We analyze propagation in a nonlinear, birefringent optical fiber with twist. The results show that the polarization evolution is periodic, and they are applied to the analysis of a Sagnac interferometer. The period is calculated by using perturbation theory, and we find a condition for it to be independent of the initial polarization state. We derive a simplified set of equations to describe the nonlinear evolution of the phase. We give a useful way to visualize the behavior of the nonlinear optical loop mirror (as a function of birefringence, twist, length, and input polarization) in terms of the Poincaré sphere.
© 2001 Optical Society of America
(060.1810) Fiber optics and optical communications : Buffers, couplers, routers, switches, and multiplexers
(060.4370) Fiber optics and optical communications : Nonlinear optics, fibers
(190.4360) Nonlinear optics : Nonlinear optics, devices
Eugene A. Kuzin, Nikolai Korneev, Joseph W. Haus, and Baldemar Ibarra-Escamilla, "Theory of nonlinear loop mirrors with twisted low-birefringence fiber," J. Opt. Soc. Am. B 18, 919-925 (2001)