Nanodipoles for an optical phased array

Two realizations of an optical electric dipole emitter are considered in the application to a dipole optical phased Arran, project. Realization 1 is a dielectric disc in which a leaky wave of the E-0m0 type is excited. Realization 2 is a piece of nanowire of a well-reflecting metal (Ag) coated with a dielectric layer (ZnO). In the second case, a surface plasmon is excited. Excitation of the surface plasmon is shown to be also possible in the case where the permittivity of the coating exceeds the absolute value of the permittivity of the metal epsilon. The permittivity, of the surrounded medium is less than vertical bar epsilon vertical bar. There is a restriction to the thickness of the ZnO coating. Losses in the disc and coated nano,wire are calculated. In the former case, the losses are due to radiation; in the latter case, to losses in the metal and to radiation. The radiation absorption coefficients are assessed to be rather high, similar to 10(5) cm(-1).