Researchers at ETH Zürich have successfully developed a way to make sound waves propagate in only one direction, potentially paving the way for similar advancements in electromagnetic wave technology. The breakthrough comes from manipulating self-sustaining aero-acoustic oscillations inside a circulator, which creates a whistling sound that travels forward without backward reflection.
In their experiment, the team used three waveguides on the circulator to direct sound waves in one direction. Unlike normal situations where sound would propagate in both directions, this new approach allowed the researchers to isolate sound waves and prevent unwanted reflections. The results are promising, with stronger sound propagation in the forward direction without sacrificing any energy.
This innovation has significant implications for various applications, including protecting sources from echoes and inducing strong protection against obstacles or imperfections. The team believes that their concept of loss-compensated non-reciprocal wave propagation can be transferred to other systems, potentially leading to advancements in radar technology that utilize guided electromagnetic waves.
Source: https://www.iflscience.com/sound-made-to-travel-in-just-one-direction-by-physicists-76358