We demonstrate more advanced length scaling method of aluminum based nanoantennas using waveguide theory and well defined dielectric constant of metals in extremely high frequency such as visible to near-infrared regions (wavelengths from 400 nm to 3000 nm). To verify that our simulation for length scaling is effective in visible to near infrared regions, we fabricated dipole nanoantennas. Furthermore, it is found that experimental results for nanoantenna arrays support our model.
A nanostructure which induces localized surface plasmon resonance (LSPR) can be utilized in visible light and near infrared (NIR) regions and it shows promising features as a bio-detector because LSPR state is changed easily by different bio-related materials. Owing to transparent property of many biomolecules as well as diluted states in base solutions, it is hard to distinguish each other by eye or microscope analysis. However, difference in molecular structure and composition makes difference in optical characteristics such as a refractive index or a dielectric constant. Therefore, our LSPR-based nanohole array structure which has high sensitivity to detect small changes in optical characteristics can be a great candidate for a bio detector. Here, we fabricated structural color filters (SCFs) to detect wavelength shifts for several biomolecules and optimized the nanohole array structures for high sensitivity. Periodic nanohole arrays were designed to present resonance peaks in visible light region for optical analysis and fabricated in Au or Al thin film layer. The spectral shifts were detected caused by biomolecules.