Di Francescantonio Agostino, Sabatti Alessandra, Weigand Helena, Bailly-Rioufreyt Elise, Vincenti Maria Antonietta, Carletti Luca, Kellner Jost, Zilli Attilio, Finazzi Marco, Celebrano Michele, Grange Rachel
Politecnico di Milano, Physics Department, Milano, Italy.
ETH Zürich, Department of Physics, Institute for Quantum Electronics, Optical Nanomaterial Group, Zürich, Switzerland.
Nat Commun. 2025 Jul 30;16(1):7000. doi: 10.1038/s41467-025-62072-7.
Electro-optical modulation is essential in optical signal processing and laser technology, yet modulators based on the Pockels effect in flat optics lag behind bulk and integrated platforms in efficiency and speed. We bridge this gap realizing a metasurface based on lithium niobate (LiNbO₃) on insulator that leverages on resonances with quality-factor as high as 8000 to achieve fast electrical modulation of both linear and nonlinear optical properties. LiNbO, well known for its high nonlinear susceptibility and wide transparency window across the infrared and visible spectrum, is employed to realize an asymmetric, one-dimensional array of nanowires, exhibiting resonances with linewidth <0.2 nm. The metasurface achieves a reflectivity modulation around 0.1, with a modulation efficiency, defined as relative modulation per applied Volt, larger than 0.01 V on a -3 dB (-6 dB) bandwidth of about 800 MHz (1.4 GHz). Additionally, we demonstrate more than one order of magnitude intensity modulation of the second harmonic seeded by a continuous-wave laser, with a modulation efficiency of about 0.12 V. This dual modulation capability, rooted in the interplay between optical resonances and electric field manipulation, holds significant potential for cutting-edge applications in high-speed photonics, nonlinear optics, and reconfigurable communication systems.
电光调制在光信号处理和激光技术中至关重要，然而基于平面光学中普克尔效应的调制器在效率和速度方面落后于体光学和集成平台。我们通过实现一种基于绝缘体上铌酸锂（LiNbO₃）的超表面来弥合这一差距，该超表面利用高达8000的品质因数的共振来实现线性和非线性光学特性的快速电调制。铌酸锂以其高非线性极化率和跨越红外和可见光谱的宽透明窗口而闻名，被用于实现一种不对称的一维纳米线阵列，其共振线宽<0.2nm。该超表面实现了约0.1的反射率调制，在约800MHz（1.4GHz）的 -3dB（-6dB）带宽上，定义为每施加伏特的相对调制的调制效率大于0.01V⁻¹。此外，我们展示了由连续波激光种子产生的二次谐波的强度调制超过一个数量级，调制效率约为0.12V⁻¹。这种基于光学共振和电场操纵之间相互作用的双重调制能力，在高速光子学、非线性光学和可重构通信系统的前沿应用中具有巨大潜力。
