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.
© 2013 Optical Society of America
Original Manuscript: September 19, 2012
Revised Manuscript: February 19, 2013
Manuscript Accepted: February 19, 2013
Published: March 20, 2013
Hans Lochbihler and Yan Ye, "Two-dimensional subwavelength gratings with different frontside/backside reflectance," Opt. Lett. 38, 1028-1030 (2013)