Photochromic switching of narrow-band lattice resonances.

Abstract

Narrow-band resonances supported by a variety of periodic metallic or dielectric nanostructures have great potential applications in light sources, optical sensors, and switches or modulators. Here we report the switching of narrow-band lattice resonances in a mirror-backed two-dimensional array of dielectric nanopillars. The nanopillar is composed of a silica core and photochromic coating. By exposure to ultraviolet light, the photochromic molecules can be turned into a state that is highly absorptive around the wavelength of the lattice resonance. Because the lattice resonance has enhanced the near-fields concentrated on the tops of dielectric nanopillars, the absorptive coating can destroy this resonance. The absorptive state of the photochromic molecules can be recovered to a transparent state by exposure to visible light. We fabricate the device and characterize the change of reflection spectra to demonstrate the reversible switching of lattice resonances by exposure to ultraviolet and visible light alternately. An all-optical control of the narrow-band photoluminescence is further demonstrated by combining a fluorescent dye with the photochromic molecules.