Use of a Single Nanoparticle as Localized Light Source

Full text: In this work, we have identified different types of inorganic spherical nanoparticles that can be trapped by near-infrared (IR) laser tweezers and simultaneously used as a local near-field light source. Visible light emission is then exclusively induced by the IR trapping laser. In particular, we show that we can detect electromagnetic non-linear optical field enhancement resulting from surface plasmon excitation on a trapped gold nanosphere. Furthermore, we demonstrate optical trapping of a single KNbO3 nanoparticle along with second harmonic excitation by the IR laser. In parallel, we can quantify the forces acting on the trapped nanoparticle by measuring its 3D Brownian fluctuations with nanometer spatial and microsecond temporal resolutions through interferometric position detection. The long term goal is to use a single near-field probe for versatile and multidimensional microspectroscopy to obtain local information, such as fluorescence, dynamical and mechanical properties of molecules surrounding the particle. (author)