Optical property of photonic crystals infiltrated with various liquids and liquid crystals

Upon infiltration of various liquids in opal and its polymer replica photonic crystals with a three-dimensional periodic structure of the order of the optical wavelength, the color changed remarkably and the sharp reflection peak and absorption dip changed drastically with wavelength. These shifts are strongly dependent on the sort of infiltrated liquids and can be explained by the difference of refractive index of the liquid. On the contrary from these spectral shifts, the refractive index of the infiltrated liquid is easily evaluated. Utilizing these spectral shifts, the refractive index of the liquid and in the case of mixed liquid, the concentration of each component of liquid can be evaluated. Theoretical calculations supported this interpretation. Photonic crystals infiltrated with liquid crystals and the effects of applied field are also studied and the mechanism of the novel optical property has been clarified.