Two- and three-dimensional photonic crystals made of macroporous silicon and liquid crystals

Variations of the refractive index can be utilized in order to shift the stop band in periodic structures, such as photonic crystals. We report on investigations about three-dimensional macroporous silicon structures that are filled with a liquid crystal. Fourier transform infrared measurements indicate that a shift of the photonic band edge can be induced by changing the temperature. The director field in macropores within the silicon structure is investigated by ${}^{\mathrm{2}}\mathrm{H-NMR}$ spectroscopy and compared to director field simulations. The latter method indicates a preferred parallel orientation of the director in the nematic state. Based on this finding, we analyze the optical properties.