Soliton switching in elliptically birefringent single-mode fiber

The use of solitons has been proposed to eliminate pulse distortion in glass optical fiber switching devices. A switching design using ellipticlaly birefringent fibers that allow soliton propagation in the anomalous dispersion regime has been studied. In a birefringent fiber with ellipticity angle θ ≈ 35°, the self-coupling and cross-coupling between modes are identical, and the coupled nonlinear Schrodinger equation that governs the wave evolution possesses solitons. Solitons at one polarization, when interacting with an arbitrarily shaped pulse of the opposite polarization, will undergo uniform phase shifts and spatial displacements with no change in polarization or shape. This property of the solitons can be utilized to construct an all-optical switch. Preliminary results show that to obtain a phase shift of π for a 500-fs pulse with Δn = 2 × 10-4at λ0= 1.55 μm, an interaction length of 18 m is required.