Optical simulation of colloidal photonic crystals with controllable size spheres of silica

In this work, optical properties of colloidal silica crystals are investigated theoretically. Numerical calculations are discussed and compared to experimental measurements. The existence of photonic band gap (or stop band) is inferred by analyzing the transmission spectra and dips of low transmission are typically correlated with photonic band gaps. The position of the main dip in simulated spectra matches the pseudo photonic band gap expected by the calculated photonic band gap diagram. Positions of stop band show a strong dependence on the diameter of silica spheres. We note that positions of the main dips deduced from simulated and measured spectra are very near. Good agreement between measured and theoretical results is then reported.