Abstract: A fiber optical arrangement for the transmission, in a manner preserving its polarization, of light of a linear polarization state using an optical fiber having a linear birefringence of an amount sufficient to provide extensive decoupling of the polarization-degenerate modes of oscillation of the light that can propagate within the fiber. The amount of linear birefringence .beta. required for decoupling these modes of oscillation is achieved by winding the optical fiber in an elastically extended condition upon a winding form and fixing it thereon in this elastically extended state, the linear birefringence .beta.=.beta..sub.tc +.beta..sub.b being preferably three times greater than the intrinsic birefringence .beta..sub.i of the optical fiber. The fiber optical arrangement may be used within an interferometer for measuring pressures or, if mounted to rotate, within a Sagnac interferometer also for the exact measurement of rotations and rates of angular displacements.