Diffraction element assisted lithography: Pattern control for photonic crystal fabrication

Near-field diffraction element assisted lithography or DEAL has been used to fabricate two-dimensional lattice patterns in a photoresist. Specifically, a diffraction element was used to prepattern the coherent output of a laser prior to its capture in a photoresist. The pattern symmetry and spacing can be readily modified with the same experimental arrangement since the near-field diffraction pattern strongly depends on the nature of the diffractive element and the distance between the element and the photoresist. The patterns that are formed can serve as masks for patterning high index materials to create photonic band gap crystals. Alternatively, they have the potential to behave as two-dimensional photonic band gap arrays provided the polymer used exhibits a large enough index contrast.