Fano resonances in plasmonic core-shell particles and the purcell effect

Despite a long history, light scattering by particles with size comparable with the light wavelength still unveils surprising optical phenomena, and many of them are related to the Fano effect. Originally described in the context of atomic physics, the Fano resonance in light scattering arises from the interference between a narrow subradiant mode and a spectrally broad radiation line. Here, we present an overview of Fano resonances in coated spherical scatterers within the framework of the Lorenz-Mie theory. We briefly introduce the concept of conventional and unconventional Fano resonances in light scattering. These resonances are associated with the interference between electromagnetic modes excited in the particle with different or the same multipole moment, respectively. In addition, we investigate the modification of the spontaneous-emission rate of an optical emitter at the presence of a plasmonic nanoshell. This modification of decay rate due to electromagnetic T. J. Arruda Instituto de Fı́sica de São Carlos (IFSC), Universidade de São Paulo (USP), 13566-590 São Carlos, São Paulo, Brazil, e-mail: tiagojarruda@gmail.com A. S. Martinez Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP), Universidade de São Paulo (USP), 14040-901 Ribeirão Preto, São Paulo, Brazil, e-mail: asmartinez@usp.br F. A. Pinheiro Instituto de Fı́sica, Universidade Federal do Rio de Janeiro (UFRJ), 21941-972 Rio de Janeiro, Rio de Janeiro, Brazil, e-mail: fpinheiro@if.ufrj.br R. Bachelard Departamento de Fı́sica, Universidade Federal de São Carlos (UFSCar), 13565-905 São Carlos, São Paulo, Brazil, e-mail: bachelard.romain@gmail.com S. Slama Physikalisches Institut, Eberhardt-Karls-Universität Tübingen, D-72076 Tübingen, Germany, email: sebastian.slama@uni-tuebingen.de Ph. W. Courteille Instituto de Fı́sica de São Carlos (IFSC), Universidade de São Paulo (USP), 13566-590 São Carlos, São Paulo, Brazil, e-mail: philippe.courteille@ifsc.usp.br