Hyperbolic Metamaterials for Enhanced Scintillation
Scintillators are indispensable for the detection of X-rays, $γ$-rays, and energetic particles in applications ranging from medical imaging and security screening to high-energy physics. A major limitation of conventional scintillators is the inefficient extraction of scintillation photons caused by isotropic emission and total internal reflection at the scintillator--detector interface. Here, we propose and numerically investigate a grating-coupled hyperbolic metamaterial (HMM) in which the scintillation medium CsPbBr$_3$ forms one of the constituent layers. The proposed architecture simultaneously enhances spontaneous emission through broadband Purcell enhancement enabled by high-$k$ modes and improves optical extraction by directing the emitted radiation along the hyperbolic resonance cone, with a bullseye grating providing efficient far-field outcoupling. Finite-difference time-domain simulations predict broadband enhancement of the detected scintillation signal exceeding threefold across the CsPbBr$_3$ emission band, with a peak enhancement of approximately fivefold around the emission wavelength of 523 nm compared with an equivalent bulk scintillator. The proposed multilayer architecture is compatible with established thin-film deposition and nanofabrication techniques, robust against fabrication-induced layer-thickness variations, and scalable to accommodate larger volumes of scintillating material, providing a practical route toward high-performance scintillators for radiation detection and imaging applications.