Frequency Selective Wave Beaming in Nonreciprocal Acoustic Phased Arrays

TL;DR

This paper introduces a controllable space-time acoustic phased array that breaks reciprocity, allowing asymmetric transmission and reception, with potential applications in ultrasonic imaging, non-destructive testing, and underwater communication.

Contribution

It presents a novel dynamic phase modulation technique for acoustic phased arrays that enables nonreciprocal behavior and independent tuning of transmission and reception patterns.

Findings

Supports asymmetric transmission and reception patterns

Enables frequency conversion and wave direction control

Validated through numerical experiments

Abstract

Acoustic phased arrays are capable of steering and focusing a beam of sound via selective coordination of the spatial distribution of phase angles between multiple sound emitters. Constrained by the principle of reciprocity, conventional phased arrays exhibit identical transmission and reception patterns which limit the scope of their operation. This work presents a controllable space-time acoustic phased array which breaks time-reversal symmetry, and enables phononic transition in both momentum and energy spaces. By leveraging a dynamic phase modulation, the proposed linear phased array is no longer bound by the acoustic reciprocity, and supports asymmetric transmission and reception patterns that can be tuned independently at multiple channels. A foundational framework is developed to characterize and interpret the emergent nonreciprocal phenomena and is later validated against benchmark numerical experiments. The new phased array selectively alters the directional and frequency content of the incident signal and the frequency conversion between the different wave fields is analyzed as a function of the imposed modulation. The space-time acoustic phased array enables unprecedented control over sound waves in a variety of applications ranging from ultrasonic imaging to non-destructive testing and underwater SONAR telecommunication.