Nonlinear propagation of various shape ultrashort pulses in a linearly birefringent single mode optical fiber. Numerical analysis

摘要

The results of numerical calculations of propagation of ultrashort hyperbolic secant, Gaussian and super Gaussian pusles in a linearly birefringent single mode fiber with input the polarization angle θ=15° and θ=30° are presented. From the performed calculations it follows, that the threshold amplitude of the initial pulse A_(th), after exceeding of which the soliton trapping effect occurs, depends on the shape of the initial pulse and is lowest for the hyperbolic secant pulse and highest for the super Gaussian pulse in the entire range of the birefringence parameter 0.1 < δ < 1.0, with the notion that values of A_(th) are slightly lower when the polarization angle θ=15°. The calculation results also indicate, that the threshold value of the birefringence parameter 8th, which designates the qualitatively different regions of soliton trapping, is dependent on the shape of the initial pulse as well. The highest value of δ_(th) was evaluated for the hyperbolic secant pulse, the lowest - for the super Gaussian pulse. The values of δ_(th) are very similar for input polarization angles θ=15° and θ=30° for each pulse.