Double-wave-front reversal of dipole-exchange spin waves in yttrium-iron garnet films

Abstract

The effect of double-wave-front reversal in the system of dipolar and dipole-exchange spin waves propagating in a ferrite film is studied experimentally and theoretically with the goal of development of a nonlinear microwave signal processor. In the proposed processor microwave signal pulse supplied to the input antenna excites in the ferrite film a long-wavelength dipolar spin wave (magnetostatic wave), which in the course of propagation is scattered on the film inhomogeneities and is transformed into short-wavelength long-lifetime dipole-exchange spin waves. Then, a sequence of two high-power double-frequency parametric pumping pulses, supplied to the film through an open dielectric resonator with a certain time delay between them, performs first, and then second, wave-front reversal for all the spin waves created by the input signal in the ferrite film. As a result of this double wave-front reversal process microwave output pulses with either reversed (input antenna) or nonreversed (output antenna) time profiles delayed by different time intervals appear at the antennae of the signal processor. The maximum delay time of the pulsed microwave input signal obtained as a result of the double-wave-front reversal was around 3μs with insertion losses below 25dB∕μs.