Non-dispersive one-way signal amplification in sonic metamaterials
arXiv:2110.13219 · doi:10.1103/PhysRevApplied.17.024020
Abstract
Parametric amplification -- injecting energy into waves via periodic modulation of system parameters -- is typically restricted to specific multiples of the modulation frequency. However, broadband parametric amplification can be achieved in active metamaterials which allow local parameters to be modulated both in space and in time. Inspired by the concept of luminal metamaterials in optics, we describe a mechanism for one-way amplification of sound waves across an entire frequency band using spacetime-periodic modulation of local stiffnesses in the form of a traveling wave. When the speed of the modulation wave approaches that of the speed of sound in the metamaterial -- a regime called the sonic limit -- nearly all modes in the forward-propagating acoustic band are amplified, whereas no amplification occurs in the reverse-propagating band. To eliminate divergences that are inherent to the sonic limit in continuum materials, we use an exact Floquet-Bloch approach to compute the dynamic excitation bands of discrete periodic systems. We find wide ranges of parameters for which the amplification is nearly uniform across the lowest-frequency band, enabling amplification of wavepackets while preserving their speed, shape, and spectral content. Our mechanism provides a route to designing acoustic metamaterials which can propagate wave pulses without losses or distortion across a wide range of frequencies.
arXiv comment12 pages, 7 figures; v2: compressed images for faster rendering
References in corpus (22)
- Observation of non-Hermitian topology and its bulk-edge correspondence in an active mechanical metamaterial
- Floquet-Bloch theory and topology in periodically driven lattices
- Non-Reciprocal Wave Propagation in Spatiotemporal Periodic Structures
- Floquet engineering with quasienergy bands of periodically driven optical lattices
- Observation of nonreciprocal wave propagation in a dynamic phononic lattice
- Time-periodic stiffness modulation in elastic metamaterials for selective wave filtering: theory and experimental investigations
- Designing Perturbative Metamaterials from Discrete Models: From Veselago lenses to topological insulators
- Broadband Nonreciprocal Amplification in Luminal Metamaterials
- Experimental observation of temporal pumping in electro-mechanical waveguides
- Experimental observation of non-reciprocal band-gaps in a space-time modulated beam using a shunted piezoelectric array
- Nonlinear nano-electromechanical lattices for high-frequency, tunable stress propagation
- Exceptional rings protected by emergent symmetry for mechanical systems
- Dynamics and topology of non-Hermitian elastic lattices with non-local feedback control interactions
- Experimental Observation of Nonreciprocal Waves in a Resonant Metamaterial Beam
- One-way Phonon Isolation In Acoustic Waveguides
- Photonic Floquet media with a complex time-periodic permittivity
- A Bloch-based procedure for dispersion analysis of lattices with periodic time-varying properties
- Topological phases and nonreciprocal edge states in non-Hermitian Floquet Insulators
- Floquet topological system based on frequency-modulated classical coupled harmonic oscillators
- On the wave dispersion and non-reciprocal power flow in space-time traveling acoustic metamaterials
- Non-Hermitian elastic waveguides with piezoelectric feedback actuation: non-reciprocal bands and skin modes
- Stopping and reversing sound via dynamic dispersion tuning in a phononic metamaterial