Engineering Tunable Broadband Near‐Infrared Emission in Transparent Rare‐Earth Doped Nanocrystals‐in‐Glass Composites via a Bottom‐Up Strategy

Abstract

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.

Enhanced 2 µm Mid‐Infrared Laser Output from Tm3+‐Activated Glass Ceramic Microcavities

“…Considering that the average crystal size ( D ) is less than 25 nm and the selected pump wavelength ( λ ) is 808 nm in our experiment, which meets the condition of D / λ < 0.1, a Rayleigh scattering model is used to reveal the optical transmission features. [ 48 ] Based on the given model, the optical transmittance can be described as [ 49 ] where ε is the scattering loss, L is the optical transmission path, ρ is the density, m is the mass, λ 0 is the light wavelength in a vacuum, a is the radius of the crystal, n and n 0 are the refractive indexes of the crystal and glass host, respectively. The calculated results show that for a given transmission wavelength, the optical transmittance is inversely proportional to the crystal size (Figure 5g).…”

Emission Color Manipulation in Transparent Nanocrystals‐in‐Glass Composites Fabricated by Solution‐Combustion Process

“…A complete densification requires over 1000 °C for a conversion from silica gel to inorganic glass, which is detrimental to the embedding nanocrystals and their fluorescent efficiency . Although recently developed glass doping technology with robust thermal/chemical stability and outstanding fiber forming ability has overcome the limitations of the sol–gel process to some extent, thermal corrosion of the embedding nanocrystals in the high‐temperature (typically > 500 °C) cosintering process remains a significant challenge for building sophisticated nanostructure with controllable phase, composition, and morphology for high‐performance application . Another limitation concerns the color uniformity in the glass doping process.…”

Mid‐infrared luminesce of ZnS:Cr2+‐glass composite and fiber

“…Design and fabrication of new luminescent materials operating in the Mid‐IR region lies in the core of this topic . In order to obtain materials with broadband emission, many approaches such as codoped with rare‐earth ions, embedding Mid‐IR activators into chalcogenide glasses, etc., have been explored . Cr 2+ ‐doped II‐VI semiconductors such as ZnS and ZnSe exhibit a unique blend of physical, spectroscopic, and optical parameters, which has been recognized as an excellent Mid‐IR luminescent materials .…”

“…[9][10][11][12][13] In order to obtain materials with broadband emission, many approaches such as codoped with rare-earth ions, embedding Mid-IR activators into chalcogenide glasses, etc., have been explored. [14][15][16][17][18] Cr 2+ -doped II-VI semiconductors such as ZnS and ZnSe exhibit a unique blend of physical, spectroscopic, and optical parameters, which has been recognized as an excellent Mid-IR luminescent materials. 19 In this paper, we report the success in incorporation of ZnS:Cr 2+ into borophosphate glass and fabricate the corresponding composite (CZPB).…”