Enhanced emission of 2.9 μm from Ho3+/Pr3+ co-doped LiYF4 crystal excited by 640 nm

The use of Pr3+co-doping for great enhancement of mid-infrared(mid-IR) emissions at 2.9 μm and 2.4 μm is investigated in the Ho3+/Pr3+co-doped LiYF4 crystals.With the introduction of Pr3+ions,the fluorescence lifetime of Ho3+:5I7 level is 2.15 ms for Ho3+/Pr3+co-doped crystal,and the lifetime for Ho3+singly doped crystal is 17.70 ms,while the lifetime of Ho3+:5I6 level decreases slightly from 2.11 ms for Ho3+:LiYF4 to 1.83 ms for Ho3+/Pr3+:LiYF4.It is also demonstrated that the introduction of Pr3+greatly increases the mid-infrared emission of Ho3+:5I6 →5I7 which depopulates the Ho3+:5I7 level,while it has little influence on the Ho3+:5I6 level,which is beneficial for greater population inversion and laser operation.The analysis on the decay curves of the 2.0 μm emissions in the framework of the Inokuti-Hirayama model indicates that the energy transfer from Ho3+to Pr3+is mainly from electric dipole-dipole interaction.The calculated efficiency of energy transfer from Ho3+:5I7 to Pr3+:3F2 level is 87.53% for Ho3+/Pr3+(1.02%/0.22%) co-doped sample.Our results suggest that the Ho3+/Pr3+co-doped LiYF4 single crystals may have potential applications in mid-IR lasers.     

Enhancement of fluorescence emission and signal gain at 1.53 µm in Er3+/Ce3+ co-doped tellurite glass fiber

Er3+/Ce3+ co-doped tellurite glasses with composition of TeO2-GeO2-Li2O-Nb2O5 were prepared using conventional melt-quenching technique for potential applications in Er3+-doped fiber amplifier (EDFA). The absorption spectra, up-conversion spectra and 1.53 µm band fluorescence spectra of glass samples were measured. It is shown that the 1.53 µm band fluorescence emission intensity of Er3+-doped tellurite glass fiber is improved obviously with the introduction of an appropriate amount of Ce3+, which is attributed to the energy transfer (ET) from Er3+ to Ce3+. Meanwhile, the 1.53 µm band optical signal amplification is simulated based on the rate and power propagation equations, and an increment in signal gain of about 2.4 dB at 1 532 nm in the Er3+/Ce3+ co-doped tellurite glass fiber is found. The maximum signal gain reaches 29.3 dB on a 50 cm-long fiber pumped at 980 nm with power of 100 mW. The results indicate that the prepared Er3+/Ce3+ co-doped tellurite glass is a good gain medium applied for 1.53 µm broadband and high-gain EDFA.     

Enhancement of 2.0 µm fluorescence emission in new Ho3+/Tm3+/Yb3+ tri-doped tellurite glasses

For enhancing the 2.0 µm band fluorescence of Ho3+, a certain amount of WO3 oxide was introduced into Ho3+/Tm3+/Yb3+ tri-doped tellurite glass prepared using melt-quenching technique. The prepared tri-doped tellurite glass was characterized by the absorption spectra, fluorescence emission and Raman scattering spectra, together with the stimulated absorption, emission cross-sections and gain coefficient. The research results show that the introduction of WO3 oxide can further improve the 2.0 µm band fluorescence emission through the enhanced phonon-assisted energy transfers between Ho3+/Tm3+/Yb3+ ions under the excitation of 980 nm laser diode (LD). Meanwhile, the maximum gain coefficient of Ho3+ at 2.0 µm band reaches about 2.36 cm-1. An intense 2.0 µm fluorescence emission can be realized .     

Ho3+/Pr3+共掺氟化铝基玻璃光纤2.86 μm激光性能研究 （特邀）

文中使用熔融淬火法制备了氟化铝基、氟化铟基和氟化锆基玻璃样品,通过浸水实验研究了其抗潮解稳定性,结果表明氟化铝基玻璃具有更好的抗潮解性能。因此制备了不同浓度的Ho3+/Pr3+共掺氟化铝基玻璃样品,测试了其透过光谱,表明该玻璃具有高的透过率和宽的透过窗口。在1 150 nm拉曼激光的激发下,获得了样品的发射光谱,并对其发光机理进行了分析。利用吸注法制备了2 Ho3+/0.2 Pr3+掺杂的氟化铝基玻璃预制棒,使用棒管法拉制了氟化铝基玻璃光纤。使用回切法测得光纤在793 nm处的损耗为1.8 dB/m。在1 150 nm激光泵浦下,利用8.6 cm长的Ho3+/Pr3+共掺氟化铝基玻璃光纤作为增益介质,获得了功率为207 mW的2.865 μm激光输出,斜率效率为11.4%。上述研究结果表明,氟化铝基玻璃光纤是一种稳定的中红外激光增益材料。     

Improvement of 1.53 μm emission and energy transfer of Yb3+/Er3+ co-doped tellurite glass and fiber

To improve the 1.53 μm band emission of Er³⁺, the trivalent Yb³⁺ ions were introduced into the Er³⁺ single-doped tellurite glass with composition of TeO₂–ZnO–La₂O₃, a potential gain medium for Er³⁺-doped fiber amplifier (EDFA). The improved effects were investigated from the measured 1.53 μm band and visible band spontaneous emission spectra together with the calculated 1.53 μm band stimulated emission (signal gain) spectra under the excitation of 975 nm laser diode (LD). It was found that Yb³⁺/Er³⁺ co-doping scheme can remarkably improve the visible band up-conversion and the 1.53 μm band fluorescence emission intensity, and meanwhile improves the 1.53 μm band signal gain to some extent, which were attributed to the result of the effective energy transfer of Yb³⁺:²F_5/2 + Er³⁺:⁴I_15/2 → Yb³⁺:²F_7/2 + Er³⁺:⁴I_11/2. The quantitative study of energy transfer mechanism was performed and microscopic energy transfer parameters between the doped rare-earth ions were determined. In addition, the spectroscopic properties of Er³⁺ were also investigated from the measured absorption spectrum according to the Judd–Ofelt theory, and the structure behavior and thermal stability of the prepared tellurite glass were analyzed based on the X-ray diffraction (XRD) and differential scanning calorimeter (DSC) measurements, respectively.     

Structure and spectroscopic properties of Er3+/Ce3+ co-doped TeO2-Bi2O3-TiO2 glasses modified with various WO3 contents for 1.53 μm emission

The Er^3＋/Ce^3＋ co-doped tellurite-based glasses （TeO2-Bi2O3-TiO2） modified with various WO3 contents are prepared using conventional melt-quenching technique. The X-ray diffraction （XRD） patterns and Raman spectra of glass sam- ples are measured to investigate the structures. The absorption spectra, the up-conversion emission spectra, the 1.53 /am band fluorescence spectra and the lifetime of Er3＋：4113/2 level are measured, and the amplification quality factors of Er3＋ are calculated to evaluate the effect of WO3 contents on the 1.53 μm band spectroscopic properties. With the in- troduction of WO3, it is found that the prepared tellurite-based glasses maintain the amorphous structure, while the 1.53 μm band fluorescence intensity of Er3＋ is improved evidently, and the fluorescence full width at half maximum （FWHM） is broadened accordingly. In addition, the prepared tellurite-based glass samples have larger bandwidth qual- ity factor than silicate and germanate glasses. The results indicate that the prepared Er3＋/Ce3＋ co-doped tellurite-based glass with a certain amount of WO3 is an excellent gain medium applied for the 1.53 μm band Er3＋-doped fiber ampli- fier （EDFA）.     

Influence of Yb2O3 on the 1.53 μm spectroscopic properties in Er3+/Ce3+ co-doped TeO2-WO3-Na2O-Nb2O5 glasses

The Yb2O3 component was introduced into the Er3+/Ce3+ co-doped tellurite glasses with the composition of TeO2-WO3-Na2O-Nb2O5 to study the effect of Yb3+ on the 1.53 μm spectroscopic properties of Er3+. The X-ray diffraction (XRD) curve and Raman spectrum were measured to investigate the structure nature of synthesized tellurite glasses. The absorption spectrum, upconversion emission spectrum and fluorescence spectrum were measured to evaluate the improved effect of Yb3+ concentration on the 1.53 µm band fluorescence of Er3+. Results of the measured 1.53 µm band fluorescence intensity show a significant improvement with the increase of Yb3+ concentration, while the total quantum efficiency reveals a similar increasing trend. The results of the present work indicate that Er3+/Ce3+/Yb3+ tri-doped tellurite glass has good prospect as a promising gain medium applied for the 1.53 µm broadband amplifier.     

同带泵浦Ho3+激光晶体1.2 μm 波段红外激光阈值功率

为探索同带泵浦掺杂Ho3+激光晶体1.2 μm波段红外激光输出, 采用掺杂浓度为1 at%的Ho3+: LLF激光晶体作为激光增益介质, 应用两种典型准三能级理论模型, 计算了Ho3+在5I6和5I8 能级间跃迁辐射1.19 μm激光的阈值功率, 分析了泵浦光和激光束腰半径、激光晶体长度、吸收损耗、腔镜反射率等参量与阈值功率的变化关系, 得出了吸收损耗是影响阈值功率最敏感因素的重要结论, 确定了泵浦阈值功率的范围, 为后续1.2 μm波段红外激光实验研究提供了可靠的理论参考数据.     

Nd3+ doped fluorochlorozirconate glass:3.9 μm MIR emission properties and energy transfer

The Nd3+ doped fluorochlorozirconate (FCZ) glass was prepared by melt-quenching method. The 3.9 μm emission from Nd3+ ions is attributed to the two-photon absorption process. The strong emission transition at 3.9 μm fluorescence peak intensity, corresponding to the 4G11/2→2K13/2 transition, is directly proportional to the NaCl concentration. With the increase of the Cl- ions amount, the mid-infrared (MIR) luminescent intensity is significantly enhanced. Additionally, the Judd-Ofelt (J-O) parameter Ω2 is larger than that of the fluorozirconate (FZ) glass, which indicates the covalency of the bond between RE ions and ligand is stronger as Cl- ions substitution of F- ions in chloride FZ glass. The X-ray diffraction (XRD) patterns show that the amorphous glassy state keeps the FZ glass network structure. In brief, the advantageous spectroscopic characteristics make the Nd3+-doped FCZ glass be a promising candidate for application of 3.9 μm emission.     

Pr3+/Yb3+共掺1.3μm锆系氟化物玻璃光纤的研制

本文通过引入Ｙｂ＾３＋离子以提高掺镨光纤的泵浦效率和改善高浓度掺杂下的浓度猝灭效应。阐述了掺Ｐｒ＾３＋氟化物玻璃光纤的工艺并对掺Ｐｒ＾＾３＋／Ｙｂ＾３＋光纤的光谱特性进行了研究。     

Er3+:Yb3+:GdAl3(BO3)4晶体1.5～1.6 μm波段激光性能

采用熔盐法获得了Yb3 和Er3 离子原子数分数分别为20%和1.1%的GdAl3(BO3)4(简称GAB)晶体.在平-凹谐振腔中,利用0.97μm波长光纤耦合准连续(CW)半导体激光端面抽运0.7 mm厚的该晶体,当输出镜透过率为1.5%时,获得斜率效率为20%,最高功率为1.75 W的1.5~1.6μm波段激光输出.输出激光波长随吸收抽运功率和输出镜透过率发生变化.当输出镜透过率为1.5%时,随着吸收抽运功率的增加,不仅起振的纵模带增加并且输出功率逐渐从1.60μm的纵模带中转移到1.55μm的纵模带中.而当吸收抽运功率为13.6 W时,随着输出镜透过率的增加,输出激光波长从1.60μm转移到1.52μm.结果表明Er3 和Yb3 双掺的GAB晶体是一种优秀的1.5~1.6μm波段激光材料.     

Performance of Er3+-doped chalcogenide glass MOF amplifier applied for 1.53 μm band

A model of Er3＋-doped chalcogenide glass （GasGe20Sb10S65） microstructured optical fiber （MOF） amplifier under the excitation of 980 nm is presented to demonstrate the feasibility of it applied for 1.53 μm band optical communications. By solving the Er3＋ population rate equations and light power propagation equations, the amplifying performance of 1.53 μm band signals for Er3＋-doped chalcogenide glass MOF amplifier is investigated theoretically. The results show that the Er6＋-doped chalcogenide glass MOF exhibits a high signal gain and broad gain spectrum, and its maximum gain for small-signal input （-40 dBm） exceeds 22 dB on the 300 cm MOF under the excitation of 200 mW pump power Moreover, the relations of 1.53 μm signal gain with fiber length, input signal power and pump power are analyzed. The results indicate that the Er3＋-doped Ga5Ge20Sb10S65 MOF is a promising gain medium which can be applied to broadband amplifiers operating in the third communication window.     

Effect of Ce2O3 on the 1.53 μm spectroscopic properties in Er3+-doped tellurite glasses

The crown-like zinc oxide(Zn O)samples,which are composed of a hexagonal cap and a tower-like shaft,are prepared by vapor transport method.The hexagonal cap,working as a whispering gallery mode(WGM)resonant cavity,demonstrates density-dependent ultraviolet(UV)lasing emission with a broadened and squared photoluminescence(PL)profile under UV excitation at 355 nm.Theoretical analyses based on Fermi golden rule show that the broadened spectrum profile results from the special optical mode density characteristics in a WGM micro-cavity,which is in agreement with the observed results.     

Effect of Ce2O3 on the 1.53 μm spectroscopic properties in Er3+-doped tellurite glasses

Er3+/Ce3+co-doped tellurite-based glasses with composition of TeO 2-Zn O-Na2O are prepared by high-temperature melt-quenching technique.Effects of Ce2O3 content on the 1.53μm band fluorescence spectra and fluorescence lifetime of Er3+are measured and investigated.It is found that the tellurite glass containing Ce2O3 with molar concentration of 0.25%exhibits an increment of 13%in 1.53μm fluorescence intensity and an increment of 15%in the 4I13/2 level lifetime.The results indicate that the prepared tellurite-based glass with a suitable Er3+/Ce3+codoping concentration is an excellent gain medium applied for broadband Er3+-doped fiber amplifier(EDFA)pumped with a980 nm laser diode.     

LD抽运Nd3+:Ca3(VO4)2晶体实现1.06 μm脉冲激光输出

我们生长出了大尺寸的Ca3(VO4)2钒酸钙晶体并且探索以极化的条件,同时对于LD抽运Ca3(VO4)2激光进行了探索,实现了脉冲激光输出.     

钛宝石激光器抽运Cr4+,Yb3+:YAG晶体薄片获得1.03 μm自调Q激光输出

我们最近进行了用钛宝石激光器抽运Cr,Yb:YAG晶体的实验,获得了1.03 μm自调Q激光输出.实验所用的Cr,Yb:YAG晶体是本课题组用提拉法生长的,Cr和Yb的浓度分别为0.5 at.-%和10 at.-%.