Giant Red-Shifted Emission in (Sr,Ba)Y2O4:Eu2+ Phosphor Toward Broadband Near-Infrared Luminescence

Near-infrared (NIR) light-emitting diodes (LEDs) light sources are desirable in photonic, optoelectronic, and biological applications. However, developing broadband red and NIR-emitting phosphors with good thermal stability is always a challenge. Herein, the synthesis of Eu²⁺-activated SrY₂O₄ red phosphor with high photoluminescence quantum efficiency and broad emission band ranging from 540 to 770 nm and peaking at 620 nm under 450 nm excitation is designed. Sr/Ba substitution in SrY₂O₄:Eu²⁺ has been further utilized to achieve tunable emission by modifying the local environment, which facilitates the giant red-shifted emission from 620 to 773 nm while maintaining the outstanding thermal stability of SrY₂O₄:Eu²⁺. The NIR emission is attributed to the enhanced Stokes shift and crystal field strength originated from the local structural distortions of [Y1/Eu1O₆] and [Y2/Eu2O₆]. The investigation in charge distribution around Y/Eu provides additional insight into increasing covalency to tune the emission toward the NIR region. As-fabricated NIR phosphor-converted LEDs demonstration shows its potential in night-vision technologies. This study reveals the NIR luminescence mechanism of Eu²⁺ in oxide-based hosts and provides a design principle for exploiting Eu²⁺-doped NIR phosphors with good thermal stability.     

Strong Self-Trapped Exciton Emission and Highly Efficient Near-Infrared luminescence in Sb3+-Yb3+ Co-doped Cs2AgInCl6 Double Perovskite

Yb³⁺ doped lead-free double perovskites (DPs) with near-infrared (NIR)-emitting have attracted extensive attention due to their wide application prospects. Unfortunately, they still suffer from weak NIR emission due to undesirable resonance energy transfer between the sensitizers and Yb³⁺ ions. Herein, a new effective NIR-emitting DP is developed by co-doping Sb³⁺ and Yb³⁺ into Cs₂AgInCl₆. Experiments and theoretical calculations reveal that induced by co-doping Sb³⁺ ions, the self-trapped excitation (STE) emission intensity of Cs₂AgInCl₆ is greatly enhanced by 240 times, and the STE emission shifts from 600 nm to 660 nm, which contributes to a larger spectral overlap between STE emission and the absorption of Yb³⁺ ions. As a result, the absolute NIR photoluminescence quantum yield reaches an unprecedented 50% in lead-free DPs via high-efficiency STE sensitization (>30%). The excellent optical performance of Cs₂AgInCl₆: Sb, Yb with high ambient, thermal and light stability makes it suitable for application in night-vision devices. Moreover, an ingenious dual-modal optical information encryption based on the combination of visible and NIR fluorescence printing patterns utilizing Cs₂AgInCl₆: Sb and Cs₂AgInCl₆: Sb, Yb respectively is successfully demonstrated. This study provides inspiration for designing highly efficient NIR-emitting Ln³⁺-doped DPs and illustrates their great potential in versatile optoelectronic applications.     

Tb3+-Yb3+离子对的近红外量子剪裁进展研究

近红外量子剪裁能够有效地提高硅太阳能电池的效率。稀土元素种类繁多,能级丰富,常被用于制作近红外量子剪裁发光材料。研究者们用适当的方法制成发光材料之后,测量材料的吸收光谱,激发光谱和发射光谱。根据这些数据计算得到材料的量子效率。其中Tb3+-Yb3+离子对备受关注。Tb3+吸收紫外-可见光,通过协同能量传递把能量传递给Yb3+离子。Yb3+离子跃迁辐射出1000nm左右的近红外光。该波段的光子能够被硅太阳能电池吸收利用。Tb3+-Yb3+离子对在不同掺杂浓度,不同基质中得到的量子效率不同。     

Sb~(3+)掺杂的YAG:Ce荧光粉的合成与发光性能研究

通过高温固相法制备了白光LED用Sb3+掺杂的Y1.94-yGdSbyAl5O12:0.06Ce荧光粉,使用荧光分光光度计研究了样品的发光性能,并采用紫外-可见-近红外光谱分析系统分析了所制荧光粉的封装性能。结果表明,Y1.94-yGdSbyAl5O12:0.06Ce荧光粉为立方晶系,其发射中心波长为550 nm,Sb3+掺杂有助于提高YAG:Ce的发光强度。将合成的Y1.92GdSb0.02Al5O12:0.06Ce(CL-Y-550)荧光粉封装成白光LED,其平均色温为5 376 K,属于冷白;平均显色指数为81.2,达到了基本的应用水平。     

掺Er~（3＋）和掺Er~（3＋）／Yb~（3＋）光纤中1313nm到780nm的频率上转换过程

研究了在连续锁模和调Ｑ锁模两种脉冲泵浦条件下，掺Ｅｒ（３＋）和掺Ｅ３＋／Ｙｂ３＋单模ＧｅＯ２／ＳｉＯ２石英光纤中，１３１３ｎｍＮｄ：ＹＬＦ激光到７８０ｎｍ波长的频率上转换过程。Ｅｒ３＋离子在共振吸收两个光子后到４Ｆ９／２态，再经快速的无辐射转移到４Ｉ９／２态．形成７８０ｎｍ辐射。在连续锁模泵浦条件下．１３１３ｎｍ至７８０ｎｍ的转换效率比调Ｑ锁模条件下更高．而后者的峰值功率是前者的几百倍。     

基于掺铒光纤放大自发辐射的宽带光源优化研究

提出并设计了一种双向泵浦、双程结构的掺铒光纤放大自发辐射宽带光源。对该光源的实现方案和优化效果进行了实验研究,并分析了该光源的输出功率转化效率、光谱平坦度以及工作稳定性。结果表明,和前向泵浦ASE输出相比,该结构所产生的宽带光源泵浦转化效率提高8.24%,在不加任何滤波器条件下1 525～1 557 nm之间光谱平坦度提升1 dB,3 dB线宽增加24.56 nm。实现了1 h内光功率和光谱的稳定输出,可为光纤传感、光谱分析等领域提供光源。     

Er^3＋掺杂玻璃的1．5μm发射光谱及其带宽

用高温熔融法制备了Er^3 掺杂的氧化物玻璃，研究了Er^3 在11～300K温度范围内对应于^4I13/2→^4I15/2跃迁的1．5μm发射光谱，将^4I13/2多重态中的高能态和最低能态向基态跃迁发射的光谱成分从测量的发射光谱中分离开来，讨论了光谱成分对1．5μm发射带宽的影响。提出了等效四能级模型，并用此模型解释了Er^3 ^4I13/2→^4I15/2辐射跃迁的线形及其变温特性。分析表明，提高^4I13/2多重态中高能态的辐射跃迁几率是获得室温下宽带1．5μm发射的关键。最后，根据Mc Cumber理论，利用吸收光谱变换得到了与测量一致的发射光谱形状及相应的受激发射截面。