Optical homodyne receiver utilizing image rejection in FSK/ASK re-modulation WDM-PON

Optical frequency shift keying （FSK） homodyne detection utilizing image rejection in FSK/amplitude shift keying （ASK） re-modulation wavelength-division-multiplexed passive optical network （WDM-PON） is proposed and demonstrated. Image rejection is adopted to achieve better performance. We show the result in back-to-back and 40-km distance respectively and apparent improvement is obtained in the latter situation by using image rejection. Several factors which affect the image rejection receiver are analyzed in order to find out the optimum parameters. Result shows that the presented scheme is suitable for super long reach access network, especially for future metro access network.     

Analysis of smooth phase modulation formats compared with conventional QPSK and BPSK using coherent detection

Novel optical offset quadrature phase shift keying (OQPSK) and improved minimum-shift keying (MSK) modulation schemes to smooth optical phase hopping for high speed fiber optics transmission are proposed. Simulations have been done among the MSK, OQPSK, quadrature phase shift keying (QPSK), and binary phase-shift keying (BPSK) modulation formats at 40 Gb/s over 100-km transmission link using coherent detection. Simulation results present good performances to elevate chromatic dispersion tolerance and reduce the influence of nonlinear effects by adopting the smooth phase modulation formats. Inter-symbol interference decreases for the fast side-lobe property and tight spectrum as a result of avoding the π phase shift and reducing envelop fluctuation.     

Diode-pumped Solid-state Cr~(4 )∶Nd∶YAG/KTP Green Laser

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All solid-state, injection-seeded Ti: sapphire ring laser

In this letter, we present an all solid-state, injection-seeded Ti:sapphire laser. The laser is pumped by a laser diode pumped frequency-doubled Nd:YAG laser, and injection-seeded by an external cavity laser diode with the wavelength between 770 and 780 nm. The single longitude mode and the doubling efficiency of the laser are obtained after injection seeding. The experimental setup and relative results are reported.It is a good candidate laser source for mobile differential absorption lidar (DIAL) system.     

乙醇胺功能化石墨烯的制备与表征

乙醇胺在温和条件下与氧化石墨烯反应, 然后经水合肼还原得到功能化的石墨烯. 干燥的功能化石墨烯经超声处理后, 可稳定分散于水、乙醇、丙酮和N,N二甲基甲酰胺(DMF)等溶剂中. 原子力显微镜(AFM)、透射电镜(TEM)分析表明功能化石墨烯平均厚度为3～4 nm. 傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)、X射线衍射(XRD)对功能化石墨烯的结构分析表明: 乙醇胺与氧化石墨烯发生了化学反应, 并通过共价键连接到石墨烯的六元环上. TG结果表明功能化石墨烯的热稳定性比氧化石墨烯有所提高, 但低于还原氧化石墨烯.     

微波辅助萃取-超高效液相色谱-四极杆/静电场轨道阱高分辨质谱法快速测定食品接触塑料制品中48种污染物残留

利用超高效液相色谱-四极杆/静电场轨道阱高分辨质谱法（UPLC-Q Orbitrap HRMS）的同时定性定量功能,建立了食品接触塑料制品中48种污染物残留的检测方法。用甲醇提取目标化合物,经微波辅助萃取,采用CAPCELL PAK MG Ⅱ C18色谱柱（150 mm×2.0 mm,5 μm）分离,以0.04%（v/v）甲酸甲醇溶液和含0.04%（v/v）甲酸与20 mmol/L（v/v）乙酸铵的水溶液为流动相进行梯度洗脱,在加热电喷雾电离（HESI）源、全扫描/实时二级质谱（Full MS/dd-MS²）监测模式下进行检测。结果表明,48种目标化合物在各自范围内线性关系良好,相关系数（r）均≥ 0.9950;检出限为0.1~1.0 μg/kg;平均加标回收率为71.2%~108.8%,相对标准偏差为2.2%~11.8%（n=6）。该法具有操作简单快捷、灵敏度高等优点。     

中国制氢技术的发展现状

氢能是一种高效清洁的二次能源,在实现“碳中和”目标中起重要作用。随着制氢规模不断扩大、制氢成本不断降低,氢能将有望与电能共同成为二次能源主体,通过氢电互补推动我国能源结构转型、降低碳排放、保障我国能源安全。目前,我国已成为世界第一大产氢国,主要有三类工业制氢路线:化石燃料重整制氢、工业副产氢和清洁能源电解水制氢。依托清洁能源发展起来的其他制氢新技术,如太阳能光解水制氢、生物质制氢、核能制氢等也受到广泛研究和关注。此外,制氢系统组成复杂,建模和优化难度高,人工智能在制氢系统的预测、评估和优化方面表现出独特的优势,受到国际学者的关注。本文结合最新研究进展,对上述制氢路线的发展情况进行了综述,并通过技术成熟度、经济性和环保性比较,结合国情对我国未来氢气供应结构做出展望。同时,本文综述了人工智能在制氢系统中的最新应用进展,以期为我国制氢工艺发展提供新思路。     

TEMPO/TCC as a Chemo Selective Alternative for the Oxidation of Hyaluronic Acid

Hyaluronic acid (HA)-based hydrogels are very commonly applied as cell carriers for different approaches in regenerative medicine. HA itself is a well-studied biomolecule that originates from the physiological extracellular matrix (ECM) of mammalians and, due to its acidic polysaccharide structure, offers many different possibilities for suitable chemical modifications which are necessary to control, for example, network formation. Most of these chemical modifications are performed using the free acid function of the polymer and, additionally, lead to an undesirable breakdown of the biopolymer’s backbone. An alternative modification of the vicinal diol of the glucuronic acid is oxidation with sodium periodate to generate dialdehydes via a ring opening mechanism that can subsequently be further modified or crosslinked via Schiff base chemistry. Since this oxidation causes a structural destruction of the polysaccharide backbone, it was our intention to study a novel synthesis protocol frequently applied to selectively oxidize the C6 hydroxyl group of saccharides. On the basis of this TEMPO/TCC oxidation, we studied an alternative hydrogel platform based on oxidized HA crosslinked using adipic acid dihydrazide as the crosslinker.     

上海激光康普顿散射伽马源的发展和展望

激光康普顿散射(Laser Campton Scattering, LCS)光源,是一种基于相对论电子束与激光光子相互作用的新型X-ray或Gamma-ray光源。它具有能量高、波长短、脉冲快和峰值亮度高的特性,已成为国际先进光源技术的重要选项之一。本文介绍了激光康普顿散射光源的产生原理、国内外发展现状以及目前国际上运行和在建的激光康普顿散射光源装置,其中重点介绍了上海光源二期正在建设的上海激光电子伽马源(Shanghai Laser Electron Gamma Source, SLEGS)装置,以及在这一光源装置上可以开展的核物理、核天体物理、核废料处理及核医学应用等研究。随着上海软X射线自由电子激光试验装置(Soft X-ray Free Electron Laser, SXFEL)升级为用户装置,以及未来十三五国家重大科技基础设施-硬X射线自由电子装置(Shanghai HIgh repetition rate XFEL aNd Extreme light facility,SHINE)的建设完成,基于直线电子加速器(LINear ACcelator, LINAC)的康普顿散射光源的伽马能量将会达到GeV量级的高能量。超短脉冲、高极化度、高通量的激光康普顿散射光源将迎来新的发展机遇,基于康普顿伽马光源的核物理、天体物理、粒子物理及应用基础研究也必将迈上一个新台阶。     

Generation of coherent optical multi-carriers using concatenated,dual-drive Mach-Zehnder and phase modulators

The generation of coherent optical subcarriers based on a concatenated dual-drive Mach-Zehnder intensity modulator（IM） and two phase modulators（PMs） is proposed and experimentally demonstrated.The modulation index and DC bias of PM+IM modulation are theoretically investigated.Theoretical analysis and numerical study are also carried out to examine the proposed scheme.We use 25-GHz RF synchronous sinusoidal signals to drive cascaded two-stage PMs and IM,through which we generate 28 subcarriers with peak power fluctuations less than 4 dB.The measured tone-to-noise ratio of the subcarrier is higher than 40 dB.The experimental results show that for 100-Gb/s polarization multiplexing QPSK signal,the receiver sensitivity of the back-to-back signal is -28.6 dBm,and the power penalty is lower than 1 dB after 100-km transmission at the BER of 1×10^-9.