Dielectric-engineered plasmonic nano-hole arrays (NHAs) offer an effective approach for precisely controlling subwavelength light confinement. Here, we investigate wavelength compression in aluminum NHAs filled with three different dielectric materials such as Al2O3, MoO3, and TiO2 under illumination by a 1.5 µm lightwave. The hole radius varies from 300 nm to 500 nm to analyze the combined effects of geometry and dielectric environment on the plasmonic response. The NHAs filled with Al2O3 exhibit a pronounced and monotonic increase of the compressed wavelength with decreasing hole radius, indicating strong geometric tunability of the dominant plasmonic mode. Meanwhile, the structures filled with MoO3 or TiO2 show weak wavelength variations over the same radius range. Spatially resolved analysis at these nano-holes reveals nearly position-independent wavelength squeezing for Al2O3, whereas noticeable spatial variations appear for MoO3 and TiO2 at hole radii of 450 nm and 400 nm, respectively. The observed wavelength compression is attributed to hybrid plasmonic modes originating from the interplay between in-hole-like compressed cavity modes and localized surface plasmon polaritons. Our findings demonstrate how dielectric composition tunes wavelength compression in plasmonic NHAs, offering practical guidelines for designing the near-infrared plasmonic devices.
Jeong et al. (Sat,) studied this question.