Figure 1
Working principle and concept of the phase-to-intensity conversion.
(a) Due to the finite size of the amplifier, it provides a spectrum of effective wave vectors kp (green line). (b) Microwave photons with kp > 0 can split into co-propagating magnon pairs, leading to the formation of the signal and idler waves at one half of the pumping frequency. The solid dark blue line represents the spin-wave dispersion relation in the investigated Ni81Fe19 waveguide. (c) For a pumping field with fixed reference phase, schematically illustrated by the green line, the signal (black) and idler (red) waves are initially in-phase (solid lines). In this case, their interference is constructive. If the phase of the signal wave is shifted by π/2, the phase of the idler wave has to adjust its phase by −π/2 (dashed lines). Consequently, their interference becomes destructive. (d) Output intensity of the amplifier resulting from this interference mechanism. (e) Scheme of the experimentally investigated localized spin-wave amplifier together with its relevant dimensions. For details, see description in the main text.
