Multicolor patterning using holographic woodpile photonic crystals at visible wavelengths.

High-quality woodpile structures with photonic band gaps in the visible wavelength range were fabricated using a single prism holographic lithography technique. Woodpile structures were prepared to have a rod diameter of 160 nm, a lateral periodicity of 240 nm, and an axial periodicity of 300 nm, which is the smallest feature size for three-dimensional nanopatterned structures. A multicolor patterning method was used to vary the degree of crosslinking in the negative photoresist. These woodpile structures showed enhanced fluorescence due to a large surface area and the presence of bicontinuous interconnected pores.