Cascaded photoenhancement from coupled nanoparticle and microcavity resonance effects.

Calculations, based on modal analysis of scattering and absorption by compound spheres indicate that the absorption cross sections of metal nanoparticles immobilized onto dielectric microspheres can be greatly enhanced by cavity resonances in the microspheres without significant degradation of the resonators. Gain factors for optical processes associated with the nanoparticles of 10(3) 10(4) are predicted for realistic experimental conditions using homogenous microspheres. This mechanism for cascaded photoenhancement thus has the potential of dramatically increasing the sensitivities of vibrational and photoluminescent spectroscopies.