Loss Induced Transmission Revival Based on Explicit Symmetry Violation

The introduction of lossy elements to a waveguide structure is conventionally associated with attenuation of its transmittances. In this research, we explore the elastodynamics of a one-dimensional, parity symmetric structure and reveal, both theoretically and experimentally, that upon appropriate excitation of the system, augmentation of a non-Hermitian, or damping, defect can trigger an unexpected revival in transmission. This phenomenon persists across the frequency spectrum and, specifically, occurs at eigenfrequencies corresponding to anti-symmetric modes of the underlying Hermitian system. Using a coupled mode theory framework, we demonstrate via perturbation theory and a Green's function approach, how a non-Hermitian perturbation can induce a disruption of the anti-symmetric mode nodal points and, subsequently, a revival in the transmission as the damping is increased. Our discoveries pave the way for innovative methods in full-spectrum detection of environmental variations.