新一代城域网解决方案

新一代SDH／SONET多业务传送技术和以DWDM和光交叉连接为主的光技术为运营商建设新一代城域网提供了良好的解决方案。本主要介绍了城域网的光传送技术的特点和富士通公司提供的最新全面解决方案。     

7-羟基喹啉二甲基亚砜溶液的光开关效应

研究了7羟基喹啉（7HQ）在二甲基亚砜（DMS）溶液中的全光光开关效应和激发态质子转移（ES-PT）效应。7HQ在与它能形成分子间氖键的溶剂中，在紫外光的激发下会发牛ESPT效应，使分子的构型发生变化，引起折射率也发生变化，是一种性能优良的全光光开关工作介质。DMS与7HQ不能形成分子间氢键，故7-HQ在DMS溶液中不能发生ESPT，不具有全光光开关效应。但实验发现，7-HQ的DMS溶液经强紫外光照射一段时间后出现了很强的光开关现象。比较了经强紫外光照射前后7-HQ的DMS溶液的吸收光谱和荧光光谱，报道了这一新现象并探讨了其产生的机理。     

Loss stability assurance against hydrogen for submarine opticalfiber cable

Hydrogen generation resulting from electrochemical reactions between cable metals and condensed water or moisture permeated through the cable jacket was studied. It was found that hydrogen generation increases exponentially as time elapses and tends to saturation after about one month. Partial pressure distribution along the cable of hydrogen generated in the immersed range of a damaged cable was analyzed by means of the diffusion equation and the optical loss increase was estimated. It was shown that a water-blocking resin effectively prevents water penetration and hydrogen diffusion along the cable     

Influence of Hydrogen on Optical Fiber Loss in Submarine Cables

Characteristics of the loss increase in optical fibers due to hydrogen permeation are described, and it is shown that the loss increase due to OH formation in GeO2-doped single-mode fibers is thought to be small compared to the loss increase due to the vibration of hydrogen molecules even in 20 years. Furthermore, the hydrogen generation due to electrochemical reaction in the optical cables is described. Finally, the countermeasure against the problem is discussed.     

太赫兹时域光谱仪在陶瓷涂层及低压气体检测中的应用

太赫兹时域光谱仪(Terahertz Time-Domain Spectrometer,THz--TDS)在光谱学、材料表征、安检、通信等众多领域具有广阔的应用前景。介绍了一种稳定的波长为1560 nm的光纤短脉冲激光器以及一种基于该激光器的THz--TDS系统。然后用该系统对几种陶瓷基复合材料(Ceramic Matrix Composites,CMC)进行了无损检测。特别是在对热障涂层(Thermal Barrier Coating,TBC)的厚度进行检测时,实现了微米量级的精度。相比于传统方法,太赫兹波对CMC具有较强的穿透性并且应用灵活,因此提供了更好的解决方案。最后使用太赫兹异步光学采样系统(Terahertz Asynchronous Optical Sampling,THz--ASOPS)对低压水蒸气进行了高分辨率光谱分析。结果表明,光谱分辨率达到10 MHz,比传统的THz--TDS提高了100倍以上。     

Organic Phenolic Configurationally Locked Polyene Single Crystals for Electro‐optic and Terahertz Wave Applications

We investigate a configurationally locked polyene (CLP) crystal 2‐(3‐(4‐hydroxystyryl)‐5,5‐dimethylcyclohex‐2‐enylidene)malononitrile (OH1) containing a phenolic electron donor, which also acts as a hydrogen bond donor. The OH1 crystals with orthorhombic space group Pna2₁ (point group mm2) exhibit large second‐order nonlinear optical figures of merit, high thermal stability and very favorable crystal growth characteristics. Higher solubility in methanol and a larger temperature difference between the melting temperature and the decomposition temperature of OH1 compared to analogous CLP crystals, are of advantage for solution and melt crystal growth, respectively. Acentric bulk OH1 crystals of large sizes with side lengths of up to 1 cm with excellent optical quality have been successfully grown from methanol solution. The microscopic and macroscopic nonlinearities of the OH1 crystals are investigated theoretically and experimentally. The OH1 crystals exhibit a large macroscopic nonlinearity with four times larger powder second harmonic generation efficiency than that of analogous CLP crystals containing dimethylamino electron donor. A very high potential of OH1 crystals for broadband THz wave emitters in the full frequency range of 0.1–3 THz by optical rectification of 160 fs pulses has been demonstrated.     

Material removal and particulate generation during abrasion of copper films using a fixed abrasive pad

Minimization of particulates levels during the chemical-mechanical planarization (CMP) process as well as in the waste streams is possible through the use of a fixed abrasive pad (FAP). The abrasion of electrodeposited copper films using an alumina-based FAP was studied in hydrogen peroxide and hydroxylamine-based chemistries. The removal rate of copper in hydrogen peroxide solutions was much lower than that in hydroxylamine-based solutions in the pH range of 3 to 9. The addition of citrate to peroxide solution enhances the removal rate of copper to a level that is comparable to removal rates in hydroxylamine-based solutions. Abrasion in a hydrogen peroxide solution resulted in the formation of copper and aluminum-based particulates in the solution. The addition of citrate to peroxide solutions reduced the generation of copper-based particulates that were generated in solution. In hydroxylamine-based solutions, particulate generation was minimal.     

Excited state proton transfer effect of 7-hydroxyquinoline in dimethyl sulfoxide solvent

Excitedstateprotontransfer(ESPT)effectoforganicmoleculeisafundamentalreactionofphotochemistry,anditexistswidelyinmanychemicalandbiological processes.Ithasbeenstudiedprofoundlybychemistsformanyyears[14].Moreover,theorganicmoleculewith ESPTeffectisalsoakind…     

Nonlinear optical response of planar and spherical CdSe nanocrystals

The nonlinear optical response of a colloidal solution of planar CdSe semiconductor nanocrystals (nanoplatelets) is studied for the first time. The nonlinear optical response of these nanoparticles is compared to that of spherical CdSe nanocrystals (quantum dots). The photoinduced nonlinearity is attributed to the optical generation of long-lived charge carriers in the nanoobjects under study. It is shown that, upon the exposure of a cell with the solution of nanoparticles to focused continuous-wave (cw) laser radiation with a wavelength of 473 nm, the nonlinear optical responses of CdSe nanoplatelets and quantum dots are somewhat different at identical optical densities at the above-indicated wavelength. The differences are supposedly associated with a higher diffusion rate of spherical nanoparticles in the solution because of their smaller size compared to that of nanoplatelets.     

Ultrasensitive Plasmonic Response of Bimetallic Au/Pd Nanostructures to Hydrogen

Hydrogen detection is crucial for the safety of all hydrogen‐related applications. Compared to electrical hydrogen sensors, which usually suffer from possible electric sparks, optical hydrogen sensors offer advantages of remote and contact‐free readout and therefore the avoidance of spark generation. Herein, bimetallic Au/Pd nanostructure monolayers that exhibit ultrasensitive plasmonic response to hydrogen are reported. Bimetallic Au/Pd nanostructures with continuous and discontinuous Pd shells are prepared. The plasmonic response to hydrogen is monitored by measuring the extinction spectra of the ensemble Au/Pd nanostructures deposited on glass slides. Introduction of hydrogen induces red plasmon shifts, which become larger for the nanostructures with thicker Pd shells. For the nanostructures with continuous Pd shell, the plasmon shift can reach 56 nm at the hydrogen volume concentration below the explosion limit. The plasmon resonance wavelength displays an excellent linear dependence on the hydrogen volume concentration below 1%. The detection limit in the experiments reaches 0.2%. The nanostructures with discontinuous Pd shell show smaller plasmon shifts than those with continuous Pd shell. The extinction measurements on the ensemble nanostructures supported on transparent substrates and the unprecedentedly large plasmon shifts and sensitivity make the results very promising for the development of practical optical hydrogen sensors.     

Optical quenching and energy extraction involving metastable and dissociative states in hydrogen

Optical quenching of metastable molecular species and the generation of tunable broad-band stimulated emission in the UV is considered for molecular hydrogen. A detailed theoretical analysis is summarized and a Study of the optical energy extraction process, using off-resonant optical pumping from the metastable statec^{3}Pi_{u}to the dissociative continuum stateb^{3}Sigma+_{u}, is presented. Earlier experimental work is discussed, and numerical results for the case of off-resonant pumping are presented.     

Photocurable 3D Printing of High Toughness and Self-Healing Hydrogels for Customized Wearable Flexible Sensors

Currently, most customized hydrogels can only be processed via extrusion-based 3D printing techniques, which is limited by printing efficiency and resolution. Here, a simple strategy for the rapid fabrication of customized hydrogels using a photocurable 3D printing technique is presented. This technique has been rarely used because the presence of water increases the molecular distance between the polymer chains and reduces the monomer polymerization rate, resulting in the failure of rapid solid-liquid separation during printing. Although adding cross-linkers to printing inks can effectively accelerate 3D cross-linked network formation, chemical cross-linking may result in reduced toughness and self-healing ability of the hydrogel. Therefore, an interpenetrated-network hydrogel based on non-covalent interactions is designed to form physical cross-links, affording fast solid-liquid separation. Poly(acrylic acid (AA)-N-vinyl-2-pyrrolidone (NVP)) and carboxymethyl cellulose (CMC) are cross-linked via Zn²⁺-ligand coordination and hydrogen bonding; the resulting mixed AA-NVP/CMC solution is used as the printing ink. The printed poly(AA-NVP/CMC) hydrogel exhibited high tensile toughness (3.38 MJ m⁻³) and superior self-healing ability (healed stress: 81%; healed strain: 91%). Some objects like manipulator are successfully customized by photocurable 3D printing using hydrogels with high toughness and complex structures. This high-performance hydrogel has great potential for application in flexible wearable sensors.     

吖啶酮衍生物粉末微晶的二次谐波测量

建立了有机物粉末二次谐波(SHG)的测量系统。测定了N-烃基口丫啶酮衍生物粉末的SHG,并以溶剂变色法测定了一些口丫啶酮衍生物的分子超极化率与分子基态偶极矩的复合量(βCTμg).从分子结构特征与分子折射率等方面对其所表现出的非线性光学性质进行了分析。具有“Λ”型多极结构、分子间氢键、支化烷基和甲基的口丫啶酮衍生物,粉末SHG较强;βCTμg与SHG相对强度近似线性关系;分子折射率与SHG不满足Kurtz-Pery关系。     

Terahertz Phonon Mode Engineering of Highly Efficient Organic Terahertz Generators

For terahertz (THz) wave generators based on organic electrooptic crystals, their intrinsic phonon modes are playing an essential role in THz generation characteristics. Here, this study proposes an effective design strategy for THz phonon mode engineering of organic electrooptic salt crystals for efficient optical‐to‐THz frequency conversion. To reduce phonon‐mode intensity, strongly electronegative trifluoromethyl group acting as strong hydrogen‐bond acceptor is incorporated into molecular anions. New 2‐(4‐hydroxy‐3‐methoxystyryl)‐1‐methylquinolinium 4‐(trifluoromethyl)benzenesulfonate (HMQ‐4TFS) crystals exhibit a relatively small absorption coefficient in the THz spectral range between 0.5 and 4 THz, which is attributed to suppressed molecular vibrations due to strong hydrogen bonds involving the 4TFS anion. In addition, HMQ‐4TFS crystals possess a very large macroscopic optical nonlinearity, comparable (or even higher) to benchmark stilbazolium crystals. Based on the low‐intensity THz phonon modes and the large optical nonlinearity, a 0.37 mm thick HMQ‐4TFS crystal pumped with 150 fs infrared laser pulses facilitates very efficient THz wave generation by optical rectification, delivering 23 times higher peak‐to‐peak THz electric field than the widely used standard inorganic ZnTe crystal (1.0 mm thick) and a broader spectral bandwidth. Therefore, strongly electronegative groups introduced into molecular salt electrooptic crystals provide a very promising design strategy of THz phonon mode engineering for developing intense broadband THz sources.     

Irradiation Effect on Second Harmonic Generation of Dyes Doped KDP Crystals

Most irradiation studies in the hydrogen bonded ferroelectrics have been concentrated on the transient defects induced by ionising radiation,such as ultraviolet(UV) light,where the defects are closely related to the optical properties.But heavy ion beam irradiation effects have rarely been studied.The structural,optical,and non-linear optical properties of the doped crystals were analyzed with the characterization studies,such as powder XRD,UV-Visible and second harmonic generation(SHG) measurements,respect...     

Ring–mesh topology design in a SONET–WDM network

This article deals with a ring–mesh network design problem arising from the deployment of an optical transport network. The problem seeks to partition the set of demand pairs to a number of rings and a mesh cluster, and to determine the location of the optical cross-connect system (OXC), while minimizing the total cost of optical add-drop multiplexers (OADMs), OXCs, and fiber links. We formulate this problem as a zero-one integer programming problem. In strengthening the formulation, we develop some valid inequalities for the zero-one quadratic (knapsack) polytope and a column generation formulation that eliminates the symmetry of ring configurations. Also, we prescribe an effective tabu search procedure for finding a good quality feasible solution, which is also used as a starting column for the column generation procedure. Computational results show that the proposed solution procedure provides tight lower and upper bounds within a reasonable time bound.     

太赫兹技术在陶瓷基复合材料缺陷无损检测中的应用

太赫兹时域光谱技术（THz-TDS）是一种通过宽频带太赫兹脉冲携带介质信息,从而完成对样品内部信息提取的无损检测技术。目前,这种技术大多应用于安全监测,外形成像等定性分析领域。将该应用广泛的陶瓷基复合材料做为检测样品,通过建立单点厚度检测模型和光学参数的提取,将该技术用于密度分布检测和孔洞缺陷尺寸检测,进行定量测量。设计并进行了验证实验,对标准材料及缺陷进行了探索性的测量及评价。实验获取了较为理想的时频光谱分析结果及成像结果,显示出了THz-TDS在材料的定量无损检测和探究材料特征方面具有揭示作用。     

Chirped RF Pulse Generation Based on Optical Spectral Shaping and Wavelength-to-Time Mapping Using a Nonlinearly Chirped Fiber Bragg Grating

Chirped radio-frequency (RF) pulse generation based on optical spectral shaping and nonlinear wavelength-to-time mapping in a nonlinearly chirped fiber Bragg grating (NLCFBG) is investigated. In the proposed approach, the spectrum of a femtosecond pulse generated by a mode-locked fiber laser is shaped by an optical filter that has a sinusoidal frequency response. The spectrum-shaped optical pulse is sent to the NLCFBG, to implement nonlinear wavelength-to-time mapping. A chirped electrical pulse with the central frequency and chirp rate determined respectively by the first- and second-order dispersions of the NLCFBG is then obtained at the output of a high-speed photodetector. An approximate model that describes the chirped RF pulse generation is derived, which is verified by numerical simulations. Chirped pulse generation with a pulse compression ratio as high as 450 is demonstrated. The key device in the chirped RF pulse generation system is the NLCFBG, which is investigated in detail with an emphasis on the influence of its group delay ripples on the performance of the pulse generation system. Techniques to design and fabricate the NLCFBG are also discussed. The proposed approach provides a potential solution for the generation of chirped RF pulse with a high central frequency and large chirp rate for applications in pulse compression radar systems.     

面向超100G系统的可变带宽ROADM及控制平面技术

研究了基于ROADM和灵活栅格技术的结合实现超100G光线路上的灵活封装和智能调度的解决方案。重点分析了如何通过控制平面的不同模块来实现更加高效支持灵活栅格的ROADM与整个超100G系统的协同统一工作,打造新一代智能弹性高速光网络的架构。