Broadband Near-Infrared Cr4+-Doped Garnet Phosphors through Divalent Calcium Charge Compensation for Advanced Crystal Fiber Amplifiers

Near-infrared-II (NIR-II) phosphors are extensively used as NIR phosphor-converted light-emitting diodes across various applications. Nonetheless, their application in fiber communication remains underexplored. Furthermore, efficiency challenges persist in developing broadband NIR crystal fiber amplifiers. A series of the Y3−yAl5−xO12:xCr,yCa2+ phosphors with boosted Cr4+ concentration via calcium charge compensation is synthesized, and the optimized sample is fabricated to crystal fibers to reveal the application of the NIR-II phosphors to fiber communication. The fabricated Cr4+-doped crystal fiber, exhibiting broadband Cr4+ emission within 1100–1600 nm, effectively covers the high-transmission loss region caused by water absorption in the telecommunication band. Comprehensive characterization and analyses of the Cr4+ are discussed. Y2.84Al4.9O12:0.1Cr,0.16Ca2+ crystal fiber, fabricated through phosphor synthesis, pellets’ production, and the laser-heated pedestal growth method, exhibits superior photoluminescence compared to the commercial Cr4+-doped Y3Al5O12 crystal fiber. Here the potential of NIR-II phosphors is highlighted in enhancing fiber communication and valuable insights for their future application are provided. That dataset provides the raw data of room-temperature excitation and emission spectra and decay profiles, temperature-dependent photoluminescence and decay profiles, and high-pressure-dependent photoluminescence of Y3−yAl5−xO12:xCr,yCa2+.