Phase control of nonadiabatic parametric amplification of spin wave packets

Abstract

The influence of the phase shift between the signal and pumping wave on the process of parametric amplification of microwave spin wave pulses has been examined. The experiment was specifically made in the nonadiabatic regime, where the pumping field is strongly localized in a region on the order of the spin wave carrier wavelength. In this regime all previous experiments exhibited a strong random modulation (beating) of the amplified output signal. For a fixed phase shift between the signal and the pumping carrier waves the output signal was found to be stable, and no beating was observed. The amplitude of the amplified output pulse varies from the maximum value (corresponding to the maximum gain factor of 15 dB) to the minimum value (corresponding to almost no gain) when the phase shift between signal and pumping wave is changed. The measured phase interval between two consecutive minima in the phase dependence of the output power is equal to π.