Vector soliton states in optical fiber and their switching applications

Abstract

The characteristics of a nonlinear lightwave propagation in a birefringent fiber and their influences on the nonlinear switching device using the Sagnac type loop mirror are discussed. The polarization dynamics and nonlinear phase evolutions of the lightwave are studied by numerical method using the coupled nonlinear Schrödinger equations. The nonlinear phase evolution properties become important when studying the interferometric nonlinear switching devices although they are not so important when studying propagation dynamics only. It is newly found that a lightwave experiences different nonlinear phase accumulation depending on its input polarization state. As a dramatic example, a linearly polarized lightwave experiences 3/2 times more nonlinear phase accumulation than a circularly polarized one in an isotropic fiber. Nonlinear polarization dynamics both in the continuous wave(CW) and solitonlike pulse regimes, polarization mode delay(PMD) effect induced pulse splitting, and trapping by nonlinear effects are also discussed because they influence on the characteristics of the nonlinear switching devices. The birefringence effects on the self-switching devices using the nonlinear birefringent loop mirror are discussed. As a preliminary work, the birefringent loop mirror in the linear regime is discussed focusing on the total reflection and transmission conditions which are essential for high switching contrast of the nonlinear switching devices and on the PMD effect. Exploiting the PMD effect in the linear birefringent loop mirror, a new polarization independent optical differentiation is devised. In the nonlinear regime, a new scheme of the self-switching device using the nonlinear birefringence effect on the optical loop mirror is proposed. The switching principles of the schemes proposed by us and by Kuzin et al. are explained and compared. The switching characteristics of the proposed nonlinear birefringent loop mirrors(NBLM``s) for the CW and soliton...