Engineering stop gaps of inorganic-organic polymeric 3D woodpile photonic crystals with post-thermal treatment.

A method is reported for improving the spatial resolution and engineering the stop gaps of the inorganic-organic 3D woodpile photonic crystals (PhCs). The approach is based on the two-photon polymerization (2PP) of an inorganic-organic hybrid material and a post-thermal treatment (PTT) process. The effects of PTT on polymerized 1D, 2D and 3D structures have been characterized. Ultimately, the feature size of the suspended rods has been reduced to approximately 33 nm and the spatial resolution of inorganic-organic 3D woodpile PhCs has been improved from approximately 150 nm to approximately 86 nm. The approach is also demonstrated as a powerful tool to engineer the stop gaps of 3D PhCs. In particular, a combination of PTT and the threshold fabrication technique leads to the stop gap of a 3D woodpile PhC that can be tuned over a large wavelength range of approximately 318 nm from the near-infrared to visible region.