The absorption of visible light by metal colloids provides beautiful colored glass for aesthetic as well as practical purposes. Since the metal particles dispersed in the colloid have diameters much smaller than the wavelength of light, on the order of 10nm, the elastic scattering cross section is negligible. In typical colloidal solutions the metal particles are approximately spherical and therefore the optical constants are isotropic. Some metal/glass nanocomposites such as RG6 Schott glass contain nonspherical metal particles but the orientation of the particles in the host is random. In order to obtain a polarizing nanocomposite, the nonspherical metal particles must be aligned along a common axis. A fabrication technique based on ultrathin metal deposition has been found to provides the necessary size, shape, and orientation of the metal particles for highly anisotropic optical constants in the visible and near-IR. The measured absorption spectra of the films are analyzed by Maxwell-Garnett theory. The nanocomposite films have extinction coefficients that vary by 2 orders of magnitude depending on the polarization of the incident light. These metal nanocomposite films are useful for micro-optic and waveguide polarizers.
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