Fusion Splice Tecnique Of Hollow-core Photonic Crystal Fibers

In a hollow core photonic crystal fiber(HC-PCF),light is guided in the hollow air core with the merits of low transmission loss,low dispersion,low nonlinearity and high damage threshold.Among them,the hollow-core photonic bandgap fibers(HC-PBGF)have been widely used in optical sensors and optical communication as they can realize the minimum transmission loss in hollow-core optical fibers.In recent years,anti-resonant fibers(ARF)attracted intensive study as they exhibit a simple structure,a large degree-of-freedom in fiber design and new guidance mechanism.Compared with photonic bandgap fibers,anti-resonant fibers exhibit excellent optical properties in terms of low optical attenuation,broad transmission bandwidth and single modeness.It's suitable for sensors,nonlinear optics,high power laser generation and UV/mid-IR light transmission.However,when marching towards practical applications,the issue of fusion splice an photonic crystal fiber with a single mode fiber must be solved properly.In this paper,we studied the low-loss fusion splice between two hollow-core photonic crystal fibers and conventional single mode fiber by theoretical analysis,simulation and experiment.The main context is as follows.1.Mode mismatch is the main factor in those factors that impact the splice quality,which can be solved by intermediate fibers,thermal expanded core fibers,tapered fibers as well as controling the capillary collapse.As an efficient numerical method,the finite element method have been widely used in engineering applications and science research.Commercial multi-physical field thesis using finite element analyzing soft Matlab and Comsol was introduced to analyze the mode information.And latter the couple loss was calculated by correlative formulation.2.The thermal expanded core technology can enlarge the effective fiber core area and then expand mode field of optical fiber by heating the optical fiber core to allow the doped ion diffuse from core area to cladding area.Based on the simulation results,heating the core of single mode fiber by optical fiber tapering machine to realize mode match.Through setting a group of new parameters in special optical fiber splicing machine,the splice loss between HC-ARF and single mode fibers is reduced to 1 dB.3.Intermediate fiber is always used to match the mode field between two fibers.As a mature technology,the solid core fiber splicing technology can realize very low splice loss by efficient postprocessing and adiabatic splicing.Based on the simulation results,a low-loss fusion splice between a hollow-core anti-resonant fiber and a conventional single mode fiber is achieved by introducing a solid-core large mode aera fiber as an intermediate.Compared to the direct splicing technique,which yields a splice loss of 3 dB,the overall insertion loss using the intermediate fiber technique has a loss of only 0.844 dB.4.The research of photonic bandgap fibers started early and have made great progress in recent years.However,when marching towards practical applications,the issue of fusion splice a HC-PBGF with a single mode fiber,and with HC-PBGF itself must be solved properly.An low-loss fusion splice between a HC-PBGF and a conventional single mode fiber is achieved by introduction of an high V number intermediate fiber and thermal expansion core technique.Compared to the direct splicing technique with a splice loss of 1.4 dB,the overall insertion loss using the intermediate fiber technique has a loss of 0.73 dB.What's more,the self-splice technique of HC-PBGF is also presented.Through two steps of arc-splice,the splice strength of HC-PBGF to itself is guaranteed and the splice loss is reduced to 0.52 dB.