Boundary singular scattering enables coherent perfect absorption and lasing without resonators
Abstract
Scattering singularities are features conventionally associated with resonant scattering bodies, which correspond to the zeros and poles of a scattering matrix, and manifest as coherent perfect absorption and lasing respectively. Here, we show that they can emerge solely from an interface, eliminating the need for any resonant body. We introduce boundary singular scattering, whereby an interface between two non-Hermitian media supports coherent perfect absorption, lasing, or both. Despite these singular responses, the two adjoining media are in parity-time (PT)-unbroken phases, with entirely real bulk spectra. This phenomenon originates from a singular boundary mode-matching condition unique to non-Hermitian systems, not from any underlying resonant modes. We demonstrate it experimentally in a programmable synthetic photonic lattice, and show coherent switching between perfect absorption and lasing by controlling only the relative phase of the incident beams. The same mechanism further generalizes from mirror-symmetric interfaces to asymmetric interfaces with dissimilar bulk dispersions. Our work establishes boundaries as a previously unexplored origin of scattering singularities, opening a resonator-free route to coherent perfect absorption, lasing, and other singular wave phenomena.
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BibTeX
@misc{yu2026boundary,
title = {{Boundary singular scattering enables coherent perfect absorption and lasing without resonators}},
author = {Letian Yu and Xu Zheng and Cesare Soci and Y. D. Chong and Baile Zhang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.27429},
eprint = {2609.27429},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.27429},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Boundary singular scattering enables coherent perfect absorption and lasing without resonators
AU - Letian Yu
AU - Xu Zheng
AU - Cesare Soci
AU - Y. D. Chong
AU - Baile Zhang
PY - 2026
DA - 2026/09/23
PB - arXiv
DO - 10.48550/arxiv.2609.27429
UR - https://arxiv.org/abs/2609.27429
AB - Scattering singularities are features conventionally associated with resonant scattering bodies, which correspond to the zeros and poles of a scattering matrix, and manifest as coherent perfect absorption and lasing respectively. Here, we show that they can emerge solely from an interface, eliminating the need for any resonant body. We introduce boundary singular scattering, whereby an interface between two non-Hermitian media supports coherent perfect absorption, lasing, or both. Despite these singular responses, the two adjoining media are in parity-time (PT)-unbroken phases, with entirely real bulk spectra. This phenomenon originates from a singular boundary mode-matching condition unique to non-Hermitian systems, not from any underlying resonant modes. We demonstrate it experimentally in a programmable synthetic photonic lattice, and show coherent switching between perfect absorption and lasing by controlling only the relative phase of the incident beams. The same mechanism further generalizes from mirror-symmetric interfaces to asymmetric interfaces with dissimilar bulk dispersions. Our work establishes boundaries as a previously unexplored origin of scattering singularities, opening a resonator-free route to coherent perfect absorption, lasing, and other singular wave phenomena.
ER -