†Center for Metamaterials and Integrated Plasmonics, Duke University, Durham, North Carolina 27708, United States.
‡Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708, United States.
Nano Lett. 2015 May 13;15(5):3578-84. doi: 10.1021/acs.nanolett.5b01062. Epub 2015 May 4.
Optical cavities with multiple tunable resonances have the potential to provide unique electromagnetic environments at two or more distinct wavelengths--critical for control of optical processes such as nonlinear generation, entangled photon generation, or photoluminescence (PL) enhancement. Here, we show a plasmonic nanocavity based on a nanopatch antenna design that has two tunable resonant modes in the visible spectrum separated by 350 nm and with line widths of ∼60 nm. The importance of utilizing two resonances simultaneously is demonstrated by integrating monolayer MoS2, a two-dimensional semiconductor, into the colloidally synthesized nanocavities. We observe a 2000-fold enhancement in the PL intensity of MoS2--which has intrinsically low absorption and small quantum yield--at room temperature, enabled by the combination of tailored absorption enhancement at the first harmonic and PL quantum-yield enhancement at the fundamental resonance.
具有多个可调谐共振的光学腔有可能在两个或更多不同波长下提供独特的电磁环境--这对于控制光学过程至关重要，如非线性产生、纠缠光子产生或光致发光（PL）增强。在这里，我们展示了一种基于纳米补丁天线设计的等离子体纳米腔，它在可见光光谱中有两个可调谐的共振模式，间隔 350nm，线宽约为 60nm。通过将二维半导体单层 MoS2 集成到胶体合成的纳米腔中，我们证明了同时利用两个共振的重要性。我们观察到 MoS2 的 PL 强度增强了 2000 倍--这是由于在基频下的 PL 量子产率增强与第一谐波下的吸收增强相结合，MoS2 的固有吸收率低，量子产率小，在室温下实现了这一增强。
