Enhanced Coupling to Slow Photon Modes in Three-Dimensional Graded Colloidal Photonic Crystals


  • G. v. F. acknowledges support through the Deutsche Forschungsgemeinschaft under FR1671/2-1. GAO and S. J. are Government of Canada Research Chairs. We are grateful to the Natural Sciences and Engineering Research Council of Canada (NSERC) for financial support of this work.


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Enhanced coupling to slow photon modes at the band-edge of graded three-dimensional, thin-film polymer colloidal photonic crystals (see Figure) is demonstrated. For the gradation, polystyrene latex is etched by exposure to air plasma, yielding a top-to-bottom filling-fraction gradient. By monitoring transmission and corresponding phase spectra upon etching, spectral blue-shifts and enhanced mode coupling are observed. Also, surface roughness is reduced, resulting in higher structural and optical quality colloidal photonic crystals.