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 use their energy for amplification. They theoretically and experimentally demonstrated that this mechanism could simultaneously enhance non-reciprocity and compensate absorption. Real-world acoustic scattering experiments allowed them to observe non-reciprocal transmission of audible sound in a synchronization-based three-port circulator with full immunity against losses… read more. Open Access TECHNICAL ARTICLEÂ
Concept of synchronization-based loss-compensated non-reciprocal scattering in a circulator. Credit: Nature Communications volume 15, Article number: 7436 (2024)Â