  Wave-based data processing by spin waves and their quanta, magnons, is a
promising technique to overcome the challenges which CMOS-based logic networks
are facing nowadays. The advantage of these quasi-particles lies in their
potential for the realization of energy efficient devices on the micro- to
nanometer scale due to their charge-less propagation in magnetic materials. In
this paper, the frequency dependence of the propagation direction of
caustic-like spin-wave beams in microstructured ferromagnets is studied by
micromagnetic simulations. Based on the observed alteration of the propagation
angle, an approach to spatially combine and separate spin-wave signals of
different frequencies is demonstrated. The presented magnetic structure
constitutes a prototype design of a passive circuit enabling frequency-division
multiplexing in magnonic logic networks. It is verified that spin-wave signals
of different frequencies can be transmitted through the device simultaneously
without any interaction or creation of spurious signals. Due to the wave-based
approach of computing in magnonic networks, the technique of frequency-division
multiplexing can be the basis for parallel data processing in single magnonic
devices, enabling the multiplication of the data throughput.
