
2: POLY( p-XYLYLENE)S 51
2.5.1.2 Waveguide Coatings
Waveguides are designed to confine and direct the
propagation of light waves. Significant gains in per-
formance can be achieved when highly reflective
materials are used in combination with optically trans-
missive materials.
Silver has a reflectance of about 98% over the entire
visible light spectrum at normal incidence. In com-
parison, aluminum, a more commonly used reflective
layer material, possesses a reflectance of about 93%
at normal incidence. Therefore, silver is superior as
a reflective material in such devices. Although silver
possesses excellent optical characteristics, there are
several problems ...