Log-pile photonic crystal fabricated by two-photon photopolymerization

The design, fabrication and evaluation of photonic crystals (PhCs) based on two-photon polymerization have been performed. In order to fabricate high quality three-dimensional (3D) log-pile PhCs with good performance in the IR region, a new resin, S-3, which has higher absorption and better optical properties for a 3D stack than commercial SCR500, is used. Several important parameters including laser intensity and overlap ratio for two-photon fabrication have been optimized. With a homemade femtosecond laser microfabrication system, two PhCs with lattice periods of 1.5 and 2 mu m are fabricated. Their photonic bandgaps (PBGs) are measured around 3.4 mu m. A simulation result of the PBG using a plane wave based on the transfer-matrix method is given, which agrees well with the observed PBG.