摘要： Applications of trivalent rare earth (RE3+)-doped light sources in solid-state laser technology, optical communications, biolabeling, and solar energy management have stimulated a growing demand for broadband emission with flexible tunability and high efficiency. Codoping is a conventional strategy for manipulating the photoluminescence of active RE3+ ions. However, energy transfer between sensitizers and activators usually induces nonradiative migration depletion that brings detrimental luminescent quenching. Here, a transparent framework is employed to assemble ordered RE3+-doped emitters to extend the emission spectral range by extracting photons from a variety of RE3+ ions with sequential energy gradient. To block migration-mediated depletion between different RE3+ ions, a nanoscopic heterogeneous architecture is constructed to spatially confine the RE3+ clusters via a 'nanocrystals-in-glass composite' (NGC) structure. This bottom-up strategy endows the obtained RE3+-doped NGC with high emission intensity (nearly one order of magnitude enhancement) and broadband near-infrared emission from 1300 to 1600 nm, which covers nearly the whole low-loss optical communication window. Most crucially, NGC is a versatile approach to design tunable broadband emission for the potential applications in high-performance photonic devices, which also provides new opportunities for engineering multifunctional materials by integration and manipulation of diverse functional building units in a nanoscopic region.