Graded-index colloidal photonic crystals and their versatile photonic applications

A novel photonic crystal in which the refractive index of the interstitial void region in a colloidal crystal is gradually changed with respect to the specific direction of the crystal was proposed. This was achieved by infiltrating polymers using the interfacial-gel polymerization with high refractive index dopants. Therefore, the resulting colloidal photonic crystal has a gradually varying stop-band at different positions of the crystal when the incident light was normal to the [111] crystallographic axis. This structure could be a kind of tunable photonic crystals based on the positional variations. The optical properties and potentials for other photonic applications will be investigated.