意大利技术研究所Cristian Ciracì团队研究了等离子体半导体纳米结构中光学非线性的控制与增强。2025年5月13日出版的《光：科学与应用》杂志发表了这项成果。

光子集成电路中纳米级非线性元件的效率受到电介质非线性光学响应的物理限制的阻碍，这是一种基本的材料特性，无法进行工程设计。研究组通过实验证明，掺杂半导体中的超快光学非线性可以被设计出来，并且可以很容易地超过传统未掺杂电介质的非线性。重掺杂半导体的电子响应实际上具有流体动力学特性，引入了非局域效应以及额外的非线性源。 

该实验结果得到了基于流体动力学模型的全面计算分析的支持。特别是，通过研究由重n掺杂InGaAs制成的等离子体纳米天线阵列在自由载流子密度不断增加的情况下产生的三次谐波，研究组区分了流体动力学和介电非线性。最重要的是，他们证明了通过调整掺杂水平可以设计出最大的非线性效率及其光谱位置。

至关重要的是，相对于经典的介电非线性，最大效率可以提高近两个数量级。研究组采用了支持集成波导的通用材料平台InGaAs/InP，该发现为未来在所有半导体光子集成电路中利用等离子体非线性铺平了道路。

附：英文原文

Title: Control and enhancement of optical nonlinearities in plasmonic semiconductor nanostructures

Author: Rossetti, Andrea, Hu, Huatian, Venanzi, Tommaso, Bousseksou, Adel, De Luca, Federico, Deckert, Thomas, Giliberti, Valeria, Pea, Marialilia, Sagnes, Isabelle, Beaudoin, Gregoire, Biagioni, Paolo, Ba, Enrico, Maier, Stefan A., Tittl, Andreas, Brida, Daniele, Colombelli, Raffaele, Ortolani, Michele, Cirac, Cristian

Issue&Volume: 2025-05-13

Abstract: The efficiency of nanoscale nonlinear elements in photonic integrated circuits is hindered by the physical limits to the nonlinear optical response of dielectrics, which cannot be engineered as it is a fundamental material property. Here, we experimentally demonstrate that ultrafast optical nonlinearities in doped semiconductors can be engineered and can easily exceed those of conventional undoped dielectrics. The electron response of heavily doped semiconductors acquires in fact a hydrodynamic character that introduces nonlocal effects as well as additional nonlinear sources. Our experimental findings are supported by a comprehensive computational analysis based on the hydrodynamic model. In particular, by studying third-harmonic generation from plasmonic nanoantenna arrays made out of heavily n-doped InGaAs with increasing levels of free-carrier density, we discriminate between hydrodynamic and dielectric nonlinearities. Most importantly, we demonstrate that the maximum nonlinear efficiency as well as its spectral location can be engineered by tuning the doping level. Crucially, the maximum efficiency can be increased by almost two orders of magnitude with respect to the classical dielectric nonlinearity. Having employed the common material platform InGaAs/InP that supports integrated waveguides, our findings pave the way for future exploitation of plasmonic nonlinearities in all-semiconductor photonic integrated circuits.

DOI: 10.1038/s41377-025-01783-4

Source: https://www.nature.com/articles/s41377-025-01783-4