<title>Depolarization features of wideband radiation in spun optical fibers with a high birefringence</title>

Abstract

The linear polarized wideband radiation depolarization taking place at propagation in the Spun fiber with a high embedded linear birefringence has been studied experimentally and theoretically. The theoretical model was developed on base of the conception of the spiral structure of linear birefringence axes, which is formed in the process of drawing out fiber at spinning preform. Using this model the expressions for calculating the degrees of the polarization of radiation on the fiber output were obtained at arbitrary fiber lengths and linear polarization azimuths on the fiber input. These expressions were obtained under the assumption that the radiation spectrum had a uniform and rectangular shape. The calculations and experiments showed that the Spun fiber is characterized by the depolarization length for which the degree of polarization decays from one to some residual level. As in the ordinary Hi-Bi fiber the depolarization length depends on the radiation spectrum wide and the value of the embedded linear birefringence, but in the Spun fiber that depends still on spin step. The specific feature of the Spun fiber is a desired nonconservation of the state of the linear polarization even at small lengths. The other feature which was discovered experimentally consists in the fact that the residual polarization is nearly circular at any azimuth of the input linear polarization.