Second-Order Nonlinear Microresonators on Thin-Film Lithium Tantalate
Abstract
Nonlinear frequency conversion enables coherent light generation in spectral regions that conventional lasers cannot reach directly and is foundational to the generation of squeezed states and correlated photon pairs. Implementing these nonlinear processes in microresonators lowers the required optical power by orders of magnitude but requires two conditions to be met simultaneously across wide optical bandwidths: phase matching between the interacting fields, and an appropriate coupling condition to the resonator both in the fundamental and second harmonic band. While the former can be addressed by quasi-phase matching through periodic poling, coupling two widely separated spectral bands to the resonator is nontrivial because of the wavelength dependence of mode overlap. Here, we demonstrate parametric oscillation and efficient second-harmonic generation in periodically poled racetracks on thin-film lithium tantalate on insulator. The proposed resonators feature bus-ring coupling engineered independently in the two spectral bands via a long synchronous directional coupler. Quasi-phase matching is achieved using sidewall poling that is also wavelength-calibrated and locally adapted to compensate for thickness nonuniformities. Together, these two design elements enable second-order parametric oscillation with an on-chip threshold of 181 uW and 9.8% conversion efficiency, with signal and idler tunable over tens of nanometers by a few hundred megahertz of pump detuning. Our design strategy can be flexibly applied to efficient second-harmonic generation, reaching 25% absolute conversion efficiency at milliwatt pump powers. These results show how the coupling condition is a design variable in second-order nonlinear resonators and establish thin-film lithium tantalate as a competitive platform for efficient and low-power frequency conversion.
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BibTeX
@misc{cordaro2026secondorder,
title = {{Second-Order Nonlinear Microresonators on Thin-Film Lithium Tantalate}},
author = {Andrea Cordaro and Yunxiang Song and Keith Powell and Jiayu Yang and Shengyuan Lu and Donald Witt and Tong Ge and Xudong Li and Irene Occhiodori and Nicholas Achuthan and CJ Xin and Anna Shelton and Xinrui Zhu and Neil Sinclair and Marko Lončar},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.28777},
eprint = {2610.28777},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.28777},
}
RIS
TY - UNPB
TI - Second-Order Nonlinear Microresonators on Thin-Film Lithium Tantalate
AU - Andrea Cordaro
AU - Yunxiang Song
AU - Keith Powell
AU - Jiayu Yang
AU - Shengyuan Lu
AU - Donald Witt
AU - Tong Ge
AU - Xudong Li
AU - Irene Occhiodori
AU - Nicholas Achuthan
AU - CJ Xin
AU - Anna Shelton
AU - Xinrui Zhu
AU - Neil Sinclair
AU - Marko Lončar
PY - 2026
DA - 2026/10/20
PB - arXiv
DO - 10.48550/arxiv.2610.28777
UR - https://arxiv.org/abs/2610.28777
AB - Nonlinear frequency conversion enables coherent light generation in spectral regions that conventional lasers cannot reach directly and is foundational to the generation of squeezed states and correlated photon pairs. Implementing these nonlinear processes in microresonators lowers the required optical power by orders of magnitude but requires two conditions to be met simultaneously across wide optical bandwidths: phase matching between the interacting fields, and an appropriate coupling condition to the resonator both in the fundamental and second harmonic band. While the former can be addressed by quasi-phase matching through periodic poling, coupling two widely separated spectral bands to the resonator is nontrivial because of the wavelength dependence of mode overlap. Here, we demonstrate parametric oscillation and efficient second-harmonic generation in periodically poled racetracks on thin-film lithium tantalate on insulator. The proposed resonators feature bus-ring coupling engineered independently in the two spectral bands via a long synchronous directional coupler. Quasi-phase matching is achieved using sidewall poling that is also wavelength-calibrated and locally adapted to compensate for thickness nonuniformities. Together, these two design elements enable second-order parametric oscillation with an on-chip threshold of 181 uW and 9.8% conversion efficiency, with signal and idler tunable over tens of nanometers by a few hundred megahertz of pump detuning. Our design strategy can be flexibly applied to efficient second-harmonic generation, reaching 25% absolute conversion efficiency at milliwatt pump powers. These results show how the coupling condition is a design variable in second-order nonlinear resonators and establish thin-film lithium tantalate as a competitive platform for efficient and low-power frequency conversion.
ER -