Topologically steerable ultra-flat electro-optic combs via non-Hermitian frequency lattices
Abstract
Electro-optic (EO) frequency combs convert microwave signals to the optical domain with deterministic repetition rates, enabling applications in optical telecommunications, microwave photonics, and LiDAR. However, generating flat EO combs has remained a long-standing challenge due to exponential decay of the spectral envelope inherent to bidirectional frequency coupling within conventional schemes. Here we reveal the inherent correspondence between flat-comb generation and the topological energy bands of non-Hermitian nonreciprocal frequency lattices, and experimentally realize ultra-flat combs with topologically controlled spectral flow. We derive the exact analytical condition for flat-comb generation, and find that it maps precisely onto the complex energy band, thereby establishing a direct connection between comb-envelope engineering and non-Hermitian topology. Experimentally, we observe an ultra-flat comb whose frequency evolution direction is governed by the topological winding and remains robust against detuning and phase fluctuations. This scheme can be further extended to long-range coupling and multi-lattice architectures, underscoring its versatility for flat dual- and multi-comb generation. Our work establishes a topologically steerable approach for achieving ultra-flat EO combs, paving the way for chip-scale spectral engineering via non-Hermitian topology.
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BibTeX
@misc{liu2026topologically,
title = {{Topologically steerable ultra-flat electro-optic combs via non-Hermitian frequency lattices}},
author = {Weiwei Liu and Xiaolong Su and Bing Wang and Yongjie Wang and Pang Fu and Wenxian Zhang and Ruiqian Cheng and Songpan Hong and Qingbin Zhang and Peixiang Lu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.12867},
eprint = {2610.12867},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.12867},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Topologically steerable ultra-flat electro-optic combs via non-Hermitian frequency lattices
AU - Weiwei Liu
AU - Xiaolong Su
AU - Bing Wang
AU - Yongjie Wang
AU - Pang Fu
AU - Wenxian Zhang
AU - Ruiqian Cheng
AU - Songpan Hong
AU - Qingbin Zhang
AU - Peixiang Lu
PY - 2026
DA - 2026/10/09
PB - arXiv
DO - 10.48550/arxiv.2610.12867
UR - https://arxiv.org/abs/2610.12867
AB - Electro-optic (EO) frequency combs convert microwave signals to the optical domain with deterministic repetition rates, enabling applications in optical telecommunications, microwave photonics, and LiDAR. However, generating flat EO combs has remained a long-standing challenge due to exponential decay of the spectral envelope inherent to bidirectional frequency coupling within conventional schemes. Here we reveal the inherent correspondence between flat-comb generation and the topological energy bands of non-Hermitian nonreciprocal frequency lattices, and experimentally realize ultra-flat combs with topologically controlled spectral flow. We derive the exact analytical condition for flat-comb generation, and find that it maps precisely onto the complex energy band, thereby establishing a direct connection between comb-envelope engineering and non-Hermitian topology. Experimentally, we observe an ultra-flat comb whose frequency evolution direction is governed by the topological winding and remains robust against detuning and phase fluctuations. This scheme can be further extended to long-range coupling and multi-lattice architectures, underscoring its versatility for flat dual- and multi-comb generation. Our work establishes a topologically steerable approach for achieving ultra-flat EO combs, paving the way for chip-scale spectral engineering via non-Hermitian topology.
ER -