Cross-polarization modulation solitons in birefringent optical fibers

Abstract

First predicted by Zakharov and Mikhailov in 1987 [1], optical polarization domain walls were experimentally observed with counter-propagating beams in nonlinear isotropic optical fibers [2,3]. A polarization domain is a stable mutual arrangement of the beams' polarization [1]. A domain wall is a kink soliton which represents polarization switching between different domains [1-3]. With isotropic fibers, the interaction length is typically limited a few meters, which prevents continuous wave (CW) operation. In this work, we extend the theory of polarization domain solitons to both counter and copropagating beams of different frequency in highly birefringent (hibi), twisted and spun optical fibers [4]. We obtain new analytical domain wall soliton solutions whose propagation velocity may be controlled, and even stopped, by simply controlling the input relative intensity of the two beams. These findings may open the way to a new class of low-power, nonlinear optical data storage and buffer devices based on the dynamic control of polarization encoded information in fiber loop memories. Moreover, cross-polarization modulation interactions between wavelength channels have significant impact on polarization multiplexed wavelength-division-multiplexed (WDM) transmissions [5] and polarization-mode dispersion compensators [6]. Our analysis unveils the stable mutual polarization arrangements of WDM channels, and suggests novel polarization modulation schemes. Another interesting application is the lossless polarization attraction of an initially depolarized probe beam into the same polarization state of a co or counter-propagating pump wave [7]. In our work we investigate the practical use of polarization domain-based lossless polarizers for sub-W level pumps and signals using km-long hibi fibers.