Sunlight‐Induced Cross‐Linked Luminescent Films Based on Polysiloxanes and d‐Limonene via Thiol–ene “Click” Chemistry

The increasing pursuit of biocontained elastic materials led the investigation of the potential use of the monoterpene limonene in film synthesis via thiol–ene reaction. Poly[(mercaptopropyl)methylsiloxane] (PMMS) is first synthesized. By controlling the molar ratio of PMMS and functional monomers, such as polyethylene glycol allyl methyl ether or rhodamine‐B, PMMS is partially functionalized while leaving spare mercapto groups that could be further used as cross‐linking sites. On the basis of the functionalized PMMS, novel transparent silicone luminescent films with hydrophilic tunable properties are prepared by natural‐sunlight‐triggered thiol–ene “click” chemistry by using d ‐limonene as a cross‐linker. Their structures and properties are thoroughly characterized. Transparent luminescent films are coated on commercially available UV‐light emitting diode (LED) cell from solution medium followed by an in situ cross‐linking step; a colorful LED cell is obtained through this facile and efficient method. The UV‐LED coated by films show very intense photoluminescence under normal visible light or the light is on, and has very high coloric purity.     

电离气体选择性激发产生变色发光的研究

本文综述我们对电脑气体选择性激发产生变色发光的理论研究和实验研究，并探讨这种类型变色发光的实际应用。     

溅射和激光淀积的ZnO多晶薄膜的结构和发光性质

我们分别通过直流反应溅射及脉冲激光淀积法制备了ZnO多晶薄膜。X射线衍射结果显示出薄膜的c轴取向。原子力显微镜证实薄膜的多晶结构。两种方法制备的ZnO在光子激发下都发射较强的带边荧光。绿色荧光未被观察到。激光淀积在(001)硅表面的ZnO的发光源自“自由激子”辐射。激光淀积在(0001)氧化铝晶体表面的ZnO的发光机制则在相当宽的激发强度范围内都呈现出电子．空穴等离子体(electron-hole plasma)的复合特性。     

Ultralong Near Infrared Room Temperature Phosphorescence in Cu(I) Metal-Organic Framework Based-on D–π–A–π–D Linkers

Materials taking abundant advantage of triplet states luminescence have risen lots of attention in decades. In this work, a Cu(I) metal-organic framework (MOF) with synchronous metal-to-ligand charge transfer (MLCT) state and triplet emission of the ligand is synthesized from a D–π–A–π–D ligand with suitable energy gap. The Cu(I) MOF possessed MLCT emission in the range of 450–505 nm with microsecond lifetimes (1.07 to 5.38 µs) and a triplet state emission in near infrared (NIR) region ≈705 nm with lifetimes of 1.85 ms at 300 K and 25.16 ms at 77 K, much longer than those of reported Cu(I) MOFs. Moreover, a white light is obtained through adjusting the relative intensity of dual peaks. More importantly, NIR long persistent luminescence of Cu-MOF is observed by naked eyes under cryogenic condition. Multiple factors such as the delicate design of the D–π–A–π–D structure of ligand, the enhanced spin-orbital coupling by Cu(I) networks, and the tight packing mode of the framework promote the generation of MLCT emission and ultralong NIR room temperature phosphorescence. The combination of calculation and experiment to analyse the luminescence mechanism of Cu(I) MOFs provides ideas for the development of Cu(I)-based intelligently responsive materials with RTP properties.     

Liquid Nitrogen Temperature Mechanoluminescence and Persistent Luminescence

As novel stress-sensing materials, the reported mechanoluminescence (ML) phosphors work only at or above room temperature. Herein, the ML response to low temperatures (77 K) is extended by employing ultra-shallow traps. Strong ML stimulated by handwriting force followed by persistent luminescence is observed in BaSi₂O₂N₂:Eu²⁺ (BSON) at 77 K. The UV pre-irradiated BSON can still keep the characteristics of ML with 45% intensity after 300 min. Abundant ultra-shallow traps with depth of ≈0.19 eV are found and revealed to be responsible for the low-temperature ML and persistent luminescence. Manipulation of the ultra-shallow traps is realized by doping Ge, Er, and Ce ions in BSON, leading to significant ML enhancement at 77 K. Together with ML, the ultra-shallow traps also exhibit force memory ability to replicate the pre-applied force pattern simply by afterglow. The finding advances the state-of-the-art in force sensing under low temperature conditions.     

Tunable Emission in Heteroepitaxial Ln‐SURMOFs

By using a layer‐by‐layer (LbL) approach, lanthanide‐based, monolithic metal–organic framework (MOF) thin films are fabricated for optical applications. In particular, the LbL approach allows manufacturing of heteroepitaxial Tb(III)‐Eu(III)(BTC) coatings with precise thickness control. Adjusting the Tb(III)‐to‐Eu(III) ratio allows tuning of the emission color. The hetero‐multilayer architecture makes it possible to suppress the direct Tb(III)‐to‐Eu(III) energy transfer, an unwanted phenomenon present in the corresponding mixed‐metal bulk MOF structures. The resulting Ln‐MOF thin films, or Ln‐surface‐anchored MOFs (SURMOFs), are characterized by X‐ray diffraction, infra‐red reflection absorption spectroscopy, UV–vis, and photoluminescence measurements. The results demonstrate that the heteroepitaxial SURMOF architectures carry huge potential for fabricating optical coatings for a wide range of applications.     

Compact VDTA-based current-mode electronically tunable universal filters using grounded capacitors

This paper presents a compact current-mode three-input single-output (TISO) type universal filter. Only one voltage differencing transconductance amplifier (VDTA) and two grounded capacitors are employed in the proposed filter. The circuit can realize lowpass, bandpass, highpass, bandstop and allpass biquadratic filter outputs by connecting the appropriate inputs, and offers electronic control of the natural angular frequency (ω₀) and quality factor (Q) by means of adjusting the transconductance gain of the VDTA. In addition, by slight modification of the proposed scheme, another more useful TISO construction with orthogonal ω₀–Q tuning has been obtained. Both the discussed universal filters have been shown to have low incremental active and passive sensitivities. To demonstrate the performances of the filters and verify the theoretical analysis, computer simulations are accomplished with the PSPICE program.     

蓝色荧光粉K(Na)BaBP2O8:Eu2+的制备与发光特性

采用高温固相法在还原气氛中合成K(Na)BaBP₂O ₈:Eu²⁺系列硼磷酸盐蓝色荧光粉,研究煅烧温度 以及用Na⁺掺杂替换K⁺对荧光粉晶体结构和发光性能的影响。利用热重-示差扫描量热 (TG-DSC)、X射 线衍射(XRD)、荧光(PL)光谱和色坐标(CIE)等手段确定了 荧光粉的合成温度,并对荧光粉的晶体 结构和发光性能进行表征。结果表明,800～875℃制备的KBaBP₂O ₈:0.03Eu²⁺荧光粉具有KBaBP₂O₈纯相 结构,属于四方晶系,空间群I42d,荧光粉的最佳合 成温度为875℃。K(Na)BaBP₂O₈:Eu²⁺系列荧光粉 可被波长为365nm的近紫外光有效激发,与InGaN芯片( 350~410nm)相匹配;其发射光谱为 400~650nm的不对称宽带,发射峰位于456nm 左右,对应Eu²⁺的4f^65d1-4f⁷-5d⁰跃迁。利用van Uitert经 验公式计算了Eu²⁺取代KBaBP₂O₈中Ba²⁺和K⁺时所占的晶体学格位,得出 449.4nm、439.1nm两个发射属 于Eu²⁺占据8配位的Ba²⁺和K⁺的5d-4f跃迁发射 ,511.0、506.7nm两个发射属于Eu²⁺ 占据6配位的 Ba²⁺和K⁺的5d-4f跃迁发射。用适量Na⁺替换K⁺可 以明显提高荧光粉的发光强度,其最佳掺杂摩尔比例为 Na/K=0.35/0.65,此时荧光粉的主晶相没有改变,但XRD衍射峰向大角度方向偏移。K(Na)Ba BP₂O₈:Eu²⁺ 荧光粉的CIE点可落在从蓝光到蓝白光区域,在近紫外LED应 用中可以根据实际需要灵活选择。     

从OFC2001看世界光纤通信的新发展

文中报道了OFC2001会议的概况,并从光纤传输系统、宽波段光放大器、可调谐光源技术,阵列波导光栅、偏振模色散的研究和补偿技术五个方面来介绍光纤通信的最新发展。     

空间级联可调谐光滤波器方式实现光分插复用器

提出一种采用空间级联可调谐光滤波器方式实现的OADM.该器件不但具有集成度高、体积小、插入损耗低、信道间插入损耗差异小的特点,而且能够在控制电路的作用下灵活选择上下路波长及其数量,为构建灵活、高性能的WDM网络提供了选择.