VELOCITY CHARACTERISTICS OF MICROWAVE-MAGNETIC-ENVELOPE SOLITONS

The propagation properties of nonlinear microwave-magnetic-envelope (M ME) wave packets, or MME solitons. have been measured as a function of input microwave power in a 7.56 mu m-thick yttrium ion garnet film at 5 GHz with the static magnetic field of 1088 Oe parallel to the propa gation direction in the backward volume wave configuration. Input puls e widths ranged from 13 to 38 ns. While linear MME wave packets at low power levels propagate at the usual group velocity nu(g), the velocit y of MME solitons increases with input power and shows characteristic plateaus at values given by nu(s)((n))= nu(g) + kappa(n)D, where D is the dispersion coefficient and kappa(n)=(2n-1)pi/T nu(g) is an effecti ve wave-number parameter obtained from modulational instability consid erations. The parameter n=1, 2, 3, etc., indexes the soliton order and T is the width of the input pulse. in between the plateau regions, th e velocity increases mon-or-less linearly with power, and the slope of the response generally increases with the initial pulse width T. [S01 63-1829(98)02029-3].