Frequency selective wave beaming in nonreciprocal acoustic phased arrays

Revant Adlakha,Mohammad A Attarzadeh,Amjad Aref,Mostafa Nouh,Mohammadreza Moghaddaszadeh

doi:10.1038/s41598-020-77489-x

Revant Adlakha, Mohammad A Attarzadeh + Show 3 more

Open Access

https://doi.org/10.1038/s41598-020-77489-x

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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 imparts a frequency conversion between different wave fields, which is further 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.

Highlights

While we present in-line acoustic phased arrays as a proof of concept, the physical insights demonstrated here readily extend to higher dimensions which are fairly application-oriented
We report on the transient performance of the STP phased array by using a semi-analytical in-house algorithm that does not incorporate far-field approximations
The operational principle of the phased array was developed through theoretical derivation and a Jacobi–Anger series expansion

Summary

Introduction

We observe that the STP phased array exhibits three independent principal TX channels, each operating at a different frequency (namely ω , ω(1+) and ω(1−)) and is capable of transmitting waves in different non-trivial directions. The framework shown here depicts a non-trivial and unprecedented level of control over both the direction and frequency (channel) of the transmitted wave beams in the STP array, which solely emerges as a consequence of the imposed space–time modulation.

Results

Conclusion