Metal-covered photonic bandgap multilayer for infrared hollow waveguides

Infrared hollow waveguides utilizing a dielectric multilayer are examined by use of a photonic bandgap theory. It is shown that, in the waveguide consisting of quarter-wave film stack, the act of covering the dielectric films with a metal layer is effective in the reduction of the number of film layers. To verify the effect of this design, we fabricated a prototype waveguide with three dielectric layers of SiO₂/Ta₂O₅/SiO₂and a silver layer by using a liquid-phase coating technique. From the loss spectrum of the fabricated waveguide, it is confirmed that, as designed, the waveguide shows wideband low-loss property at the wavelength of Nd:YAG laser light 1.06 μm.