Researchers at ETH Zurich have developed a method to make sound waves travel only in one direction, a breakthrough that could have significant implications for electromagnetic wave technology. The team, led by Professor Nicolas Noiray, has published their findings in Nature Communications.
In most cases, sound and light waves propagate in both forward and backward directions. However, in certain technical applications, it would be beneficial to have waves travel only in one direction, such as avoiding unwanted reflections of light or microwaves.
The ETH researchers’ approach involves using self-oscillations, which are periodic repetitions of a dynamical system’s behavior. They created a “circulator” that uses harmless self-sustaining aero-acoustic oscillations to allow sound waves to pass only in one direction without losses.
The team tested their design by sending a sound wave with a frequency of around 800 Hertz through the first waveguide and measuring how well it was transmitted to the second and third waveguides. As expected, the sound wave didn’t make it to the third waveguide. However, from the second waveguide (in the “forward” direction), a sound wave emerged that was even stronger than the original one.
The researchers believe their concept of loss-compensated non-rciprocal wave propagation could be applied to other systems, such as metamaterials for electromagnetic waves. This could lead to better microwave guidance in radar systems and the realization of topological circuits for future communications systems.
Source: https://phys.org/news/2024-09-implications-electromagnetic-technology.html