Non-reciprocal and highly nonlinear active acoustic metamaterials

Non-reciprocal and highly nonlinear active acoustic metamaterials.

Unidirectional devices that pass acoustic energy in only one direction have numerous applications and, consequently, have recently received significant attention. However, for most practical applications that require unidirectionality at audio and low frequencies, subwavelength implementations capable of the necessary time-reversal symmetry breaking remain elusive. Here we describe a design app...

Tunable active acoustic metamaterials

We describe and demonstrate an architecture for active acoustic metamaterials whose effective material parameters can be tuned independently over a wide range of values, including negative material parameters. The approach is demonstrated experimentally through the design and measurement of two types of unit cells that generate metamaterials in which either the effective density or bulk modulus...

Nonlinear Acoustic Metamaterials for Sound Attenuation Applications

Soliton generation in active nonlinear metamaterials

We demonstrate experimentally a mechanism of the soliton generation in nonlinear active metamaterials. Our meta-structure consists of a ring resonator formed by a microwave amplifier loaded with a left-handed transmission line. We demonstrate a variety of nonlinear effects not described by weakly nonlinear models, and study experimentally the system’s spatiotemporal dynamics, including the gene...

Non-reciprocal wave propagation in modulated elastic metamaterials.

Time-reversal symmetry for elastic wave propagation breaks down in a resonant mass-in-mass lattice whose inner-stiffness is weakly modulated in space and in time in a wave-like fashion. Specifically, one-way wave transmission, conversion and amplification as well as unidirectional wave blocking are demonstrated analytically through an asymptotic analysis based on coupled mode theory and numeric...