16:00 〜 18:00
▲ [18p-P10-2] Characterization of two-photon exposure patterns in photoresist using photoluminescence quenching
キーワード：NANOPHOTONICS, METAMATERIALS
Recently, bi-anisotropic electromagnetic (EM) metamaterials based on 3D helical inclusions were proposed and realized experimentally for infra-red (IR) spectral ranges using Direct Laser Write (DLW) technique[1]. Helix-based perfect absorber (PA) metamaterials are fabricated using DLW in a dielectric photoresist, and the dielectric templates are subsequently metallized using sputtering by gold (Au). PA structures consisting of single micrometer-scale dielectric helices sputtered by about 30-50 nm thick Au film exhibit peak absorbance of 0.7-0.9 at IR wavelengths of 6-9µm. While absorbance bands can be tuned spectrally via templates choice of structural parameters of the dielectric, spectral tuning can be also achieved after the DLW fabrication via gradual increase of the coating thickness. Here we applicability and advantages of this approach. Figure 1 compares experimental absorbance spectra of a helical PA structure before and after the deposition of an additional ≈50 nm thick gold film. As can be seen, augmenting the Au thickness leads to a blue-shift of the absorbance peak wavelength by about 1.5µm. Physical origin and practical exploitation of this spectral shift for versatile post-DLW spectral tuning of PA structures will be discussed.