Optical Manipulation and Spectroscopy Of Silicon Nanoparticles Exhibiting Dielectric Resonances.

We demonstrate that silicon (Si) nanoparticles with scattering properties exhibiting strong dielectric resonances can be successfully manipulated using optical tweezers. The large dielectric constant of Si has a distinct advantage over conventional colloidal nanoparticles in that it leads to enhanced trapping forces without the heating associated with metallic nanoparticles. Further, the spectral features of the trapped nanoparticles provide a unique marker for probing size, shape, orientation and local dielectric environment. We exploit these properties to investigate the trapping dynamics of Si nanoparticles with different dimensions ranging from 50 to 200 nm and aspect ratios between 0.4 and 2. The unique combination of spectral and trapping properties make Si nanoparticles an ideal system for delivering directed nanoscale sensing in a range of potential applications.