Two-photon fabrication of photonic crystals by single-beam laser holographic lithography
We demonstrate a novel approach for the easy fabrication of photonic crystals (PCs) with arbitrary optical lattice using two-photon holographic lithography (HL). The quadratic dependence of the two-photon absorption process dramatically increases the contrast of the pattern and the low absorption coefficient of the photoresist at 720 nm lead to a high aspect ratio and low fluctuation of the pattern. By applying such a technique, defect-free and highly uniform one-dimensional gratings, two-dimensional quasicrystals, and three-dimensional (3D) face center cube-type PCs of high aspect ratio and small filling factor are obtained. This two-photon based HL technique is particularly suitable for making 3D PCs and quasicrystals with complex and fine structural details.