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

Since Gao Kun proposed optical fibers,they have greatly changed human society.With the progress of the times,people’s requirements for the performance of optical fibers are becoming higher and higher.As a kind of hollow-core fiber,hollow-core antiresonance fiber has become a research hotspot in the field of hollow-core fiber due to its excellent characteristics such as low loss,wide transmission bandwidth,and single-mode transmission.In recent years,many new hollow-core antiresonance fibers have been proposed,and their applications have become more and more extensive.In this paper,some new hollow-core antiresonance fiber structures are designed.By finite element analysis method,the transmission characteristics are studied and the structural parameters are optimized,so as to obtain the hollow-core fiber structures with good performance.The main contents are demonstrated as follows:（1）A new negative curvature antiresonance hollow-core fiber structure is designed,whose cladding is composed of semi-circular tube and circular tube.Different nesting modes are considered,and the leakage loss and birefringence of these fiber structures are simulated by the finite element analysis method.It is found that the designed structure can achieve low loss and high birefringence characteristics,and the best nesting method is selected by comparison.The influence of structural parameters on the optical characteristics of the fiber structure is further studied.The simulation results show that the limiting losses of the x and y polarization fundamental modes of the optimized negative curvature antiresonance hollow-core fiber structure at 1.55μm are4.25×10^-4d B/m and 1.63×10^-3d B/m,respectively.The corresponding birefringence coefficient is 2.54×10^-5.（2）In order to reduce the side effects caused by structural defects of fiber,this paper proposes the idea of combining positive and negative curvature cladding to construct hollow-core fiber,and designs a partially negative curvature antiresonant hollow-core fiber structure.The fiber has multiple reflective layers and no transverse nodes.In this paper,the cladding mode in the positive and negative curvature cladding is coupled with the high order mode of the core to filter out the high order mode.Low-loss single-mode operation is realized under multiple resonant layers.The simulation results show that the leakage losses of the x and y polarization fundamental modes are less than 5.36×10^-3d B/m and 1.0×10^-3d B/m,respectively,in the wide band range of1.07μm¹.524μm.The figure of merit of the x and y polarization fundamental modes reached 2547 and 22596,respectively.