Enhanced compression of fundamental solitons in dispersion decreasing fibers due to the combined effects of negative third-order dispersion and Raman self-scattering

Abstract

Compression of ultrashort fundamental solitons in dispersion decreasing fibers (DDFs) with negative third-order dispersion (TOD) is investigated by solving the generalized nonlinear Schrödinger equation numerically. We show that, in contrast to the degradation of soliton compression due to the combined effects of positive TOD and Raman self-scattering (RSS), the combined effects of negative TOD and RSS can significantly enhance soliton compression in DDFs. The enhancement is due to RSS induced redshifting of the soliton wavelength and the negative TOD induced decrease of second-order dispersion toward the longer wavelength. It is also shown that for a given initial soliton width and a given ratio of input to output second-order fiber dispersion, there exist both an optimum DDF length and an optimum value of the negative TOD coefficient of the DDF at which the enhancement in soliton compression is maximum. We have also studied the dependence of the compression enhancement on both the initial soliton width and the ratio of input to output second-order fiber dispersion and found that the scheme works well for solitons with initial widths less than 3 ps.