Mesoscale engineering of photonic glass for tunable luminescence

Control of the optical behavior of active materials through manipulation of their microstructure has led to the development of high-performance photonic devices with enhanced integration density, improved quantum efficiencies and controllable color output. However, the achievement of robust light-harvesting materials with tunable, broadband and flattened emission remains a long-standing goal owing to the limited inhomogeneous broadening in ordinary hosts. Here, we describe an effective strategy for the management of photon emission by manipulating the mesoscale heterogeneities in optically active materials. Importantly, this unique approach enables control of dopant–dopant and dopant–host interactions on the extended mesoscale. This allows the generation of intriguing optical phenomena such as a high activation ratio of the dopant (close to 100%), dramatically inhomogeneous broadening (up to 480 nm), notable emission enhancement and, moreover, simultaneously extension of the emission bandwidth and flattening of the spectral shape in glass and fiber. Our results highlight that the findings connect the understanding of and manipulation in the mesoscale realm to functional behavior on the macroscale, and the approach to manage the dopants based on mesoscale engineering may provide new opportunities for the construction of a robust fiber light source. Manipulating the mesoscale structure enables broadband emission from glass and fibre optic cables. To produce compact light sources for applications such as broadband telecommunication and surgical microscopy, researchers are experimenting with glass and fibres with luminescent cores that are doped with transition-metal ions. Shifeng Zhou from the South China University of Technology and co-workers have discovered that medium-range interactions between dopants and their host matrix can significantly widen emitted wavelength ranges to give brighter, broader light sources. Applying mesoscale engineering approach for a tantalate glass system produced localized heterogeneous regions, which can isolate emission centres. The team demonstrated the potential of this pioneering strategy by constructing glass and optical fibre with tunable luminescent output, and extremely broad bandwidth up to ~480 nm which is the largest value ever reported in doped glass to date. A new principle for management of dopant–dopant and dopant–host interactions by manipulation of mesoscale heterogeneity in a single active material is presented. The proposed mesoscale engineering approach results in dramatically inhomogeneous broadening of dopant, and for the first time show success in simultaneously extending emission bandwidth and flattening spectral shape in a doped glass and fiber.