Volumetric Nanophotonics for Enhanced Scintillation and Remote Light Outcoupling
Nanophotonic patterning is a promising approach to enhancing light extraction in scintillator materials, with the potential to improve performance in applications such as medical imaging and particle detection. While 2D surface patterns have been successful in improving scintillator performance, the true potential of nanophotonic patterning lies in the bulk, where photons are emitted, transported, and absorbed. Here, we experimentally demonstrate the enhancement and control of scintillation using 2.5D volumetric nanophotonic patterns. Using a direct femtosecond laser writing approach, we nanofabricate square lattices of air holes into the bulk of inorganic scintillators (YAG:Ce and YAG:Yb), achieving nearly subwavelength periods compared to the peak emission wavelength and depths up to hundreds of microns, which fill a large fraction of the full thickness of the bulk. Under high-energy excitation, the patterns appear up to ~3.5$\times$ brighter and demonstrate emission enhancement trends consistent with well-established nanophotonic scaling laws. We also report a novel functionality we call "remote outcoupling," in which the nanophotonic patterns emit light that is generated in another region of the scintillator, without being directly excited themselves. Our monolithic nanofabrication approach extends nanophotonic scintillators into the bulk, which is an important step towards total control over scintillation using photonic design.