提高稀土掺杂光波导放大器增益的技术进展

稀土掺杂光波导放大器(RDWA)是继光纤放大器(RDFA)之后的新一代稀土掺杂光放大器,其更适用于未来光放大器集成化、小型化的要求,并且在降低成本方面优势明显。提高RDWA性能通常从提高稀土离子发光效率和降低波导损耗两个方面进行探究,这就要求更加合适的掺杂材料和高性能的波导结构,以及尽可能低的传输损耗。总结了稀土掺杂玻璃基、聚合物基、硅基及低损耗材料基质光波导放大器的研究进展,最后展望了本领域的发展前景。     

Er3+/Yb3+共掺Al2O3光波导放大器的成分优化

利用980 nm泵浦光激发下Er3+/Yb3+共掺Al2O3光波导放大器的粒子数速率方程,研究了稀土离子掺杂浓度对Er3+/Yb3+共掺Al2O3光波导放大器光学增益的影响.在此模型中,充分考虑到受激吸收、受激发射、自发辐射、能量转移等过程,揭示了稀土离子掺杂浓度和光学增益之间的紧密关系.结果表明,适量Yb3+的共掺杂能够显著提高Al2O3光波导放大器的光学增益.光波导放大器中Er3+/Yb3+的最佳共掺杂浓度不是固定值,受到泵浦功率、光波导放大器长度等因素影响,揭示了各有关报道中最佳掺杂浓度结果不一致的原因.     

掺铒光波导放大器在机场通信中的应用及研究进展

掺铒光波导放大器(EDWA)在民航机场通信领域具有广阔的应用前景.综述了EDWA在机场通信领域的研究背景、结构特征、工作原理以及研究现状和研究意义等,分析了国内与国外的差距,指出了目前研究工作中急待解决的诸多问题.     

通讯窗口稀土(钕和铒)掺杂有源光波导材料的研究进展

稀土（钕和铒）掺杂有源光波导材料可应用在1.34μm和1.54μm两通讯窗口的光放大，综述了通讯窗口波段的稀土掺杂有源光波导材料的研究现状，阐述了不同基质材料的优缺点，提出了稀土有机配合物作为有源光波导激光物质的新的研究方向，并展望其发展前景。     

Er3+/Yb3+共掺Al2O3光波导放大器的成分优化

利用980nm泵浦光激发下Er3+/Yb3+共掺Al2O3光波导放大器的粒子数速率方程,研究了稀土离子掺杂浓度对Er3+/Yb3+共掺Al2O3光波导放大器光学增益的影响。在此模型中,充分考虑到受激吸收、受激发射、自发辐射、能量转移等过程,揭示了稀土离子掺杂浓度和光学增益之间的紧密关系。结果表明,适量Yb3+的共掺杂能够显著提高Al2O3光波导放大器的光学增益。光波导放大器中Er3+/Yb3+的最佳共掺杂浓度不是固定值,受到泵浦功率、光波导放大器长度等因素影响,揭示了各有关报道中最佳掺杂浓度结果不一致的原因。     

聚合物光波导端面磁流变抛光工艺(英文)

光波导端面的表面质量会严重影响光波导器件的光耦合封装性能,耦合封装前必须对波导器件端面进行抛光处理.目前聚合物光波导端面主要依靠传统研磨盘进行抛光处理,该工艺工序复杂、抛光效率低已成为制约聚合物波导器件应用的瓶颈.基于聚合物光波导材料优良的加工特性,通过对比实验提出了聚合物光波导的磁流变端面抛光工艺.采用5μm、0.5μm和1μm粒径的氧化铈抛光粉分别配制研磨盘抛光液及磁流变抛光液对3 mm×3 mm聚合物光波导端面进行抛光实验,发现磁流变加工对聚合物光波导端面进行一次2 m in光栅扫描抛光就具有比传统研磨盘约3 h精、粗抛光较好的端面质量.经过白光干涉仪测量,磁流变抛光后光波导端面表面粗糙度的均方根值达到了2.6 nm,传统端面抛光端面粗糙度均方根值为128.7 nm.通过自动对准耦合平台测试,结果显示通过磁流变端面抛光的光波导的插入损耗由抛光前的32.7 dB降低到了17.8 dB.磁流变抛光方法可以对聚合物光波导端面进行快速、高性能的抛光,在光波导应用领域具有非常广阔的应用前景.     

溶胶-凝胶法制备有机-无机杂化光波导材料研究进展

有机-无机杂化材料因同时具有有机功能基团和无机功能基团的结构特点而易于有机光活性物质和无机活性物质的掺杂已被人们广泛关注和大力研究.溶胶-凝胶法是制备有机-无机杂化光波导材料的主要方法.阐述了溶胶-凝胶法制备杂化材料的原理,比较了几种目前研究得较多的有机-无机杂化光波导材料体系,指出了各自的优缺点,介绍了杂化材料制备光波导器件的工艺流程,最后归纳了溶胶-凝胶法制备有机-无机杂化光波导材料过程中存在的问题.     

玻璃光波导研究进展

介绍了目前国际上主要玻璃光波导的研究热点。阐述了制备光波导的晶体材料、玻璃材料和高分子聚合物材料的优缺点。着重阐述了玻璃材料的研究进展,并简要介绍了采用硫卤玻璃制备非线性光波导的诱人前景。     

锥脊波导SOA光耦合机制的理论分析

针对半导体光放大器（SOA）与单模光纤的耦合问题，详细介绍了当前最新的锥脊光波导耦合技术，用光波电磁场干涉理论建立了锥脊光波导的传输模式方程，并根据光波的全反射理论，揭示了锥脊光波导等效折射率的渐变规律，从理论上分析了锥脊波导SOA的光耦合机制，理论分析与相关报道的实验结果吻合。     

低损耗离子交换玻璃基光波导制备与分析

考虑到离子交换和离子扩散工艺的特殊要求, 设计并熔制了适合于离子交换工艺的硅酸盐玻璃材料SiO₂-B₂O₃-Al₂O₃-R’O-R₂O（R’=Ca, Mg; R=Na, K）. 采用Ag⁺/Na⁺熔盐离子交换和电场辅助离子扩散工艺在这种玻璃材料基片上获得了掩埋式条形光波导. 光学显微镜和电子探针分析表明高折射率的Ag⁺扩散区位于玻璃基片表面以下约10μm处, 形成光波导的芯部. 光波导芯部尺寸约为8μm×8μm, 与单模光纤芯径尺寸相当, 保证了较低的光纤耦合损耗. 对光波导的测量结果得出：在波长为1.5μm处条形光波导的传输损耗约为0.1dB/cm, 与单模光纤的耦合损耗约为0.2~0.3dB. 条形光波导的传输损耗与材料本身的损耗接近, 表现出掩埋式光波导的低损耗特征. 分析表明, 经过进一步优化, 这种光波导制备技术可用于低损耗光波导器件的制作.     

Polymer‐Based Optical Waveguides: Materials,Processing, and Devices

Polymer optical waveguide devices will play a key role in several rapidly developing areas of broadband communications, such as optical networking, metropolitan/access communications, and computing systems due to their easier processibility and integration over inorganic counterparts. The combined advantages also makes them an ideal integration platform where foreign material systems such as YIG (yttrium iron garnet) and lithium niobate, and semiconductor devices such as lasers, detectors, amplifiers, and logic circuits can be inserted into an etched groove in a planar lightwave circuit to enable full amplifier modules or optical add/drop multiplexers on a single substrate. Moreover, the combination of flexibility and toughness in optical polymers makes it suitable for vertical integration to realize 3D and even all‐polymer integrated optics. In this review, a survey of suitable optical polymer systems, their processing techniques, and the integrated optical waveguide components and circuits derived from these materials is summarized. The first part is focused on discussing the characteristics of several important classes of optical polymers, such as their refractive index, optical loss, processibility/mechanical properties, and environmental performance. Then, the emphasis is placed on the discussion of several novel passive and active (electro‐optic and thermo‐optic) polymer systems and versatile processing techniques commonly used for fabricating component devices, such as photoresist‐based patterning, direct lithographic patterning, and soft lithography. At the end, a series of compelling polymer optical waveguide devices including optical interconnects, directional couplers, array waveguide grating (AWG) multi/demultiplexers, switches, tunable filters, variable optical attenuators (VOAs), and amplifiers are reviewed. Several integrated planar lightwave circuits, such as tunable optical add/drop multiplexers (OADMs), photonic crystal superprism waveguides, digital optical switches (DOSs) integrated with VOAs, traveling‐wave heterojunction phototransistors, and three‐dimensionally (3D) integrated optical devices are also highlighted.     

掺Er3+:Al2O3平面光波导的溶胶-凝胶制备

掺铒光波导主要用来制作光波导放大器。采用溶胶-凝胶法制备了透明、稳定的掺铒的铝硅酸盐玻璃溶胶;使用浸渍提拉法或旋转涂敷法,并通过放在乙醇蒸汽中干燥,可在玻璃表面得到均匀的凝胶膜;最后样品在一定温度下烧结;通过多次重复涂敷-烧结这一工艺流程可以形成厚的硅酸盐玻璃膜层并得到波导结构。使用显微镜研究了凝胶膜表面性质,通过棱镜耦合法测量了波导的有效折射率Nm,也测定了所制备波导的吸收光谱。溶胶-凝胶法在制作均匀性好、高掺铒浓度的铝硅酸盐玻璃光波导上具有优势。     

Design of photonic crystal-based all-optical AND gate using T-shaped waveguide

Abstract

We present a new configuration of all-optical AND gate based on two-dimensional photonic crystal composed of Si rods in air. Two AND gate structures with and without probe input are proposed. The proposed structures are designed with T-shaped waveguide without using nonlinear materials and optical amplifiers. The performance of the proposed AND gate structures is analyzed and simulated by plane-wave expansion and finite difference time domain methods. The AND gate without probe input needs only one T-shaped waveguide, whereas the AND gate with probe input needs two T-shaped waveguides. The former AND gate offers a bit rate of 6.26 Tbps with a contrast ratio of 5.74 dB, whereas the latter AND gate offers a bit rate of 3.58 Tbps whose contrast ratio is 9.66 dB. It can be expected that these small size T-shaped structures are suitable for large-scale integration and can potentially be used in on-chip photonic integrated circuits.     

Quantum amplifiers at microwave frequencies using Josephson junctions

Abstract

Josephson junctions are quantum mechanical devices with sinusoidal nonlinearity and their use as amplifiers of non-classical microwaves in cavities at low temperatures, is discussed. Self-pumped amplifiers as well as externally pumped three- and four-photon amplifiers are considered, and a quantum theory that describes their operation is developed. It is shown that the sinusoidal nonlinearity can be expanded into a series of terms, the first few of which are familiar from quantum optical amplifiers that use nonlinear optical materials, while the others are higher order corrections.     

Liquid phase epitaxy: A versatile technique for the development of miniature optical components in single crystal dielectric media

In this paper we will review the possibilities of liquid phase epitaxy (LPE) as a versatile technique for the development of new miniature optical components in single crystal dielectric media. These LPE layers can be used in active waveguide configuration as laser or amplifier sources or in transverse configuration as saturable absorber deposited on an active layer. So in the first part of this paper, we will present the LPE process by describing the growth conditions of rare earths doped YAG layers and by discussing the properties obtained in laser planar waveguides. In a second part, we will discuss some other applications, as amplifiers or saturable absorbers, using LPE layers. In the third and last part, we will present the interest of LPE for other materials, used as laser waveguides.     

Spectral noise analysis of single- and double-pass Er3+ - doped LiNbO3 waveguide amplifiers

Abstract

In this paper we report the derivation and evaluation of the spectral optical gain, spectral noise figure, amplified spontaneous emission photon number and signal-to-noise ratio in single- and double-pass configurations for an Er³⁺-doped LiNbO₃ waveguide amplifier pumped near 1484nm. The theoretical analysis was made using the small-gain approximation in the unsaturated regime. The simulations show the evolution of the above-mentioned parameters under various pumping regimes and waveguide lengths. The results obtained show how the model can be used for the design of Er³⁺-doped LiNbO₃ waveguide amplifiers.     

Near infrared photonic devices based on Er-doped GaN and InGaN

Er-doped III-nitride semiconductors have emerged as very attractive materials to achieve photonic devices with multiple functionalities for photonic integrated circuits (PICs). Optical sources and amplifiers based on these materials, particularly GaN and InGaN alloys, can operate at 1.54 μm and are expected to be temperature insensitive and have high signal gain with low noise. There is also the potential for these devices to be electrically pumped and to be integrated onto PICs, which is not possible with either Er-doped silica glasses or narrow bandgap semiconductors like InGaAsP. Here we present results on near infrared emitters and optical amplifiers based on Er-doped GaN/InGaN epilayers grown on different substrates by metal organic chemical vapor deposition (MOCVD). In particular, we report on chip-size current injected emitters and amplifiers fabricated by heterogeneously integrating Er-doped GaN/InGaN epilayers with UV nitride light-emitting diodes. The feasibility of developing electrically pumped optical amplifiers for PIC integration will also be discussed.     

硅基光电集成材料及器件的研究进展

以硅基光电集成回路为主线，综述了不同的硅基光波导材料的制备技术和硅基光波导的制作工艺及其对光传输损耗的影响。分析了硅基光波导与锗硅光探测器集成用两种不同的耦合方式，阐明了波导与探测器集成的机理及设计理论基础。归纳出硅基键合激光器的四种技术方案，指出其共同优点是克服材料异质外延引起的晶格失配和热膨胀非共容，对实现OEIC行之有效。     

Tight packaging of erbium-doped waveguide amplifiers

A numerical model for erbium-doped waveguide amplifiers (EDWAs) containing bent waveguides was developed. The model uses rate-propagation equations and takes into account bend-induced losses in the waveguide with a varying radius of curvature. It is applied to the design of tightly packed erbium-doped waveguide amplifiers under two constraints: minimization of the area required to obtain a predetermined gain and maximization of the gain available from a given area. Numerical calculations based on realistic waveguide parameters demonstrate the possibility of fabricating high-gain, small-size EDWAs. Simple design rules, based on geometric formulas and consideration of bend losses, are given and compared with the results of numerical calculations.