Phys.org September 6, 2024 Breaking the reciprocity of wave propagation is a problem of fundamental interest, and a much-sought functionality in practical applications, both in photonics and phononics. Although it has been achieved using resonant linear scattering from cavities with broken time-reversal symmetry, such realizations have remained inescapably plagued by inherent passivity constraints, which make absorption losses unavoidable, leading to stringent limitations in transmitted power. Researchers in Switzerland solved this problem by converting the cavity resonance into a limit cycle, exploiting the uncharted interplay between non-linearity, gain, and non-reciprocity. Strong enough incident waves could synchronize with these self-sustained oscillations and […]
Tag Archives: Sound waves
Physicists discover special transverse sound wave
Phys.org December 7, 2021 According to the researchers in Hong Kong the absence of shear force in the air, or fluids, makes sound waves longitudinal. Synthetic shear force may arise if the air is discretized into “meta-atoms,” whose collective motion can give rise to a transverse sound on the macroscopic scale. To implement this idea they designed micropolar metamaterial like a complex network of resonators. Air was confined inside the mutually connected resonators, forming the meta-atoms. Through theoretical calculations they showed that the collective motion of meta-atoms produces the shear force, which gives rise to the transverse sound with spin-orbit […]