Polarization-sensitive optical phenomena in semiconducting and metallic nanowires

An analysis is presented of optical absorption and emission in semiconducting, metallic, and mixed core-shell nanowires are considered theoretically. Due to image forces caused by the difference in dielectric constants between nanowires and their environment, absorption and emission coefficients are different for light polarized parallel or perpendicular to the nanowire axis. As a result, the intensity and spectra of absorption, luminescence, luminescence excitation, and photoconductivity in nanowires or arrays of parallel nanowires are strongly polarization-sensitive. In random nanowire arrays, the effect may result in a "polarization memory" where the polarization of the luminescence is determined by the polarization of the exciting light. In light-emitting core-shell nanowire structures, the described redistribution of ac electric field may result in an enhancement of the luminescence from the nanowire cores in the frequency region corresponding to the plasmon resonances of their metallic shells.