NanoPhotonics Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, UK.
Department of Electrical Engineering (ESAT-TELEMIC), KU Leuven, Leuven, Belgium.
Science. 2021 Dec 3;374(6572):1268-1271. doi: 10.1126/science.abk2593. Epub 2021 Dec 2.
Coherent interconversion of signals between optical and mechanical domains is enabled by optomechanical interactions. Extreme light-matter coupling produced by confining light to nanoscale mode volumes can then access single mid-infrared (MIR) photon sensitivity. Here, we used the infrared absorption and Raman activity of molecular vibrations in plasmonic nanocavities to demonstrate frequency upconversion. We converted approximately 10-micrometer-wavelength incoming light to visible light by surface-enhanced Raman scattering (SERS) in doubly resonant antennas that enhanced upconversion by more than 10. We showed 140% amplification of the SERS anti-Stokes emission when an MIR pump was tuned to a molecular vibrational frequency, obtaining lowest detectable powers of 1 to 10 microwatts per square micrometer at room temperature. These results have potential for low-cost and large-scale infrared detectors and spectroscopic techniques.
通过光机械相互作用，可以实现光学和机械域之间的信号相干转换。通过将光限制在纳米级模体积中产生的极端光物质耦合，可以实现单个中红外（MIR）光子的灵敏度。在这里，我们使用等离子体纳米腔中的分子振动的红外吸收和拉曼活性来演示频率上转换。我们通过双重共振天线中的表面增强拉曼散射（SERS）将大约 10 微米波长的入射光转换为可见光，该天线将上转换增强了 10 倍以上。当 MIR 泵调谐到分子振动频率时，我们观察到 SERS 反斯托克斯发射的 140%放大，从而在室温下获得了每平方微米 1 至 10 微瓦的最低可检测功率。这些结果对于低成本和大规模的红外探测器和光谱技术具有潜在的应用前景。
