Fabrication of three-dimensional polymer photonic crystal structures using single diffraction element interference lithography

Abstract

This letter describes an approach for recording three-dimensional (3D) periodic structures in a photosensitive polymer using a single diffraction element mask. The mask has a central opening surrounded by three diffraction gratings oriented 120° relative to one another such that the three first order diffracted beams and the nondiffracted laser beam give a 3D spatial light intensity pattern. Structures patterned in this polymer using 1.0 and 0.56 μm grating periods have hexagonal symmetry with micron- to submicron-periodicity over large substrate area. Band structure calculations of these low index contrast materials predict photonic gaps in certain high symmetry directions.