification effect of Vernier effect in microfiber ring resonator sensing.On the one hand,this research starts with the theoretical analysis and simulation of the microfiber ring resonator,and studies the influence of several main structural parameters on its output spectrum.On the other hand,it is discussed the mathematical basis of the Vernier effect.By introducing the mathematical theorem of the periodic function,it is analyzed and systematically constructed the theoretical model of the general Vernier effect.Four mathematical forms are proposed to realize the Vernier effect: addition,subtraction,multiplication and division.Through the combination of the above two,methods of realizing the Vernier effect sensor by using the microfiber ring resonator in series-parallel structure and data operation are proposed.Single and series-parallel microfiber ring resonators are successfully fabricated by means of fused biconical taper method,non-truncated microfiber knotting technology and magnesium fluoride polishing plate substrate.Through the establishment of refractive index,temperature sensing theory and Vernier effect sensitization theory of microfiber ring resonator,sensing experiments are designed to verify the theory.In the experiment,we use the microfiber ring resonator to verify the multiplication Vernier effect of series structure,th e addition Vernier effect of parallel structure,and the division Vernier effect of single microfiber ring resonator by data operation.The experimental results are in good agreement with the theoretical analysis.Compared with the sensor without Vernier e ffect,the refractive index sensitivity can be magnified several to dozens of times.It is proved that the combination of Vernier effect and microfiber ring resonator has a significant amplification ability for the sensor sensitivity.The research shows th at the theoretical model of the general Vernier effect proposed in this paper has a wide range of applicability,which will play a guiding role in the realization of sensitivity amplification based on Vernier effect for sensors with various optical structu res and parameters.Including but not limited to the Fabry-Perot interferometer structure sensor,resonant cavity structure sensor,hybrid structure sensor,refractive index sensor,temperature sensor,humidity sensor,etc.