超宽带光纤放大器用的新型掺铋发光材料

最近,一种新型的掺铋发光材料引起了人们的关注。这种发光材料有长的荧光寿命(τ>200μs),在800nm激光激 发下发射波长在1200-1600nm区间的超宽带荧光(荧光半高宽FWHM>200nm),其发光性质与以往文献中报道的Bi3+或 Bi2+掺杂的发光材料的性质截然不同;光发射截面(σem)是光掺铒光纤放大器玻璃(EDFAG)的2-3倍,其σem×FWHM值是 EDFAG的10倍左右,σem×τ值是掺Ti3+蓝宝石的3倍左右。     

磷硅酸盐掺铋光纤实现O+E波段放大

由于数据流量需求的逐年增加,现有光纤放大器的传输带宽已很难应对光纤通信系统的容量危机,实现扩展波段的光放大被认为是一种解决容量危机的有效方案。不同基质的掺铋光纤的发光范围可以覆盖大部分的传输窗口,因此具有重要的研究意义和广阔的应用前景。报道了一种基于改进的化学气相沉积技术制备的磷硅酸盐掺铋光纤,并测试了其基本参数及放大性能。该掺铋光纤在1550 nm处的背景损耗为21 dB/km,在1240 nm处的吸收系数达0.58 dB/m,非饱和损耗占比为13.6%。通过搭建单级前向泵浦结构测试了该掺铋光纤的放大性能,当输入信号功率为-15 dBm时,采用泵浦功率为460 mW的1240 nm半导体激光器进行泵浦,将光纤长度优化至140 m,实现了O+E波段（1270～1480 nm）的净增益,并在1340 nm处得到了最大增益（21.2 dB）,其3 dB带宽约为55 nm(1310～1365 nm)。     

高吸收锗硅酸盐掺铋光纤及其增益性能研究

目前基于掺铒光纤放大器（EDFA）的光纤通信骨干网络仅能有效利用C+L波段（1524～1625 nm）。在E+S波段,锗硅酸盐掺铋光纤可进一步扩展放大器的增益带宽,具有重要研究价值,但其过长的使用长度严重制约了其应用。报道了一种高吸收锗硅酸盐掺铋光纤,其使用长度得到大大缩短,同时具有高增益。基于前向泵浦结构测试了掺铋光纤的增益性能,泵浦功率和波长分别为367 mW和1310 nm,输入信号总功率为-20 dBm。结果表明,50 m长的光纤在1414～1479 nm实现了大于20 dB的增益,65 m长的光纤的增益在1450 nm处达到最大（33 dB）,单位长度增益系数达0.51 dB/m。研究结果证明了锗硅酸盐掺铋光纤在WDM光纤通信网络中的实际应用潜力。     

用于U波段高效放大的高锗掺铋光纤

掺铋(Bi)光纤由于其超宽带近红外发光性能引起了广泛关注,然而实现U波段高效放大的高锗(Ge)掺铋光纤在国内依然尚未研制成功,这是因为在掺铋光纤中实现高掺锗是一项极具挑战的工艺难点,同时如何实现Bi向Ge相关铋活性中心高效转化也是一个难题。基于改进的化学气相沉积技术,制备了一种纤芯GeO₂摩尔分数约为42%的高锗掺铋光纤。其吸收测试结果显示,在1650 nm处出现明显的Ge相关铋活性中心的吸收峰。通过单级放大系统表征了其放大性能,在1670 nm处实现了26.3 dB的最高增益,增益效率达0.165 dB/mW。     

U波段放大用国产高增益掺铋高锗硅基光纤

<正>掺铋石英光纤在1100～1800 nm波段具有超宽带发光特性，在全波段光通信领域展现出重大的应用潜力。铋离子在近红外波段的光谱特性与玻璃成分密切相关，在含不同共掺元素的硅基玻璃中可形成以下铋活性中心（BAC）:BAC-Al、BAC-P、BAC-Si、BACGe。自2004年以来，国外研究机构在多波段宽带放大用掺铋光纤方面取得重大突破，如俄罗斯科学院光纤光学研究中心（FORC）和英国南安普敦大学。     

Er3+/Ce3+共掺铋锗酸盐玻璃及其光纤的制备和光谱性质

用高温熔融法制备了Er3+/Ce3+共掺铋锗酸盐(Bi2O3-GeO2-Ga2O3-Na2O)玻璃,研究分析了该玻璃中Er3+离子1.5μm波段荧光和上转换发光,Ce3+离子共掺引入的Er3+:4I11/2→Ce3+:2F5/2间能量传递能有效地抑制上转换发光并增强1.5μm波段荧光发射.同时,利用该组分玻璃拉制了包层直径为125 μm的铋锗酸盐玻璃掺Er3+光纤,1310 nm波长处光纤传输损耗为3.4 dB/m.通过对975 nm波长激励下光纤的放大自发辐射(ASE)测试表明,铋锗酸盐玻璃掺Er3+光纤可在1450～1650 nm波长范围获得宽带ASE光谱,因此是一种适用于宽带光纤放大器的增益介质.     

铋镓铝共掺的高浓度掺铒光纤及放大器

研制出了铋镓铝共掺的高浓度掺铒光纤,这种掺铒光纤在1 530 nm处的吸收系数达到了28.5 dB/m.利用这种铋镓铝共掺的高浓度掺铒光纤制成了C波段和L波段的掺铒光纤放大器(EDFA),测试这两种放大器的荧光谱和增益谱线.利用2.5 m的高浓度掺铒光纤制作的C波段EDFA就实现了高增益.利用10 m这种掺铒光纤制作的L波段放大器实现了有效的I波段放大.     

具有超宽带近红外发光的铋激活光子玻璃

在铋掺杂的各种玻璃体系中能够产生覆盖1.2～1.6μm区间的超宽近红外发光；并对此类发光材料的发光机理进行了初步探讨，指出铬铋共掺的锌铝硅玻璃中的宽带近红外发光源于铋而不是Cr^4＋离子。     

特大口径高功率脉冲氙灯的研制取得进展

上海光机所超宽带光放大材料研究小组对铋掺杂玻璃展开了系统的研究。在808nm半导体激光器的泵浦下，发现铋掺杂硅酸盐、锗酸盐、硼酸盐、磷酸盐等系统玻璃在室温下能产生横盖1．2-1．6μm区间的超宽带荧光，荧光寿命一般为几百微秒，荧光半高宽在200-400nm之间。该类发光材料极有望用做光通讯领域中超宽带光放大器以及超宽带可调谐激光器的增益介质，并首次提出了基于低价铋的发光机理。     

宽带铋基掺铒光纤放大器的增益箝制研究

应用于动态通信网络中的光放大器需要恒定的信号增益.为此,设计了一个基于环形激光腔结构的宽带铋基掺铒光纤放大器(Bi-EDFA),进行了宽带Bi-EDFA信号增益箝制特性的理论研究.结果表明:通过将放大器输出的一个前向放大自发辐射(ASE)噪声光反馈到输入端,可以实现对1.53 μm波段传输信号的增益箝制.环路损耗越小,...     

光电子技术及光电子器件的发展趋势

光纤通信和光盘技术是光电子技术中的重要领域。本文介绍了光纤通信技术的应用以及世界范围内光电子产业的市场分配及其增长情况。去年综合业务数字网(ISDN)系统投入商用标志着电信事业新纪元的开端。预计到本世纪末能利用数据、图象、视频和话音等多种通信方式的宽带B-ISDN系统将得到迅速发展。在光电子产业中占据重要地位的光盘技术亦具有广阔的应用前景。文中介绍了分布反馈(DFB)激光器、波长可调谐激光器、半导体激光放大器和面发射激光器等方面的最新研究结果。并以表格形式概述了某些其它发射器件和接收器件的发展水平。     

Compact solid-state waveguide lasers

Glass waveguide lasers will fill an important niche as optical sources in communication, RF photonics, and optical metrology. This is primarily because waveguide lasers benefit from compact size, low noise, relatively high output powers, long upper-state lifetimes, and simple integration with optical-fiber-based systems. Although we do not expect waveguide lasers and amplifiers to ever supplant fiber and semiconductor lasers and amplifiers in every possible communications application, waveguide lasers have a number of advantages over traditional lasers for these uses. Single-frequency waveguide lasers provide narrow linewidth and high output power in a compact, monolithic package. The narrow linewidth is an important advantage over standard semiconductor lasers, and the compact size makes single-frequency waveguide lasers better suited than fiber lasers or extended-cavity semiconductor lasers for many applications.     

信息光子学

评述了光子学在光学纤维、半导体激光器、光纤放大器、纤维光学无源元件、纤维光学检测设备、光纤孤子通讯和量子通讯中的应用。     

Amplification of spontaneous emission in erbium-doped single-modefibers

Amplification of spontaneous emission (ASE) in erbium-doped single-mode fiber amplifiers operating at λ=1.53 μm is studied theoretically and experimentally. The ASE noise spectra obtained from the theory are found to be in excellent quantitative agreement with the experimental data. The observed changes in ASE spectral shapes under different population inversion conditions are also explained. The model may be used to evaluate the performance of erbium-doped fiber lasers as well as to assess the noise characteristics of erbium-doped fiber amplifiers as applied to wavelength-division multiplexing optical communications     

Mode-locked erbium-doped fiber lasers as source for optical sensor networks over C and L bands

The performance of mode-locked erbium-doped fiber lasers in optical sensor networks is analyzed and compared with the results obtained by using commercial erbium-doped fiber amplifiers as source. Passive mode-locked lasers developed are based on nonlinear polarization rotation and they have been built using the same erbium-doped fiber amplifiers. To simulate a real sensor network, a tree structure with four fiber Bragg gratings was built employing 50/50 couplers. The mode-locked laser developed offers a reasonably good behavior at a very wide spectral range (83 nm, approximately) over C and L bands. The signal to noise ratio and the peak power are greatly improved with regard to the values obtained employing commercial amplifiers as source.     

Optical fibers and amplifiers for WDM systems

The development of optical-fiber amplifiers allowed a dramatic increase in the capacity of optical transmission systems while reducing system costs. Capacity increases are possible because the high output powers afforded by optical-fiber amplifiers support higher bit rates, while their broad bandwidth and slow gain dynamics allow multichannel operation. This benefit comes at the expense of having to manage signal-to-noise ratio degradations due to the accumulation of amplifier noise and dispersion distortions accumulated over the total system link. Furthermore, nonlinear optical effects become significant with the use of high power signals over long lengths of fiber, causing cross talk among the different channels and increasing signal distortions. To fully exploit the potential capacity of wavelength division multiplexing systems, the optical characteristics of the fibers and optical-fiber amplifiers must be optimized. The optical amplifiers should have low noise and flat gain, which can be achieved by using 980-nm pump lasers, optimized fiber glass composition, and gain-flattening filters. The optical fibers should have a small nonzero dispersion and large effective area. Both features can be achieved by optimizing the fiber index profile. This paper summarizes the state of the art in these components and points to directions for future exploration     

An overview of optical device research in China

An overview of research activities in China on the following optical communications devices is presented: quantum-well semiconductor lasers; distributed feedback laser diodes; wideband, tunable, narrow-linewidth, external-cavity laser diodes, semiconductor and doped-fiber amplifiers; laser-diode-pumped solid state and single-crystal fiber lasers; doped fiber ring lasers, optical modulators; switches; bistable devices; experimental wavelength-division-multiplexed (WDM) systems; and time-division photonic switching systems. The most important of these technologies are highlighted with respect to demonstrated achievements in China. The potential uses of these technologies in future telecommunications systems are discussed     

Fiber amps and lasers get down to earth

Practical optical fiber devices, particularly erbium-doped fiber amplifiers (EDFAs), are poised to tap the tremendous bandwidth of optical fibers in next-generation lightwave transmission systems, while enhancing network flexibility and reliability. Optical fiber amplifiers have come a long way since the first demonstration of a neodymium-doped type by Snitzer and Koester in 1964. It was not until the mid-1980s, however, that researchers began to revitalize and extend the field of rare-earth doped fiber devices by combining the technologies of low-loss silica optical fibers, rare-earth doped lasers, and semiconductor pump sources. Later this year, they will be practically applied in a big way     

Advances in Raman fibers

Raman fiber lasers and amplifiers will play an increasing role in future optical fiber communication (OFC) systems. Recent progress in the development of special Raman fibers is described. We particularly focus on high /spl Delta/n germanosilicate and phosphosilicate fibers.     

Lightwave applications of fiber Bragg gratings

Fiber Bragg gratings (FBGs) have emerged as important components in a variety of lightwave applications. Their unique filtering properties and versatility as in-fiber devices is illustrated by their use in wavelength-stabilized lasers, fiber lasers, remotely pump amplifiers. Raman amplifiers, phase conjugators, wavelength converters, passive optical networks, wavelength division multiplexers (WDMs) demultiplexers, add/drop multiplexers, dispersion compensators, and gain equalizers