INVISIBILITY IN CERTAIN INTERSECTING PARTICLES AND ARRAYS OF SUCH PARTICLES IN A SOLID HOST

Theoretical results recently obtained for polarizability of intersecti ng spherical particles have been compared with those for polarizabilit y of intersecting cardioidal particles resembling the spherical shape. Calculations based on a modified Parseval Rule have been performed fo r a number of metals in a dielectric matrix in a quasistatic approxima tion. A large difference in the polarizabilities has been found in spi te of a striking similarity in their shapes. An unexpected small value for both the real and the imaginary part of the polarizability of car dioidal shaped metal particles occurs at wavelengths where simple meta l spheres absorb strongly. A Maxwell-Garnett model has been used to co mpare the optical properties of composite materials containing the car dioidal and intersecting spherical particles of interest. It has been found that a composite containing cardioid shaped particles in a diele ctric matrix can have an unusual response. Its absorption is very clos e to zero, while the refractive index is close to that of the fully de nse host. (C) 1996 American Institute of Physics.