Research And Design Of Ultraviolet Low Loss Hollow Core Anti-Resonant Fiber

Ultraviolet(UV)fiber can be used in laser medicine,mechanical micromachining,UV communication,spectral applications and so on.Compared with traditional solid fiber,hollow core fiber(HCF)has larger core diameter,lower dispersion,higher damage threshold and wider transmission bandwidth,so it can be used as guiding medium to transmit high energy UV light.Therefore,it is of great importance to study the hollow core fiber with excellent transmission characteristics in UV band.In this paper,the structure of UV low loss hollow core anti-resonant fiber(HC-ARF)is designed and its transmission characteristics are researched.Firstly,the research background and the significance of this topic are introduced,and the research status of UV hollow core fiber with low loss and hollow core fiber with polarization characteristics is reviewed.The anti-resonance effect,coupling mechanism of suppression mode and transmission characteristics of hollow core fiber are described,and the relevant formulas of the full vector finite element method are introduced.Secondly,the anti-resonant layer is added to the UV HC-ARF cladding tube and the influence of changing the structural parameters on the transmission characteristics is studied by changing the diameter of core,the size and the thickness of cladding tube.According to the mode coupling theory,the coupling state is changed and the single mode characteristic is improved by shifting the position.In addition,the influence of the negative curvature boundary shape on the transmission characteristics is studied.Thirdly,the UV nested cladding tube HC-ARF is designed to study the influence of structural parameters on transmission characteristics.By changing the boundary shape of the negative curvature,mode coupling is enhanced to achieve better single mode characteristics.The influence of different cladding tube nesting types on transmission characteristics are investigated.Finally,the polarization characteristics of UV HC-ARF are studied.By changing the thickness of cladding tube at different positions,a single polarization HC-ARF based on the semi-ellipse and semi-circle cladding tube splicing is designed to achieve high birefringence characteristic.A kind of HC-ARF with eccentric core structure is proposed,which has strong resistance of bending and can maintain polarization in bending state.