Colloidal photonic crystal microchannel array with periodically modulated thickness

Here we report on the optical properties of a micrometer scale array of periodically modulated thickness colloidal crystals. A combination of soft-lithography, micromolding, and microfluidics techniques is employed to form rectangular microchannels that can impose a periodic modulation of the thickness of colloidal crystals grown within them. Correspondingly, a periodic fluctuation of the photonic band structure occurs at distances of the order of a few microns. Experimental evidence of this effect is obtained by optical microspectroscopy. Results are analyzed in terms of finite crystal size theoretical calculations.