Study On Refractive Index Sensing And Optical Device Of I-shaped Optical Micro-nanofiber

In addition to the traditional optical waveguide function,micro-nano fiber?MNF?has many characteristics different from ordinary fiber,such as good diameter uniformity,atomic surface roughness,excellent flexibility,and strong mechanical strength.And when light propagates through the fiber,part of the light energy propagates outside the fiber in the form of an evanescent field.These properties of MNF make it a significant application in optoelectronic field such as fiber transmission,modulation,coupling,and sensing.At present,the application fields of MNF not only have the measurement of environmental parameters such as refractive index,temperature and humidity,but also the parameters such as gas concentration and substance concentration.The sensing mechanism of MNF is based on the interaction between light and matter.The I-shaped MNF used in this paper has a higher proportion of evanescent field due to its special structure,thus achieving a stronger interaction between light and matter,which can be used to fabricate a more sensitive MNF sensor.In this paper,the refractive index sensitivity and temperature sensitivity of the I-shaped MNF are tested.The maximum sensitivity of the refractive index-sensitive characteristic in the refractive index range of 1.395-1.400 is 4096nm/RIU.After PDMS encapsulation,due to its high thermo-optic coefficient,it has a temperature sensitivity of up to 5.56 nm/?in the temperature range of 25?to 40?in the temperature sensitivity test.In addition,the sensing part of the I-shaped MNF absorption sensing work replaces the structure of single-mode fiber?SMF?-I-shaped MNF-single-mode fiber with multimode fiber-I-shaped MNF-multimode fiber.The absorption baseline after replacement in the experiment is not only more smoothly,but also the detection limit of the concentration of the R6G solution can reach 1×10^-11mol/L.The I-shaped MNF used in this paper breaks the circular symmetry of the ordinary MNF light field distribution,obtains a stronger evanescent field,and realizes high refractive index sensitivity and temperature sensitivity.Compared with the common MNF sensor of the same type,I-shaped MNF sensor has greatly improved,which provides a good development opportunity for the performance improvement of the existing MNF sensors.