Generalized coherent wave control at dynamic interfaces

TL;DR

This paper introduces a novel method for coherent wave control at dynamic interfaces, enabling wave manipulation across different frequencies and wavevectors by leveraging spatiotemporal engineering, which broadens the scope of wave shaping and pulse generation.

Contribution

It generalizes coherent wave control to spatiotemporally engineered media with dynamic interfaces, breaking traditional frequency constraints and allowing flexible wave manipulation.

Findings

Enables interference between waves of different frequencies and wavevectors.

Allows elimination of specific propagating waves by controlling incident phases.

Demonstrates suppression of forward waves in microstrip lines with photodiode switches.

Abstract

Coherent wave control is of key importance across a broad range of fields such as electromagnetics, photonics, and acoustics. It enables us to amplify or suppress the outgoing waves via engineering amplitudes and phases of multiple incidences. However, within a purely spatially (temporally) engineered medium, coherent wave control requires the frequency of the associated incidences to be identical (opposite). In this work, we break this conventional constraint by generalizing coherent wave control into a spatiotemporally engineered medium, i.e., the system featuring a dynamic interface. Owing to the broken translational symmetry in space and time, both the subluminal and superluminal interfaces allow interference between scattered waves regardless of their different frequencies and wavevectors. Hence, one can flexibly eliminate the backward- or forward-propagating waves scattered from the dynamic interfaces by controlling the incident amplitudes and phases. Our work not only presents a generalized way for reshaping arbitrary waveforms but also provides a promising paradigm to generate ultrafast pulses using low-frequency signals. We have also implemented suppression of forward-propagating waves in microstrip transmission lines with fast photodiode switches.