近日，加拿大渥太华大学的Jean-Michel Menard及其研究团队取得一项新进展。经过不懈努力，他们提出结合多层、栅控和基于超材料的架构增强太赫兹谐波生成的策略。相关研究成果已于2025年1月9日在国际知名学术期刊《光：科学与应用》上发表。

该研究团队展示了结合多种策略以增强基于石墨烯结构的太赫兹（THz）非线性效应的样本架构。研究人员通过多层设计增加相互作用长度、使用电栅极控制载流子密度，以及利用金属超表面基底调制THz场空间分布来实现这一目标。这项研究特别使用了台式高场THz源来探究三次谐波生成（THG）。

研究人员测得的THG增强因子超过30，并提出了能够实现两个数量级增强的架构。这些发现凸显了工程化石墨烯基结构在推动用于信号处理和无线通信应用的THz频率转换技术方面的潜力。

据悉，石墨烯具有独特的性质，为未来的突破性应用铺平了道路。其显著的光学非线性和易于集成到器件中的特点，使其成为全光开关和频率转换应用中的理想关键组件。在太赫兹（THz）波段，人们已经独立地演示了多种方法来优化石墨烯中的非线性效应，从而解决了由原子级薄相互作用长度引起的关键限制。

附：英文原文

Title: Strategies to enhance THz harmonic generation combining multilayered, gated, and metamaterial-based architectures

Author: Maleki, Ali, Heindl, Moritz B., Xin, Yongbao, Boyd, Robert W., Herink, Georg, Menard, Jean-Meichel

Issue&Volume: 2025-01-09

Abstract: Graphene has unique properties paving the way for groundbreaking future applications. Its large optical nonlinearity and ease of integration in devices notably makes it an ideal candidate to become a key component for all-optical switching and frequency conversion applications. In the terahertz (THz) region, various approaches have been independently demonstrated to optimize the nonlinear effects in graphene, addressing a critical limitation arising from the atomically thin interaction length. Here, we demonstrate sample architectures that combine strategies to enhance THz nonlinearities in graphene-based structures. We achieve this by increasing the interaction length through a multilayered design, controlling carrier density with an electrical gate, and modulating the THz field spatial distribution with a metallic metasurface substrate. Our study specifically investigates third harmonic generation (THG) using a table-top high-field THz source. We measure THG enhancement factors exceeding thirty and propose architectures capable of achieving a two-order-of-magnitude increase. These findings underscore the potential of engineered graphene-based structures in advancing THz frequency conversion technologies for signal processing and wireless communication applications.

DOI: 10.1038/s41377-024-01657-1

Source: https://www.nature.com/articles/s41377-024-01657-1