Maleki Ali, Heindl Moritz B, Xin Yongbao, Boyd Robert W, Herink Georg, Ménard Jean-Michel
Department of Physics, University of Ottawa, Ottawa, ON, K1N 6N5, Canada.
Experimental Physics VIII - Ultrafast Dynamics, University of Bayreuth, Bayreuth, 95447, Germany.
Light Sci Appl. 2025 Jan 9;14(1):44. doi: 10.1038/s41377-024-01657-1.
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.
石墨烯具有独特的性质，为开创性的未来应用铺平了道路。其巨大的光学非线性以及在器件中易于集成的特性，使其成为全光开关和频率转换应用关键组件的理想候选材料。在太赫兹（THz）区域，人们已独立展示了各种方法来优化石墨烯中的非线性效应，解决了因原子级薄的相互作用长度而产生的关键限制。在此，我们展示了结合多种策略以增强基于石墨烯结构中太赫兹非线性的样品架构。我们通过多层设计增加相互作用长度、用电栅控制载流子密度以及用金属超表面衬底调制太赫兹场空间分布来实现这一目标。我们的研究具体使用桌面型高场太赫兹源研究了三次谐波产生（THG）。我们测量到三次谐波产生增强因子超过30，并提出了能够实现两个数量级增长的架构。这些发现突出了工程化的基于石墨烯的结构在推进用于信号处理和无线通信应用的太赫兹频率转换技术方面的潜力。
