Growth of Sharp Narrow Microwave Pulses due to Magnetostatic Wave Envelope Solitons

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High quality yttrium iron garnet (YIG) films have been grown on gadolinium gallium garnet (GGG) substrates by liquid phase epitaxial technology. The path length, where the propagation of magnetostatic wave (MSW) solitons is observed, is at most ten millimeters due to the loss of YIG even if we use a high quality YIG sample. To generate a 1-soliton pulse, we should supply higher power of microwave input than the value determined from the nonlinear Schrodinger equation (NLSE).Rectangular pulses are usually used as input in the MSW soliton experiments. The NLSE has been solved numerically. The numerical results show that if the loss of YIG is negligible, then we can always periodical breathing of pulses and that the pulses have become very sharp and narrow at some instant. However we take into accounts of the loss, the rectangular pulse is compressed into a pulse of which the pulse compression ratio is about three. We found that the pulse compression ratio become as large as a few tens if the wave form of input pulse is chosen appropriately, for example, parabolic or cosine pulse.The use of so-called soliton effects in a YIG film has been shown to be a promising technique for production of MSW pulses with at least as short width as 1 ns.To check this experimentally, we have proposed a method for designing wave form tailoring filters by using nonuniform transmission lines. The method is based on solving an inverse Zakharov-Shabat problem (IZSP) over a finite interval. The distribution of the characteristic impedance can be found from the reflection and transmission coefficients. The method is based on the deformation integrals. In practice, the length of transmission line is finite so the finiteness of interval is important. We proposed two methods for solving the IZSP.One method requires iteration, and the other solves the IZSP without iteration. The latter method is found to save computation time. Furthermore, it can be be applied to a wide range of potentials.