Purcell factor enhanced scattering efficiency in optical microcavities

Scattering processes in an optical microcavity are investigated for the case of silicon nanocrystals embedded in an ultra-high Q toroid microcavity. Using a novel measurement technique based on the observable mode-splitting, we demonstrate that light scattering is highly preferential: more than 99.8% of the scattered photon flux is scattered into the original doubly-degenerate cavity modes. The large capture efficiency is attributed to an increased scattering rate into the cavity mode, due to the enhancement of the optical density of states over the free space value and has the same origin as the Purcell effect in spontaneous emission. The experimentally determined Purcell factor amounts to 883

Purcell-Factor-Enhanced Scattering from Si Nanocrystals in an Optical Microcavity

Scattering processes in an optical microcavity are investigated for the case of silicon nanocrystals embedded in an ultra-high-Q toroid microcavity. Using a novel measurement technique based on the observable mode splitting, we demonstrate that light scattering is highly preferential: more than 99.8% of the photon flux is scattered into the original doubly degenerate cavity modes. The large capture efficiency is shown to result from the Purcell enhancement of the optical density of states over the free space value, an effect that is more typically associated with spontaneous emission. The experimentally determined Purcell factor has a lower bound of 171

Absorption and Scattering Microscopy of Single Metal Nanoparticles.

Several recently developed detection techniques opened studies of individual metal nanoparticles (1-100 nm in diameter) in the optical far field. Eliminating averaging over the broad size and shape distributions produced by even the best of current synthesis methods, these studies hold great promise for gaining a deeper insight into many of the properties of metal nanoparticles, notably electronic and vibrational relaxation. All methods are based on detection of a scattered wave emitted either by the particle itself, or by its close environment. Direct absorption and interference techniques rely on the particle's scattering and have similar limits in signal-to-noise ratio. The photothermal method uses a change in the refractive index of the environment as an additional step to enhance the scattered wave. This leads to a considerably improved sensitivity. We briefly discuss and compare these various techniques, review the new results they generated so far, and conclude on their great potential for nanoscience and for single-molecule labelling in biological assays and live cells