Boosting fluorescence efficiency via filling technique prepared photonic crystal composites.

Au-doped photonic crystals offer considerable potential for boosting optical signals, however, precisely controlling the distance between luminescent particles and Au nanoparticles (NPs) faces severe challenges. We proposed a "filling" technique to prepare porous Au-doped inverse-opal PC (IOPC) with encapsulated Au NPs uniformly dispersing in insulating silica. The effective separation between Au NPs and infiltrated luminescent quantum dots successfully addresses the issue of fluorescence quenching, enhancing the photoluminescence intensity by 106-fold. Additionally, the double-layer IOPC-OPC composite, integrating an Au-doped IOPC and an opal photonic crystal (OPC) completely reflecting excitation or emission light, significantly improves the fluorescence intensity to 242-fold, far superior to the published counterparts. This synergy of localized surface plasmon resonance, high density of state, and photonic band gap in the IOPC-OPC composite offers an effective and low-loss approach for the precise modulation and amplification of photoluminescence. This strategy is crucial for the development of next-generation optical devices with improved sensitivity and stability.