Fig. 4: Large-area holey nanophotonic devices.

a Schematic illustration of specific immune detection based on through nanohole arrays fabricated by the WEALTH technique. Insets, introduced –NH₂ group via bonding (3-Aminopropyl) trimethoxysilane (APTMS) with –OH group on the inner wall of YAG. (ii) SEM image of nanohole arrays. Inset, magnified SEM image of a nanohole. (iii) Cross-section microscope image of the nanohole. b Photoluminescence (PL) spectra of Rodamine B (RhoB) labeled detection antibody (dAb) in the nanohole arrays with various AR during specific detection. c PL spectra of specific dAb with antigen (Antigen-dAb) and non-specific dAb within phosphate buffer saline (PBS-dAb) detection. d Signal-to-noise ratio of PL between specific and non-specific detection in (c). e Reusability of a same nanohole sample for specific immunoassay. “High-T treated chip” means the biosensing chip was heat-treated at 1000 °C, to burn and vaporize of organic groups for next-cycle experiment. f Photograph of a large-area nanophotonic crystal device. g Geometric schematic of the designed large-area nanophotonic crystal. h SEM image of the fabricated large-area nanophotonic crystal device. i Transmittance spectra of large-area holey nanophotonic crystal devices fabricated with energies of 6, 8, and 10 μJ/pulse, respectively. Reference: transmittance spectrum without nanoholes on YAG. Blue and red arrows indicate the photonic band gap. Scale bars, 2 µm (a, ii), 200 nm (a, inset in ii), 50 µm (a, iii), and 1 µm (h).