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arXiv · 2507.19358

Nonlinear Terahertz Polaritonics in a Quantum Paraelectric

Chao Shen·Carla Verdi·Serafim Babkin·Maksym Serbyn·Zhanybek Alpichshev
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Abstract

Terahertz (THz) frequency range holds immense potential for high-speed data processing and signal manipulation. However, a fundamental challenge remains: the efficient and tunable control of THz electromagnetic fields. One promising approach is polaritonic engineering, which leverages hybrid light-matter excitations to manipulate THz fields at sub-wavelength scales. Here, we introduce quantum paraelectric materials as a powerful new platform for THz phonon-polaritonics, leveraging the pronounced nonlinearities of incipient ferroelectrics. These nonlinearities enable strong self- and cross-coupling between polaritons, facilitating all-optical, reconfigurable THz signal control. Using a novel space- and time-resolved imaging technique, we directly observe the ballistic propagation of bulk phonon-polaritons in SrTiO$_3$, and uncover soliton-like, dispersion-free transport in its low-temperature, quantum-fluctuation-dominated phase. Our results establish quantum paraelectric solids as a versatile and highly tunable medium for next-generation THz photonics and ultrafast information processing.

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Chao Shen, Carla Verdi, Serafim Babkin, Maksym Serbyn, Zhanybek Alpichshev. 2025-07-25. Nonlinear Terahertz Polaritonics in a Quantum Paraelectric. https://arxiv.org/abs/2507.19358

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