A process for forming a polymer template includes exposing a photoresist having polymer molecules to a light pattern and baking the photoresist to chemically react polymer molecules in portions of the photoresist that were exposed to light of the light pattern. The reacted polymer molecules have a different solubility in a solvent than chemically unreacted polymer molecules. The process also includes washing the baked photoresist with the solvent to produce a porous structure by selectively solvating one of the reacted polymer molecules and the unreacted polymer molecules. The porous structure can be used as template for forming porous structures of high refractive index materials.