Femtosecond Pulse Shaping and the Fundamental Dark Soliton

Abstract

The technique of femtosecond pulse shaping provides unprecedented control of the amplitude and phase of utrashort optical pulses. One class of pulse shapes that can be fabricated by this technique is the so-called “dark pulse”. Dark pulses are a rapid dip or hole in a slowly varying intensity envelope. This pulse is of considerable interest because it resembles the formal solitary wave solution to the nonlinear Schrodinger equation in the positive group velocity dispersion region of optical fibers. This is true provided there is an abrupt π phase jump in the center of the dark pulse. We experimentally verify the existence of the fundamental dark soliton by propagating a 185-fsec dark pulse at a wavelength of 0.62 microns in a 1.4 m length of single mode fiber. At the appropriate power level the dark pulses propagate without broadening. Our measurements are in quantitative agreement with numerical solutions to the nonlinear Schrodinger equation.