Electrostatic self-assembly processes for multilayer optical filters

Multilayer dielectric stack filters have been fabricated using the electrostatic self-assembly (ESA) process to produce quarter wavelength thicknesses of material with alternating high and low indices. The ESA technique provides significant advantages over other thin-film fabrication methods, including excellent homogeneity for low scattering loss, high thermal and chemical stability, simplicity of fabrication, and low cost. Selection of the molecules in each layer, their orientation at the molecular level, and the order of the layers allow control of bulk optical, electronic, thermal, mechanical and other properties on the nanometer scale. The resulting ability to precisely grade dielectric constant/refractive index through the film thickness makes ESA processing an excellent choice to synthesize multilayer thin-film filters and coatings, including antireflection coatings and reflecting dielectric stacks with spectral width controlled by refractive index and thickness.