As the core component of this emerging field, the broadband NIR light source needs to be small and exquisite to meet the application requirements. Compared with traditional broadband NIR light sources such as the bulky tungsten-halogen lamps, broadband NIR phosphor-converted light-emitting diodes (NIR pc-LEDs) is proposed as an ideal compact light source due to their advantages of environmental protection, energy-saving, long lifetime, and small size. [2] The strategy of NIR pc-LEDs is mainly realized by coating broadband NIR phosphor on a blue LED chip. Among them, one of the important research topics is the exploration of broadband NIR phosphors that can be excited by blue light.Cr 3+ ion with d 3 electron configuration is the commonly used activator for NIR emitting phosphors. When it's located in a weak octahedral crystal field in a host, broadband NIR emission can be obtained due to the 4 T 2 → 4 A 2 transition. [3] The Cr 3+ -doped garnet phosphors are a typical broadband NIR luminescent material, showing high quantum efficiency and robust thermal stability. For example, Ca
An important challenge in the research and development of compact near-infrared (NIR) light sources is the discovery of new efficient ultra-broadband NIR luminescent materials to replace the conventional Cr 3+ -doped compounds. Herein, this work reports a divalent europium-doped Ba 3 GeO 4 Br 2 phosphor that exhibits a high photoluminescence quantum yield of 48.8% and an ultra-broad emission band ranging continuously from 500 to 1100 nm (full width at half maximum = 202 nm) under near-ultraviolet or blue light excitation. A strategy of embedding alumina crucible in high purity graphite crucible is devised and deployed during solid-state sintering to facilitate the conversion of Eu 3+ into Eu 2+ . Theoretical calculations, structural refinement, and spectral analysis demonstrate that the visible to NIR emission in Ba 3 GeO 4 Br 2 :Eu 2+ originates from the Eu 2+ ions occupying the distorted Ba3O 3 Br 4 polyhedra in the lattice. The as-prepared phosphor-converted light-emitting diode device achieves an optical output power of 30.1 mW@100 mA (520-1100 nm) and a photoelectric efficiency of 22%@100 mA (350-1100 nm). Experiments on tissue penetration and NIR imaging illustrate its application in spectral detection and food quality testing appears promising.
A novel mixed orthoborate–pyroborate phosphor, Ba2Sc2B4O11:Ce3+, with a bright broadband yellow-green emission peak at 540 nm was reported, which can be used for achieving full-spectrum white light illumination instead of a green phosphor.
Erbium ytterbium co-doped super-fluorescent fiber source (EYD-SFS) has been simulated by a theoretical model based on rate equations and power transfer equations. The output performances of four basic structures of EYD-SFS have been expressed, and it indicated that the DPF structure is a preferable structure. The dependence of output power, mean wavelength and bandwidth stability on the pump fiber length and the concentration of Er3+ and Yb3+ have also been studied. The results indicated with a proper doping concentration of Er3+ and Yb3+ of 6.0 × 1026 ions/m3 and 1.0 × 1027 ions/m3, the optimal gain fiber length is 3.6 cm. In this condition, good performances of DPF structure of EYD-SFS have been achieved.
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