共查询到20条相似文献,搜索用时 120 毫秒
1.
《中国激光》2021,(7)
铒镱(Er~(3+)/Yb~(3+))共掺光纤是实现波长为1.5μm激光的重要增益介质之一。但是石英基Er~(3+)/Yb~(3+)共掺光纤很容易产生波长为1μm的放大的自发辐射(ASE)光,不仅降低1.5μm激光的泵浦转换效率,而且是限制1.5μm激光功率提升的"瓶颈"。研究结果表明,提升纤芯磷的掺杂量,能够增大纤芯基质的最大声子能量,有利于抑制Yb~(3+)的ASE光和Er~(3+)→Yb~(3+)的反向能量传递,从而提高Er~(3+)/Yb~(3+)共掺光纤的泵浦转换效率。通过改良的化学气相沉积制备工艺可以减少磷元素在高温条件下的挥发,从而成功制备出高掺磷的10/130μm双包层Er~(3+)/Yb~(3+)共掺光纤。测试光纤后向的1μm ASE光谱随泵浦功率的变化,并且搭建两级激光测试平台,测得Er~(3+)/Yb~(3+)共掺光纤激光的斜率效率为35.5%。 相似文献
2.
3.
4.
5.
6.
7.
8.
本文对1987年国外出现的光纤放大器研究进行评述,比较了半导体光放大器、光纤受激喇曼散射和受激布渊里散射的光放大及掺Er~(3+)光纤放大器的行为和特点。对Er~(3+)光纤放大器的实验研究及 相似文献
9.
10.
11.
应用线性组合算符和微扰法研究了电子自旋对SiC半导体性质的影响。基态能量E0^+(对应于电子自旋量子数为正)和E0^-(对应于电子自旋量子数为负)都随磁场增加而线性减少:在0T时,E0^+和E0^-都为-76.24meV;在25T时,E0^+和E0^-分别为-68.50meV和71.39meV。自旋能量与E0^+和E0^-之比P0^+和P0^-都随磁场增加而快速增加:在0T时,P0^+和P0^-都为0;在20T时,P0^+为0.627;在25T时,P0^-为0.453。自旋能量与Landau基态能量之比P2始终为0.23。自旋能量与自能和声子之间相互作用能量之比P1和P3都随磁场增加而线性增加:在0T时,P1和P3都为0;在5T时,P3为0.628;在40T时,P1为0.306。这些数据和结果有助于设计和研制自旋场效应晶体管、自旋发光二极管和自旋共振隧道器件等。 相似文献
12.
提出了有机掺杂电致磷光器件中主体(TPD)与客体(Ir(ppy)3)间的能量转移几率表达式,并对能量转移过程进行了讨论.结果表明:(1)三态激子能量转移率(KHG,KGH)随主客体分子间距离R指数增加,KHG随客体分子间距离RGG增加有一个快的减少,且KHG/KGH随R或RGG减少而增加;(2)当R为0.8~1.2nm时,能量转移几率接近线性降低,而当R<1.1nm时,RGG的变化能够被忽略,对于1.1nm<R<1.2nm的情况,RGG(<1.6nm)对η起着越来越重要的作用;(3)当Forster能量转移率增加或Gibb's能减小时,η将会增加. 相似文献
13.
The design of energy‐efficient underwater wireless sensor networks (UWSNs) poses many challenges due to the intrinsic properties of propagation medium and limited battery power of sensor nodes. This paper proposes the concept of optimal clustering for three‐dimensional (3D) UWSNs leveraging compressive sensing (CS) and principal component analysis (PCA) technique of data compression. Optimal clustering reduces the energy consumption by selecting the optimal number of clusters whereas CS and PCA compression techniques reduce the energy consumption by considering a lesser number of samples and reduce the data redundancy at cluster heads (CHs) level, respectively. Moreover, three communication techniques like acoustic, electromagnetic (EM), and free‐space optical (FSO) wave are considered for communication in 3D UWSNs. We compared the energy efficiency for all three communication techniques by examining the three base station (BS) positions at the center, at the corner, and at the lateral midpoint of the 3D sensing area. Moreover, performance parameters (network lifetime, throughput, packet drop rate, and latency) are also evaluated for 3D UWSNs. It is observed that PCA outperforms the CS technique. The proposed technique is suitable for long‐term and densely deployed 3D UWSNs, in which saving energy is of crucial importance. 相似文献
14.
基于密度泛函理论的第一性原理方法,在广义梯度近似下,研究了(5,0)和(5,5)硅纳米管结构和电子性质。计算结果表明:(5,0)管硅原子相邻键长波动范围为0.068 nm,大于(5,5)管的0.006 nm;通过对(5,0)管的分波态密度进行分析发现,其3s电子和2p电子能量分布在-13~3 eV,但2p电子集中分布在能量较高的-6~3 eV,出现了明显的sp3轨道杂化。同时对(5,0)和(5,5)硅纳米管最高占据轨道和最低未占据轨道的能隙进行了分析,发现两种管导电性能与结构的手性相关,锯齿型(5,0)管能带交叠具有明显的金属性,而扶手型(5,5)管能隙为0.151 eV是半导体纳米管。 相似文献
15.
Jayraj V. Vaghasiya Carmen C. Mayorga-Martinez Martin Pumera 《Advanced functional materials》2021,31(48):2106990
Three-dimensional (3D) printing technology has a pronounced impact on building construction and energy storage devices. Here, the concept of integrating 3D-printed electrochemical devices into insulation voids in construction bricks is demonstrated in order to create electrochemical energy storage as an integral part of home building. The low-cost 3D-printed supercapacitor (SC) electrodes are created using graphene/polylactic acid (PLA) filament in any desired shape such as 3D cylindrical- (3Dcy), disk- (3Ddc), and 3D rectangular- (3Drc) shaped electrodes. To obtain excellent capacitive performance, a Ti3C2@polypyrrole (PPy) hybrid is uniformly electroplated on the surface of 3D-printed electrodes. These Ti3C2@PPy-coated 3D-printed electrodes exhibit outstanding electrical conductivity, capacitive performance, cycle life, and power density. The bricks themselves act as an excellent scaffold for electrochemical energy devices as they are electrically insulating, fire-resistant, and contain substantial unused thermal insulation voids. A 3Drc Ti3C2@PPy SC is integrated into a real brick to showcase a smart house energy storage system that allows to reserve power in the bricks and use it as a power backup source in the event of a power outage in the elevator. This concept provides a platform for future truly smart buildings built from added value “smart brick” energy storage systems. 相似文献
16.
17.
Tm:Yb:KY(WO4)2晶体蓝光上转换 总被引:2,自引:2,他引:2
利用顶部籽晶提拉(TSSG)法生长了Yb3 ,Tm3 共掺KY(WO4)2晶体,在室温下测量了290~1200nm内晶体的吸收光谱。根据上转换模型研究了晶体中Yb3 向Tm3 进行能量传递的机制并对晶体中跃迁能级进行了指认,建立了简单的速率方程。计算得出Yb3 离子向Tm3 离子的能量传递效率接近于1。在974nm激光二极管抽运下观察到Tm3 离子的波长为476nm蓝色上转换发光。利用Fadenbrug-luechtbauer方法计算了1G4到3H6能级跃迁的发射截面积,其最大发射截面积约为1.51×10-20cm2。 相似文献
18.
The energy relaxation associated with acoustic phonons has been investigated in a series of modulation doped GaAs/AlGaAs single and multiple quantum wells grown by molecular beam epitaxy, using the hot electron Shubnikov — de Haas effect. The power loss is shown to be proportional to (Te2 − TL2) for electron temperatures 2.2K < Te < 8K and proportional to (Te3 − TL3) for 8K < Te < 20K. The energy loss rates due to acoustic phonon scattering via both deformation potential coupling and piezoelectric coupling have been calculated. The total energy loss rate as a function of electron temperature is compared with the experimental results. Good agreement is obtained for 2.2K < Te < 8K. Above 8K the energy loss rate is seen to rise above the predicted values, indicating the onset of an extra energy relaxation mechanism. The application of a high electric field (E = 3kV/cm) at low lattice temperatures is shown to induce persistent parallel conduction and a subsequent reduction of the low field well mobility. 相似文献
19.
Jingen Wu Huaduo Shi Tianlong Zhao Yang Yu Shuxiang Dong 《Advanced functional materials》2016,26(39):7186-7194
Conventionally, effective mechanical vibration energy harvesting is based on (Pb,Zr)TiO3 (PZT) ceramics, poly(vinylidene fluoride) (PVDF) polymers or PVDF/PZT or other piezoelectric composite materials, and their working temperature is normally limited to room temperature (R‐T) or below 150 °C. Here, bismuth scandium lead titanate (BiScO3‐PbTiO3, abbreviated as BSPT) ceramic is reported which has a high Curie temperature point around 450 °C and its application for high‐temperature (H‐T) vibration energy harvesting. Experimental results show that it exhibits an excellent H‐T piezoelectricity, converting mechanical vibration energy into electric power effectively in a wide temperature range from R‐T till 250 °C. This research shows the BSPT piezoelectric energy harvester having the potential application for self‐power source of wireless sensor network system in high temperature circumstance. 相似文献
20.
A Clear,Strong, and Thermally Insulated Transparent Wood for Energy Efficient Windows 总被引:2,自引:0,他引:2
Ruiyu Mi Tian Li Daniel Dalgo Chaoji Chen Yudi Kuang Shuaiming He Xinpeng Zhao Weiqi Xie Wentao Gan Junyong Zhu Jelena Srebric Ronggui Yang Liangbing Hu 《Advanced functional materials》2020,30(1)
The energy used for regulating building temperatures accounts for 14% of the primary energy consumed in the U.S. One‐quarter of this energy is leaked through inefficient glass windows in cold weather. The development of transparent composites could potentially provide affordable window materials with enhanced energy efficiency. Transparent wood as a promising material has presented desirable performances in thermal and light management. In this work, the performance of transparent wood is optimized toward an energy efficient window material that possesses the following attributes: 1) high optical transmittance (≈91%), comparable to that of glass; 2) high clarity with low haze (≈15%); 3) high toughness (3.03 MJ m?3) that is 3 orders of magnitude higher than standard glass (0.003 MJ m?3); 4) low thermal conductivity (0.19 W m?1 K?1) that is more than 5 times lower than that of glass. Additionally, the transparent wood is a sustainable material, with low carbon emissions and scaling capabilities due to its compatibility with industry‐adopted rotary cutting methods. The scalable, high clarity, transparent wood demonstrated in current work can potentially be employed as energy efficient and sustainable windows for significant environmental and economic benefits. 相似文献