Study of optical absorption and dispersion in a semiconductor - metal nanoparticle hybrid system: Exciton-plasmon coupling

In this paper, optical properties of a hybrid system consisting of a semiconductor quantum dot placed in the vicinity of a metal (plasmonic) nanoparticle with spherical and ellipsoidal symmetry is investigated. An analytical expression for the absorption and dispersion using the density-matrix approach via semi-classical theory is derived and numerically discussed. In our numerical calculations, we have used Au and Ag metals, because these metals have predominately been the materials of choice for plasmonic applications around the optical frequencies. It is shown that the optical dispersion and absorption strongly depends on the particle size and shape, the quantum dot-nanoparticle distance (the semiconductor quantum dot-plasmonic nanoparticle center-to-center distance), and the dielectric constant of host matrix. It is important to note that dependences of optical properties of a hybrid system on changing and adjusting of the geometrical parameters of system can be used for optical sensing purposes and design of tunable bio-nanosensors.