A subwavelength plasmonic grating with rectangular grooves on the metal surface is an efficient light trapper with
designer resonance position and angular bandwidth. In this work, a new method is presented, where the grooves are
filled with a dielectric resulting in a large shift of the resonance wavelength. A case study of a gold grating with grooves
18 nm wide and 47 nm deep is presented, where the resonance is shifted from original 720 nm to 960 nm by filling the
grooves with an n = 1.4 immersion oil.
We demonstrate 16 times increase in light absorption nano-structured metal compared to the flat surface by fabricating a
subwavelength grating on gold surface. This light-trapping phenomenon can be used in many areas from solar energy
conversion to photovoltaics. Here, we describe application to field enhancement in photocathodes where we show theoretically a performance increase of three orders of magnitude over conventional systems. We also describe the fabrication of these devices and present initial optical results.