A reversibly tunable colloidal photonic crystal via the infiltrated solvent liquid–solid phase transition

A reversibly tunable colloidal photonic crystal between two stop bands was realized by a liquid–solid phase transition of liquid infiltrated into the air voids of silica opals. The difference of the peak wavelengths of the two stop bands was dependent on the diameter of the silica opals and the difference of the refractive index of the filled solvent between the solid and liquid state. The reversibly tunable photonic crystals have good stability and reproducibility.