Abstract

The optical absorption of metal/insulator composites, where the diameter of the metal particles is much less than the wavelength of the incident radiation, is given by the Maxwell Garnett theory in terms of the separate dielectric functions of the metal and the insulator. Further simplification of these expressions can be obtained if the metal dielectric function can be represented by the Drude model. Once the Drude parameters E_p (plasma frequency), Γ (damping constant), and e_b (background dielectric constant) are known for a metal, the location, height, and width of the composite absorption bands can be expressed in terms of these parameters, the value of the insulator dielectric constant, and the metal volume fraction in the composite. Approximate closed-form expressions are developed for the case of good metallic conductors and are used to relate the composite absorption to the dc conductivity of the metal particles and can be interpreted in terms of standard oscillator results.

© 1989 Optical Society of America