An optical device includes a substrate, a reflecting stack and optionally,
a cap layer. The reflecting stack has a first plurality of optical thin
film layers and a second plurality of optical thin film layers. The first
plurality of optical thin film layers are carried by the substrate, and
are configured and adapted to be highly reflective of light of a first
predetermined wavelength incident upon the optical device at a first
predetermined angle. The second plurality of optical thin film layers are
carried by the substrate and are configured and adapted to be
substantially antireflective of light of a second predetermined
wavelength incident upon the optical device at a second predetermined
angle. The second plurality of layers are interposed between individual
layers of the first plurality of layers. The cap layer, if provided, is
carried by the reflecting stack.