近日，美国斯坦福大学的Mark L.Brongersma及其研究小组取得一项新进展。经过不懈努力，他们成功研制了Purcell使能的单层半导体自由空间光学调制器。相关研究成果已于2023年7月17日在国际知名学术期刊《自然—光子学》上发表。

该研究团队通过阐明一般途径，成功减少了器件电极对光子设计的不良影响。研究人员设计了一个能够显著提高Purcell增强的结构，加速了所需的辐射衰减，并实现了便利的电门控和电荷注入功能。他们利用基于原子薄层半导体的自由空间光学调制器来验证了这一概念。通过设计具有纳米图案的银栅极衬垫来调控等离激元共振响应，他们成功地将二硫化钨单层中激子的辐射衰减率提高了一个数量级，从而在室温下实现了创纪录的高调制效率。

实验结果显示，他们观察到了10%的反射率变化和3dB的信号调制，相较于在真空中使用悬浮单层的调制，增强了20倍。此外，研究人员还展示了如何通过设计表面图案来实现光场的动态控制。这项研究强调了应用辐射衰减工程作为创造高性能器件的有效工具，为提高材料质量做出了重要贡献。

据悉，失相和非辐射衰变限制了室温下各种量子器件的性能。

附：英文原文

Title: A Purcell-enabled monolayer semiconductor free-space optical modulator

Author: Li, Qitong, Song, Jung-Hwan, Xu, Fenghao, van de Groep, Jorik, Hong, Jiho, Daus, Alwin, Lee, Yan Joe, Johnson, Amalya C., Pop, Eric, Liu, Fang, Brongersma, Mark L.

Issue&Volume: 2023-07-17

Abstract: Dephasing and non-radiative decay processes limit the performance of a wide variety of quantum devices at room temperature. Here we illustrate a general pathway to notably reduce the detrimental impact of these undesired effects through photonic design of the device electrodes. Our design facilitates a large Purcell enhancement that speeds up competing, desired radiative decay while also enabling convenient electrical gating and charge injection functions. We demonstrate the concept with a free-space optical modulator based on an atomically thin semiconductor. By engineering the plasmonic response of a nanopatterned silver gate pad, we successfully enhance the radiative decay rate of excitons in a tungsten disulfide monolayer by one order of magnitude to create record-high modulation efficiencies for this class of materials at room temperature. We experimentally observe a 10% reflectance change as well as 3dB signal modulation, corresponding to a 20-fold enhancement compared with modulation using a suspended monolayer in vacuum. We also illustrate how dynamic control of light fields can be achieved with designer surface patterns. This research highlights the benefits of applying radiative decay engineering as a powerful tool in creating high-performance devices that complements substantial efforts to improve the quality of materials.

DOI: 10.1038/s41566-023-01250-9

Source: https://www.nature.com/articles/s41566-023-01250-9