Distributed Measurement of Birefringence by P-OTDR Assisted with Piezoelectric Polarization Controller

We propose a new polarization sensitive optical time domain reflectometry （P-OTDR） setup assisted with a piezoelectric polarization controller （PPC）. The input state of polarization can be changed by varying the voltage of PPC without any rotatable instrument, and only one optical receiver is used to detect the backward beam. We measure a single mode fibre and get the distribution of birefringence along the SMF.     

Investigation on Characteristics and the Improving Method of Double Loop Optical Buffer

We establish an equivalent cascaded semiconductor optical amplifier system model to analyze the characteristics of the double loop optical buffer （DLOB）. The theoretical analysis finds that the performance of the DLOB can be improved by inserted amplifying process in an interval of some cycles. The experiment demonstrates that the buffered cycles can be improved from 20 to 50 and the bit error rate is less than 10-9 by inserting amplifying process in an interval of about 10 cycles.     

基于多种控制机理的湍流爆炸燃烧模型研究

本文针对狭长受限空间油气爆炸燃烧发生、发展过程特点,建立不同控制机理制约不同反应步的分步反应湍流燃烧模型。该燃烧模型的基本思想在于将化学反应分为两步进行,各步的控制机理不同,各步释放的能量也不同．采用分解、混合、反应的分步方式来模拟油气爆炸燃烧过程,通过实验和数值计算结果表明,该模型能较好解决湍流爆炸燃烧过程的数值模拟问题,其结果与实验吻合很好。     

Cr/MCM-41催化剂的制备及其用于丙烷非氧化脱氢反应

实验分别采用连续吸附法和传统浸渍法制备Cr/MCM-41催化剂（分别记为Cr/MCM-41-ad和Cr/MCM-41-imp）,将制备的Cr/MCM-41催化剂用于丙烷非氧化脱氢制丙烯反应,并对反应过程中的温度、压力、空速等反应条件进行优化,在合适的条件即反应温度为630℃、压力为0.1 MPa、空速为4500 mL·h^-1·g^-1下比较两种方法制备的催化剂在丙烷脱氢制丙烯反应的催化性能.我们采用XRD、SEM-mapping、XPS、UV-vis、H₂-TPR等表征手段对催化剂上α-Cr₂O₃晶体粒径、活性组分及分布等进行表征分析,结果表明Cr/MCM-41-ad和Cr/MCM-41-imp中同时均存在Cr（VI）、Cr（Ⅲ）和α-Cr₂O₃.其中XRD和SEM-Mapping结果可知,Cr/MCM-41-ad上获得的α-Cr₂O₃晶体粒径较小且分散性好;通过UV-vis、XPS和TPR结果证明Cr/MCM-41-imp催化剂存在非活性孤立态Cr（VI）,较难还原,影响其反应活性.相比之下,吸附法制备的催化剂使Cr高分散,可避免形成非活性孤立态Cr（VI）,进而提高丙烷脱氢催化活性.因此,吸附法制备的铬基催化剂用于丙烷脱氢制丙烯有一定的借鉴作用.     

浊点萃取-火焰原子吸收光谱法测定人尿液中的痕量铅

以双硫腙作为络合剂、聚乙二醇辛基苯基醚(TritonX-100)为非离子表面活性剂,建立浊点萃取-火焰原子吸收光谱测定尿液中痕量铅的方法。探讨了络合剂用量、平衡时间、pH值、TritonX-100用量、冰浴时间等因素对萃取效率的影响。结果表明:该方法对铅的最大富集倍数约为40倍,检出限为0.06μg·L-1(n=11)。回收率在96.7%~101%,线性范围为0~1.00μg·mL-1。利用该方法测定尿液中痕量铅的含量,结果令人满意。     

Generalized Principal-State-of-Polarization Analysis and Matrix Model for Piezoelectric Polarization Controllers

We introduce a generalized concept of principal state of polarization （PSP） to analyse the piezoelectric polarization controller （PPC） and find each PPC unit can be described by a rotation matrix determined by the PSP. Our PPC has three components, each made of a jaw and a piezoelectric actuator with the squeezing direction tilted 0°, 45° and 0°, which are driven by a tunable power supply. We demonstrate that all the polarization rotation angles are linear to driving voltages and the PSP of unit 2 is nearly orthogonal to others which are almost equal. Taking some approximate treatments we obtain the matrix model of our PPC with respect to three driving voltages. The average error of our theoretical model is 1.51°, and the polarization response time is 〈50 μs, which is promising to realize an open-loop control of polarization.     

An Encryption-Decryption Method Using XOR Gate Based on the XPM between O-Band and C-Band Light Waves

An all-optical encryption-decryption method using an exclusive-or gate based on the cross-phase modulation between O-band and C-band light waves is proposed. The feasibility of the encryptionecryption technique is verified by handling binary signals at 2.5 Gbps, with less than 3dB penalty of extinction ratio and i dB polarization dependent loss.     

无定形氧化铁层在纳米多孔BiVO4的光电化学分解水反应中的作用

通过"人工光合成"过程,将太阳能转化成氢能的形式加以存储和利用,是替代传统化石能源的清洁能源的制备有效途径.其中,光电化学分解水是氢能制备的最有潜力的路径之一.n型BiVO4由于具有丰富的储量、较窄的带隙以及合适的能带位置,被称为光电化学领域的研究热点.然而,未修饰的BiVO4光阳极性能并不理想,主要原因在于载流子复合严重、导电性差以及表面催化动力学低等性质的制约.科研工作者们针对这些方面已进行了非常多的研究,例如与电子传输层的复合、产氧电催化剂的担载以及异质结的构建等.其中表面动力学和电荷分离的同时提升是更理想的改善BiVO4光阳极性能的方法.我们在上述研究基础上,采用光化学沉积法在纳米多孔BiVO4电极表面担载无定形氧化铁层,将电极在1.23 V vs.RHE电位下的光电流提升至2.52 mA/cm2,是初始光电化学性能的3倍.采用间歇光照计时电流(i-t)测试,电化学交流阻抗谱(EIS),X射线光电子能谱(XPS),原位和非原位的X射线精细结构能谱(in-situ and ex-situ XAFS)等表征手段研究了无定形氧化铁层的成分和光电化学反应过程中的价态变化,从而分析出光电化学性能提升的原因.间歇光照i-t测试和EIS测试结果表明,无定形氧化铁沉积在BiVO4使电荷累积减少,复合率降低.XPS测试结果发现无定形氧化铁层存在少量的二价铁成分.通过原位XAFS测试发现,BiVO4/FeOx电极中Fe原子的价态在光照和施加外加偏压条件下会有价态的升高,而撤去光照和偏压后Fe原子的价态状态与最初非原位的测试结果重合.这样的结果证明了无定型氧化铁层在光电化学反应过程中由于二价铁成分的存在,能够很好的通过价态改变实现空穴的吸附和传输,即吸附空穴,被空穴氧化成三价或四价,同时结合自身电催化活性,促进表面分解水反应的进行.而水的氧化反应结束时,则伴随着二价铁离子的再生成.这种反应机理为开发更高效的电催化剂,匹配光电极使用,有着重大的指导意义.     

Mueller matrix analysis for all optical fiber co-existence of birefringence-polarization dependent gain-mode coupling at a single wavelength

Birefringence (polarization-related phase-shift), polarization dependent gain (PDG) and mode coupling are three factors that may synchronously influence the transmission of single-wavelength polarized light in optical fibers. This paper obtains a new Mueller matrix analysis, which can be used under conditions that all these three factors are existing and changing. According to our transmission model, the state of polarization (SOP) changes along an optical microstructure fiber with co-existence of birefringence-PDG-mode coupling were simulated. The simulated results, which show the phenomena of SOP constringency, are in good agreement with previous theoretical analyses.