Yu Yun-Jie, Kuai Yan, Fan Yong-Tao, Zhu Liang-Fu, Kong Fan-Fang, Tian Xiao-Jun, Jing Shi-Hao, Zhang Li, Zhang Dou-Guo, Zhang Yao, Zhang Yang, Dong Zhen-Chao
Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China.
Rev Sci Instrum. 2023 Jun 1;94(6). doi: 10.1063/5.0147401.
We report the design and realization of the back focal plane (BFP) imaging for the light emission from a tunnel junction in a low-temperature ultrahigh-vacuum (UHV) scanning tunneling microscope (STM). To achieve the BFP imaging in a UHV environment, a compact "all-in-one" sample holder is designed and fabricated, which allows us to integrate the sample substrate with the photon collection units that include a hemisphere solid immersion lens and an aspherical collecting lens. Such a specially designed holder enables the characterization of light emission both within and beyond the critical angle and also facilitates the optical alignment inside a UHV chamber. To test the performance of the BFP imaging system, we first measure the photoluminescence from dye-doped polystyrene beads on a thin Ag film. A double-ring pattern is observed in the BFP image, arising from two kinds of emission channels: strong surface plasmon coupled emissions around the surface plasmon resonance angle and weak transmitted fluorescence maximized at the critical angle, respectively. Such an observation also helps to determine the emission angle for each image pixel in the BFP image and, more importantly, proves the feasibility of our BFP imaging system. Furthermore, as a proof-of-principle experiment, electrically driven plasmon emissions are used to demonstrate the capability of the constructed BFP imaging system for STM induced electroluminescence measurements. A single-ring pattern is obtained in the BFP image, which reveals the generation and detection of the leakage radiation from the surface plasmon propagating on the Ag surface. Further analyses of the BFP image provide valuable information on the emission angle of the leakage radiation, the orientation of the radiating dipole, and the plasmon wavevector. The UHV-BFP imaging technique demonstrated here opens new routes for future studies on the angular distributed emission and dipole orientation of individual quantum emitters in UHV.
我们报告了在低温超高真空（UHV）扫描隧道显微镜（STM）中，用于隧道结发光的背焦平面（BFP）成像的设计与实现。为了在超高真空环境中实现BFP成像，设计并制造了一个紧凑的“一体化”样品架，它使我们能够将样品基板与光子收集单元集成在一起，光子收集单元包括一个半球形固体浸没透镜和一个非球面收集透镜。这种特殊设计的样品架能够表征临界角内外的发光情况，也便于在超高真空腔内进行光学对准。为了测试BFP成像系统的性能，我们首先测量了薄银膜上掺杂染料的聚苯乙烯珠的光致发光。在BFP图像中观察到一个双环图案，它由两种发射通道产生：分别是表面等离子体共振角附近的强表面等离子体耦合发射和临界角处最大化的弱透射荧光。这样的观察也有助于确定BFP图像中每个图像像素的发射角，更重要的是，证明了我们的BFP成像系统的可行性。此外，作为原理验证实验，电驱动等离子体发射被用于证明所构建的BFP成像系统用于STM诱导电致发光测量的能力。在BFP图像中获得了一个单环图案，它揭示了在银表面传播的表面等离子体泄漏辐射的产生和检测。对BFP图像的进一步分析提供了关于泄漏辐射发射角、辐射偶极子取向和等离子体波矢的有价值信息。这里展示的超高真空 - BFP成像技术为未来在超高真空环境中对单个量子发射器的角分布发射和偶极子取向的研究开辟了新途径。
