40Gbps NRZ在基于宽带CFBG色散补偿的G.652光纤中无电中继传输500km

在基于宽带CFBG色散补偿的G.652光纤中,40Gbps NRZ码无电中继传输500km,在误码率BER=10(-10)下的功率代价约为2.2dB,积累1h的误码率为7.3×10(-12).传输系统中采用的CFBG的3dB带宽约为1.2nm,中心波长处时延纹波小于25ps,反射谱纹波小于2dB,差分群时延小于1ps....     

N-二茂铁甲基丁胺的合成

以二茂铁甲醛和正丁胺为原料,经缩合、还原反应制得N-二茂铁甲基丁胺。采用连续操作的方法,用正交实验确定了反应的最佳条件:二茂铁甲醛10 mmol,n(FcCHO)∶n(n-C4H9NH2)∶n(KBH4)=1.0∶1.4∶1.4;于(65±2)℃缩合反应6 h;于(55±2)℃还原反应8 h,产率可达77.8%。在最佳条件下实验规模放大50倍,收率达80.5%,纯度达99.5%。     

Numerical simulation of the thermal non-equilibrium flow-field characteristics of a hypersonic Apollo-like vehicle

In order to investigate the relationship between the flow-field parameters outside the vehicle and the altitude, this paper takes the Atmospheric Reentry Demonstrator (ARD) with an angle of attack of -20° as the research object and adopts a two-temperature model coupled with the shear-stress transport k-ω turbulence model to focus on the variation of flow-field parameters including flow-field pressure, Mach number and temperature with the reentry altitude. It is found that the flow-field high-pressure region and low-Mach region both appear in the shock layer near the head of the ARD, while the maximum pressure of the surface appears on the windward side of the ARD's head with a toroidal distribution, and the numerical magnitude is inversely proportional to the radius of the torus. With fluid through the shoulder of the ARD flow expansion plays a dominant role, the airflow velocity increases, the Mach number of the windward side of the rear cone increases and the flow-field pressure and surface pressure rapidly decrease. When the fluid passes through the shock layer, the translational-rotation temperature will increase before the vibration-electron temperature, there is a thermal non-equilibrium effect and the two temperatures will rapidly decrease again when approaching the surface of the ARD due to the existence of temperature gradient. At the same time, both the windward side of the shoulder and the back cover of the ARD suffer from a large thermal load and require thermal protection.     

Determination of Ionization Coefficient of Atmospheric Helium in Dielectric Barrier Discharge

A weakly luminous layer close to the anode is observed at time far ahead of the current pulse in dielectric barrier discharge of helium at atmospheric pressure and it is considered as the result of a very weak Townsend discharge. Based on the assumption that the space charge produced by this Townsend discharge is too small to distort the uniform electric field in the gas gap, the electrons have more or less the same energy over the entire gap and the spatial distribution of the discharge light is proportional to the distribution of electron density. This light distribution is obtained by processing side-view photograph of discharge gap using an intensified charge coupled device camera with an exposure time of 20ns. By fitting a theoretically derived formula with the measured curve of light distribution, the Townsend electron ionization coefficient α is determined to be 31 cm^-1 at E/p = 3.6 V·cm^-1·Torr^-1, which is much higher than that obtained by solving the Boltzmann equation of pure helium. It is believed that penning ionization of helium metastables with impurity of nitrogen molecules makes great contribution to the experimentally determined α value. The contribution of this penning ionization to α is roughly estimated.     

A Simple Loop for Simultaneous OTDM Demultiplexing and Clock Recovery

A simple and stable loop consisting of a pair of concatenated electroabsorption modulators （EAMs） and 10 GHz clock recovery module is presented and demonstrated experimentally for simultaneous demultiplexing and clock recovery for OTDM networks. The 10 Gb/s demultiplexed signal and 10 GHz recovered clock are successfully implemented from 80 Gbit/s and 160 Gbit/s OTDM signals utilizing the loop. The loop based on EAM-PLL can provide excellent tolerance range （〉 5 dB） of the OSCR of the source laser, and the recovered clock signal exhibits low rms jitter over a dynamic input optical power range of 15 dB.     

新型功能性显影促进剂的合成

以6-氨基苯并咪唑和苯基巯基三唑为吸附基团,以环状酰肼为显影促进基团,合成了两个新型功能性显影促进剂,其结构经IR,MS和元素分析确证。     

新型DAR黄成色剂的合成

以黄成色剂为母体,环状酰肼为显影促进基团,分别以6-氨基苯并咪唑和苯基巯基三氮唑为吸附基团,合成了2种新型DAR成色剂,产率分别为60.8%和48.2%。其结构经IR、1HNMR、MS和元素分析测试技术得到确证。实验结果表明,合成的DAR成色剂在提高感光度时不会增大灰雾密度。     

Multiwavelength All-Optical Clock Recovery of Non-Return-to-Zero Data

A novel scheme of all-optical clock recovery from mutiwavelength non-return-to-zero （NRZ） data stream is proposed and demonstrated. The chirp induced by a chirped fibre Bragg grating and a semiconductor optical amplifier is used to enhance the clock. The clock is recovered after injecting the enhanced signal into the scheme based on the stimulated Brillouin scattering. The experiment is carried out and the dual-wavelength clock is recovered. This novel scheme can realize clock recovery of multiwavelength NRZ signal in the total wavelength range of 3.3nm. This clock recovery technology is transparent to the data bit rate and modulation format, also without pattern dependence.     

不同湿度条件下N、Si共掺杂DLC膜的摩擦学性能研究

采用射频化学气相法沉积了氮、硅共掺杂类金刚石碳膜(N-Si-DLC).用X射线光电子能谱仪、拉曼光谱仪、表面形貌仪及扫描电子显微镜等对薄膜结构进行了表征,用球-盘往复摩擦试验机考察了不同湿度(RH为15%,45%和75%)空气中薄膜与316L不锈钢球配副的摩擦学性能.结果表明:与Si-DLC相比,N-Si-DLC膜内sp~2C成分含量较高,N主要以C=N、C≡N、Si-N键形式存在于膜内;膜的内应力低,硬度和杨氏模量较低;含N量少的N-Si-DLC膜显示出更低的摩擦与磨损,其摩擦学性能对湿度的变化表现出较低的敏感性.