Polarization characteristics of twisted single‐mode optical fibers

Abstract

Abstract Because of complexity in the refractivity distribution of the twisted optical fiber, the theoretical study on the polarization characteristics is difficult. Therefore an experimental investigation is made first. A simple model is proposed to explain generation of cross‐polarization components in case of linearly polarized wave incidence. A generalized tensor permittivity applicable to a twisted elliptic‐core fiber is derived. For the circular‐core fiber, the off‐diagonal elements of the tensor have the θ‐z component ϵθz only. For the elliptic‐core fiber, both the r‐θ components ϵrθ and the r‐z component ϵrz appear as the off‐diagonal components. The polarization characteristics are analyzed by combining the even and odd modes of HE11 mode which is a fundamental mode in the single‐mode optical fiber.