title: Two-dimensional subwavelength gratings with different frontside/backside reflectance.
abstract: A concept of two-dimensional periodic subwavelength gratings exhibiting different reflectance on the front and back sides is presented. This structure incorporates an arrangement of a metalized hole array and a nanodot array on top. We exemplify the optical properties for an aluminum grating with 243 nm period, and we demonstrate its color filtering properties for unpolarized light in reflectance as well as in transmittance yielding different colors for frontside and backside illumination. These findings have been confirmed by a numerical study. The gratings may be replicated by a simple nanoimprint process on plastic foils predestined for industrial mass production.
authors.affiliation: Louisenthal GmbH, Gmund, Germany.
authors.forename: Hans
authors.initials: H
authors.lastname: Lochbihler
authors.forename: Yan
authors.initials: Y
authors.lastname: Ye