Massively Degenerate Coherent Perfect Absorption in Gradient-Index Fibers
Abstract
Coherent perfect absorbers (CPAs) have recently attracted considerable attention due to their ability to enhance light--matter interaction. By exploiting interference, CPAs enable even weakly absorbing materials to achieve complete absorption under appropriate excitation conditions. Generalizing this concept to the simultaneous absorption of arbitrary multimode input states remains challenging, however, since conventional implementations typically operate only for a single or a very small number of input channels. Here, we propose a compact realization of a multimode coherent perfect absorber based on a gradient-index (GRIN) fiber. Using the self-imaging property of the fiber, the bulky free-space architecture of previous approaches is replaced by a monolithic waveguiding platform that supports near-degenerate rephasing of many spatial modes. We show that standard GRIN profiles optimized for minimal intermodal dispersion enable highly efficient absorption of complex multimode fields, with field-of-view reflectivities well below 1% for realistic parameters. This approach provides a practical and scalable route toward efficient multimode absorption in fiber-based and integrated photonic systems, with potential applications in light harvesting, optical control, and imaging.
Versions
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BibTeX
@misc{horner2026massively,
title = {{Massively Degenerate Coherent Perfect Absorption in Gradient-Index Fibers}},
author = {Helmut Hörner and Şahin K. Özdemir and Stefan Rotter},
howpublished = {arXiv},
year = {2026},
month = may,
doi = {10.48550/arxiv.2605.15998},
eprint = {2605.15998},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.15998},
}
RIS
TY - UNPB
TI - Massively Degenerate Coherent Perfect Absorption in Gradient-Index Fibers
AU - Helmut Hörner
AU - Şahin K. Özdemir
AU - Stefan Rotter
PY - 2026
DA - 2026/05/15
PB - arXiv
DO - 10.48550/arxiv.2605.15998
UR - https://arxiv.org/abs/2605.15998
AB - Coherent perfect absorbers (CPAs) have recently attracted considerable attention due to their ability to enhance light--matter interaction. By exploiting interference, CPAs enable even weakly absorbing materials to achieve complete absorption under appropriate excitation conditions. Generalizing this concept to the simultaneous absorption of arbitrary multimode input states remains challenging, however, since conventional implementations typically operate only for a single or a very small number of input channels. Here, we propose a compact realization of a multimode coherent perfect absorber based on a gradient-index (GRIN) fiber. Using the self-imaging property of the fiber, the bulky free-space architecture of previous approaches is replaced by a monolithic waveguiding platform that supports near-degenerate rephasing of many spatial modes. We show that standard GRIN profiles optimized for minimal intermodal dispersion enable highly efficient absorption of complex multimode fields, with field-of-view reflectivities well below 1% for realistic parameters. This approach provides a practical and scalable route toward efficient multimode absorption in fiber-based and integrated photonic systems, with potential applications in light harvesting, optical control, and imaging.
ER -