Observation of an optimum air-hole tapering for splicing between a conventional fiber and a photonic crystal fiber and the reduction of Fresnel reflection

摘要

We have already reported about an observation of a huge Fresnel reflection at a splicing point between a photonic crystal fiber (PCF) and a conventional fiber. This was caused by the difference of the refractive index in the claddings, which leads to a serious problem when utilizing PCF in optical communications. In this paper, the splicing characteristics between a PCF and a conventional fiber were measured in detail, and a splicing condition for suppressing the Fresnel reflection to below the Rayleigh scattering level was clarified. We also measured the cross-sectional structures of PCF near the splicing point by SEM, and a relation between reduction of the Fresnel reflection and air-hole form in the cladding of PCF was discussed.