Research On Characteristics And Temperature Sensing Of Hollow-Core Negative Curvature Fiber

With the development of the communication and internet technologies,the people’s requirements for the performance of fiber are also increasing.Hollowcore negative-curvature fibers have gradually become a research hotspot due to the advantages of low loss,wide bandwidth,low nonlinear effect,high damage resistance threshold,and adjustable transmission wavelength.In addition,if the fiber has better single-polarization characteristics,it can be used in quantum computing,polarization-maintaining optical amplifiers,and single-polarization transmission.Therefore,how to realize the hollow-core negative-curvature fiber with single-polarization and low-loss characteristics and broaden the application scenarios are the problems to be solved.In this paper,the transmission mechanism,mode characteristics and structural parameters of hollow-core negative-curvature fibers are deeply studied.Three kinds of single-polarization and low-loss hollow-core negativecurvature fibers and temperature sensing based on hollow-core negative curvature fibers are designed and investigated.The work and innovation of this paper are summarized as follows:1.A semi-circular and semi-elliptical cladding structure hollow-core negative curvature fiber is designed.In the wavelength ranges of 1415 nm1423 nm,1427 nm-1429 nm,1462 nm-1466 nm,1492 nm-1494 nm,singlepolarization transmission is realized.The confinement loss in the wavelength range of 1414 nm-1421 nm is less than 0.5 dB/m,so the single-polarization and low-loss transmission are achieved.2.A U-typed cladding hollow-core negative curvature fiber was designed.In the wavelength ranges of 1525 nm-1527 nm,1540 nm,and 1549 nm-1551 nm,the single-polarization transmission is realized.The confinement loss at the wavelength of 1540 nm is 0.015 dB/m,so the single-polarization and lowloss transmission are achieved.3.A U-typed elliptical cladding hollow-core negative curvature fiber is designed,which realizes the single-polarization transmission in the wavelength range of 1549 nm-1552 nm.And the confinement loss at the transmission wavelength of 1550 nm is 0.00152 dB/m,the polarization loss ratio is as high as 25748,and the high-order mode loss ratio is 175.Singlepolarization and low-loss single-mode transmission is achieved at this wavelength.In addition,this fiber has a bending radius of 5 cm,which has good bending resistance.4.A six-tube cladding hollow-core negative-curvature fiber is designed.It is filled with the ethanol and gold wire to realize temperature sensing.The simulation results show that in the temperature range of 20℃-40℃,the sensitivity is 3.1 nm/℃,the resolution is 3.33×10^-3℃,and the fitting goodness of the fitting straight line between the sensing sensitivity and temperature is up to 0.999.In this paper,the fiber structure is used to meet the geometric asymmetry type to introduce single polarization.And the single polarization and low-loss hollow-core negative curvature fiber is studied.Taking advantage of the linear relationship between the refractive index of ethanol and the temperature and the characteristics of the anti-resonance tube’s inner wall coated with gold wire to excite surface plasmon resonance,the temperature sensing based on a hollow-core negative-curvature fiber is studied.The research results in this paper play important roles in promoting the development and application of hollow-core negative-curvature fibers.