トポロジカルソリトンによるチップスケール周波数コム光源（Topological Solitons Power a Chip-Scale Frequency Comb Source）

2026-03-25 カリフォルニア工科大学（Caltech）

A DOPO chip is pictured (center) integrated with a diode laser for topological soliton comb generation.Credit: Alireza Marandi

＜関連情報＞

• https://www.caltech.edu/about/news/topological-solitons-power-a-chip-scale-frequency-comb-source
• https://www.nature.com/articles/s41586-026-10292-2

ナノフォトニックニオブ酸リチウムにおけるトポロジカルソリトン周波数コム Topological soliton frequency comb in nanophotonic lithium niobate

Nicolas Englebert,Robert M. Gray,Luis Ledezma,Ryoto Sekine,Thomas Zacharias,Rithvik Ramesh,Benjamin K. Gutierrez,Pedro Parra-Rivas & Alireza Marandi
Nature  Published:25 March 2026
DOI:https://doi.org/10.1038/s41586-026-10292-2

Abstract

Frequency combs have revolutionized metrology, ranging and optical clocks¹, motivating substantial efforts on the development of chip-scale comb sources^2,3. Some on-chip comb sources exist and have been implemented through electro-optic modulation^4,5, mode-locked lasers^6,7, quantum cascade lasers^8,9,10 or soliton formation by Kerr nonlinearity^11,12. However, widespread deployment of on-chip comb sources has remained elusive, as they still require radiofrequency sources, high-Q (high-quality factor) resonators or complex stabilization schemes while facing efficiency challenges. Here, we demonstrate an on-chip frequency comb source based on the integration of a lithium niobate nanophotonic circuit with a semiconductor laser that can alleviate these challenges. We show the formation of temporal topological solitons in an on-chip nanophotonic parametric oscillator with quadratic nonlinearity and low finesse. These solitons, independent of the dispersion regime, consist of phase defects separating two π-out-of-phase continuous wave solutions at the signal frequency, which is half the input pump frequency^13,14. We use on-chip cross-correlation for temporal measurements and confirm formation of topological solitons as short as 60 fs around 2 μm, in agreement with a generalized parametrically forced Ginzburg–Landau theory^15,16,17. Moreover, we demonstrate a proof-of-concept turn-key operation of a hybrid-integrated source of topological frequency comb. Topological solitons are potential candidates for the development of integrated comb sources, which are dispersion-sign agnostic and do not require high-Q resonators or high-speed modulators, and can provide access to hard-to-reach spectral regions, including mid-infrared regions¹⁸.