紧凑、开放且可调谐的二维法布里-珀罗腔

中文摘要 AI 辅助

为了增强光与物质的相互作用，可以将半导体等光学活性材料嵌入光学腔中。对于达到强耦合 regime 所需的小腔模体积，通常通过制造微腔来实现。虽然微腔能保证机械稳定性，但这些系统缺乏可调谐性，并且难以应用于范德华异质结构（vdW）等小样品。在此，我们提出一种完全可调谐的二维（2D）法布里-珀罗（FP）腔设计，该腔可容纳任何材料。该腔可自由定位在两个共焦的高数值孔径非球面透镜之间，从而支持实空间和动量空间的光学透射显微镜和光谱学。为了保持最大的机械稳定性，腔镜固定在一个整体式钛框架中。预加载的柔性铰链允许手动粗调腔长和镜面平行度，而三个压电致动器以三脚架布局可用于精细调谐。我们发现腔长波动小于100 pm，测得精细度为360，并在最小物理镜面间距380 nm处达到最低可及的 $m=3$ 腔模（空气间隙内有一个电场波腹）。为了展示腔模的二维特性，我们进行了透射模式下的动量空间成像以及光谱学测量以确定腔的色散。

英文摘要

In order to enhance light-matter interactions, optically active material, like a semiconductor, can be embedded into an optical cavity. For small cavity mode volumes, which are required for reaching the strong coupling regime, this is typically done by fabrication of microcavities. While guaranteeing a mechanically stable cavity, these systems lack tunability and are difficult to implement for small samples like van der Waals heterostructures (vdW). Here we present a design for a fully tunable two-dimensional (2D) Fabry-Pérot (FP) cavity which can host any material. The cavity can be freely positioned between two confocal high-NA aspheric lenses which allows for optical transmission microscopy and spectroscopy in real and momentum space. In order to maintain maximal mechanical stability, the cavity mirrors are held in a monolithic titanium frame. A pre-loaded flexure joint allows for manual coarse tuning of the cavity length and mirror parallelism, while three piezo actuators in a tripod layout can be used for fine tuning. We find cavity length fluctuations smaller than 100 pm, measure a finesse of 360 and reach the lowest accessible $m=3$ cavity mode (one electric field antinode within the air gap) at a minimal physical mirror separation of 380 nm. In order to demonstrate the 2D nature of the cavity mode we perform momentum space imaging in transmission as well as spectroscopy to measure the cavity dispersion.

发表机构

• Zurich University of Applied Sciences (ZHAW)（苏黎世应用科学大学）
• University of Bonn（波恩大学）
• ETH Zürich（苏黎世联邦理工学院）

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