Wake-Tail Effects in Two-Dimensional Wave Refocusing

Fuente: arXiv
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Main Author: Koutserimpas, Theodoros T.
Format: Preprint
Published: 2026
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author Koutserimpas, Theodoros T.
author_facet Koutserimpas, Theodoros T.
contents In even spatial dimensions, solutions of the wave equation violate Huygens' principle, producing a persistent wake tail inside the light cone rather than a sharply localized propagating front. This intrinsic tail complicates refocusing. Here, we examine how the wake-tail structure of the two-dimensional wave equation affects refocusing, using the analytically tractable example of a pulse generated by a source localized in both space and time. Two idealized concentration strategies are considered. A spatial mirror reflects the outgoing pulse and produces refocusing, but the redirected signal is broadened, with the wake tail preserving its causal ordering behind the propagating front. A second strategy employs a time mirror generated by abrupt temporal modulation of the phase velocity, producing temporal reflection and transmission. This mechanism introduces an anti-causal response of the wake-tail, reversing its temporal ordering in a time-reversal-like manner; however, the pulse still undergoes distortion and wake-tail contributions persist through secondary radiation at the refocus point. These results demonstrate the fundamental connection between Huygens' principle and wave concentration, showing that the wake-tail structure intrinsic to two-dimensional propagation imposes a fundamental limit on perfect refocusing, even under idealized conditions.
format Preprint
id arxiv_https___arxiv_org_abs_2603_17688
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Wake-Tail Effects in Two-Dimensional Wave Refocusing
Koutserimpas, Theodoros T.
Optics
In even spatial dimensions, solutions of the wave equation violate Huygens' principle, producing a persistent wake tail inside the light cone rather than a sharply localized propagating front. This intrinsic tail complicates refocusing. Here, we examine how the wake-tail structure of the two-dimensional wave equation affects refocusing, using the analytically tractable example of a pulse generated by a source localized in both space and time. Two idealized concentration strategies are considered. A spatial mirror reflects the outgoing pulse and produces refocusing, but the redirected signal is broadened, with the wake tail preserving its causal ordering behind the propagating front. A second strategy employs a time mirror generated by abrupt temporal modulation of the phase velocity, producing temporal reflection and transmission. This mechanism introduces an anti-causal response of the wake-tail, reversing its temporal ordering in a time-reversal-like manner; however, the pulse still undergoes distortion and wake-tail contributions persist through secondary radiation at the refocus point. These results demonstrate the fundamental connection between Huygens' principle and wave concentration, showing that the wake-tail structure intrinsic to two-dimensional propagation imposes a fundamental limit on perfect refocusing, even under idealized conditions.
title Wake-Tail Effects in Two-Dimensional Wave Refocusing
topic Optics
url https://arxiv.org/abs/2603.17688