Control of semiconductor quantum dot emission intensity and polarization by metal nanoantennas

We have studied the amplified emission properties of nanoislands with CdSe quantum dots in ZnSe/CdSe/ZnSe heterostructures surrounded by metallic antennas. It has been found that variations of the optical antenna length give rise to periodic amplification of the integral emission intensity. The period of the discovered oscillations corresponds to the wavelength of the surface plasmon-polariton mode propagating in the metallic antenna. The nature of observed periodicity was confirmed by results of numerical simulations for linear antennas. It has been established that the velocity of surface polaritons depends not only on the parameters of the dielectric constants of the metal and of the semiconductor substrate but also on the width of the metallic antenna. The influence of antenna antisymmetry (its helicity) on selective amplification of the degree of circular polarization of photoexcitation has been investigated. We found that plasmon-polariton standing waves induced in S-type (curved) antennas by circularly polarized light, which was used for quantum dot photoexcitation, result in enhanced polarization selectivity of the quantum dot emission. The selectivity of the polarization of photoexcitation is a periodic function of the helical antenna length.