Fabrication of Two-Dimensional Gel Photonic Crystals by Sol-Gel Method Using High Concentration of Alkoxide Solution

摘要

Two-dimensional (2D) photonic crystals (PCs) of transparent TiO_2 gel rods, with a diameter in the range of 0.5 to 2.0 #mu#m, arrayed in a triangular lattice with a lattice constant between 1.0 and 4.0 #mu#m, were successfully fabricated from a titanium tetra-isopropoxide (Ti(O~iPr)_4) ethylene glycol monomethyl ether (EGMME) solution using resist molds. The resist molds were fabricated on a Si wafer by electron-beam lithography. By casting the solution into the resist molds, we obtained TiO_2 gel PCs, which contained polyethylene glycol (55-60 mass%) used as a plasticizer, formed on gel plates with the same compostion over an area of 500 #mu#m X 500 #mu#m. This method enabled the preparation of dense, highly transparent TiO_2 gel PCs. Distinct changes in both reflected and transmitted colors were observed in the present gel PCs. Distinct changes in both reflected and transmitted colors were observed in the present gel PCs, demonstrating that they function as photonic crystals in the visible region.