Fabrication of high-quality colloidal photonic crystals with sharp band edges for ultrafast all-optical switching

Application of the pressure controlled isothermal heating verticaldeposition method to the fabrication of colloidal photonic crystalsis systematically investigated in this paper. The fabricated samplesare characterized by scanning electron microscope and transmissionspectrum. High-quality samples with large transmissions in the passbands and the sharp band edges are obtained and the optimum growthcondition is determined. For the best sample, the transmission inthe pass bands approaches 0.9 while that in the band gap reaches0.1. More importantly, the maximum differential transmission as highas 0.1/nm is achieved. In addition, it is found that the number ofstacking layers does not increase linearly with concentration of PSspheres in a solution, and a gradual saturation occurs when theconcentration of PS spheres exceeds 1.5 wt.%. The uniformity ofthe fabricated samples is examined by transmission measurements onareas with different sizes. Finally, the tolerance of the fabricatedsamples to baking was studied.