一种新型有机电致微腔结构的双模发射

采用结构Glass／DBR／ITO／NPB／NPB：Alq／Alq／Al制作了有机微腔电致发光器件。将空穴传输材料与发光材料以一定比例混合作为发光层，为了便于对比，在不改变有机层的膜厚的情况下同时制作了传统的异质结微腔器件，发现两种器件的发光光谱有很大不同，器件的复合效率与传统的异质结器件相比也得到了很大提高，这是因为将两种有机材料混合能消除界面势垒，提高器件的复合效率，从而提高了器件的发光性能，实现了微腔双模发射，且两个模式的半峰全宽分别为8nm和12nm。通过进一步优化器件结构可以实现微腔白光发射。     

柔性衬底白色有机电致发光器件的制备及其性能

采用以ITO为导电层的柔性透明PET基片作为衬底,以2-(2-羟基苯基)苯并噻唑螯合锌(Zn(BTZ),)作为发光层制备出结构为PET／ITO／PVK：TPD／Zn(BTZ)2／Al明亮的近白色柔性有机小分子电致发光器件。发光的色坐标值为x=0．242,y=0．359,在25V的直流电压驱动下,亮度为1000cd／m^2,量子效率达到了0．30％。并进一步在Zn(BTZ)2中掺入橙红色染料Rubrene,制成PET／ITO／PVK：TPD／Zn(BTZ)2：Rubrene／Al结构器件。实现了纯白色发光(色坐标值：x=0．339,y=0．339),非常接近于白色等能点,驱动电压为25V时器件的亮度达1200cd／m^2,且量子效率达0．35％。最后对器件的发光性能及机理进行了深入的研究和探讨。     

柔性有机电致发光器件导电基板的工艺性能

在聚对苯二甲酸乙二醇酯(PET)柔性衬底上采用直流磁控溅射技术制备了氧化铟锡(ITO)透明导电薄膜,研究了衬底温度、溅射功率和溅射压强等工艺条件对薄膜光电性能的影响,并利用原子力显微镜(AFM)表征了衬底及ITO薄膜的表面形貌。结果表明,在PET衬底温度50℃、溅射功率100W和溅射压强2.66×10-1Pa的条件下,可以得到低方阻(50Ω/□)和高透过率(>90%)的透明导电薄膜。以此柔性ITO衬底为阳极,制备了结构为PET/ITO/NPB/Alq3/Mg∶Ag的柔性有机电致发光器件,在驱动电压为13V时,器件的发光亮度达到了2834cd/m2。     

稀土有机电致发光器件

我们研制了用有机材料Tb(AcA)3·phen作为发射层的绿色发光二极管,两层结构为玻璃衬底ITO/芳香族二胺类衍生物TPD/Tb(AcA)3·phen/A1。各功能层均用真空热蒸发的方法制备。在正向直流偏压驱动下获得了Tb3+的特征发光,同时还发现一个峰位425um的蓝光发射,它来源于空穴输运层TPD。在室温条件下器件的阈值电压为4V,当驱动电压提高到16V时,器件的最高发光亮度达到200cd/m2,同时在相同条件下制备了结构为玻璃衬底ITO/芳香族二胺类衍生物TPB/Tb(AcA)3·phen/A1的器件,通过对两种器件光谱及电学特性的测量、比较与分析,探讨了有关稀土有机电致发光的发光机理等问题。     

掺杂DCJTB聚合物电化学池（LEC）的发光性质

通过在聚合物电化学池(LEC)发光器件的发光材料MEH-PPV中掺杂红光染料DCJTB,对LEC器件的发光性质进行研究。基于器件结构为ITO/MEH-PPV PEO LiCF3SO3/Al的薄膜LEC器件,其电致发光峰在570nm左右,通过在MEH-PPV与PEO的混合膜中掺杂不同比例的红光染料DCJTB,随着掺杂比例的增加,器件的发光峰由570nm向红光波段移动,通过控制DCJTB的掺杂比例制备了发光峰在570~650nm连续变化的LEC电致发光器件。对其分析认为从LEC主体发光聚合物MEH-PPV到染料DCJTB间发生了良好的能量传递。     

聚苯胺/ZnO纳米线薄膜材料作为发光层的柔性光电器件 及其发光机理

综合氧化锌纳米线(ZnO NWs)的光学活性与聚苯胺(PANI)的空穴传输特性,设计并制备了一种聚合物/ZnO纳米线电致发光材料,并对其发光特性进行了研究。通过高分子络合软模板法,将有序的单晶ZnO NWs均匀生长在覆有铟锡氧化物(ITO)涂层的柔性聚乙烯对苯二甲酸乙二醇酯(PET)衬底上并嵌入PANI薄膜,获得了电致发光薄膜材料和有机/无机异质结实验器件ITO/(ZnO NWs-PANI)。有机/无机异质结器件电致发光可调,在相对低的开启电压下呈现室温蓝紫外发光,并且ZnO NWs表面覆盖PANI增加了蓝紫外发光的强度和稳定性;而无PANI的ZnO NWs阵列具有450 nm处的缺陷发射峰,这可能是电子从扩展态锌间隙Zn_i到价带的跃迁引起的。这些结果表明,基于PANI/ZnO纳米线的复合材料在柔性光电器件方面的应用极具潜力。     

新型共轭聚合物PFO-BT15发光二极管的电老化研究

PFO-BT15是一种电致发光中心波长为550 nm的新型共轭高分子聚合物材料,将其制成发光二极管器件,结构为ITO玻璃/聚合物PEDOT(120 nm)/有机聚合物PFO-BT15(80 nm)/Ba(4 nm)/Al(200 nm),用环氧树脂对阴极侧进行了封装,以减少氧气和水分的进入,从而影响器件的发光性能。在室温环境下对同样的器件进行不同电流密度的电老化处理,记录器件的电流电压曲线,再对老化的样品做电致发光和喇曼光谱测试。实验发现：一方面,通过器件恒定电流的大小影响器件的电压变化速度;另一方面,器件经过一定长时间的电老化,电致发光中心波长变化较小。通过啦曼光谱的测试,推断是因为PEDOT阳极的破损导致了器件的最终发光失败,而器件发光层材料的结构保持相对稳定,说明这种结构的聚合物有着相对稳定的光电性能,对于提高材料发光的稳定性提供了有价值的信息,有助于其他高效发光材料的合成以及稳定性的提高。     

全溶液法制备有机发光二极管及PEIE浓度对器件光电性能的影响

对溶液化发光层成膜参数及电子传输层浓度进行调控,优化发光层成膜效果及器件发光性能,同时使用导电聚合物聚（3,4-乙烯二氧噻吩）-聚苯乙烯磺酸（PEDOT:PSS）作为透明阳极,刮涂导电银浆作为阴极,通过全溶液法制备了高效率的OLED。研究发现,发光层成膜参数的调整有效改善了其成膜效果。且适当的电子传输层材料浓度可以改善器件的载流子注入平衡,有效降低阴极的功函数,提高器件的发光性能;酸后处理的PEDOT:PSS薄膜导电性大大提升,在可见光范围的透过率与ITO相当。全溶液制备的发光器件最大电流效率为1.441 cd/A,与以ITO为电极的器件相比,增加了近50倍。     

共轭聚合物MEH-PPV的固态阴极射线发光

在有机／无机异质结ZnS／MEH－PPV／ZnS器件中，交流驱动条件下，实现了共轭聚合物MEH－PPV的固态阴极射线发光，器件的发光光谱与MEH－PPV的光致发光谱相同。电子经过ZnS层加速后，成为过热电子，这些过热电子直接碰撞激发MEH－PPV而发光。在日光灯照明下，可以看到器件的均匀发光。     

绿色陶瓷厚膜电致发光器件研究

报道了采用高介电常数的陶瓷厚膜作绝缘层、ＺｎＳ：Ｅｒ,Ｃ１作为发光层的绿色薄膜电致发光器件（ＣＴＦＥＬ）。器件结构为陶瓷基片／内电极／陶瓷厚膜／发光层（ＺｎＳ：Ｅｒ,Ｃ１）／透明电极（ＺｎＯ：Ａ１）。制备的器件在市电频率驱动下发出明亮的绿光,测量了器件的电致发光（ＥＬ）光谱和亮度－电压曲线,研究了发光机理和效率－电压等特性。     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser

Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser.     

Propagation of Helmholtz-Gauss beams in weak turbulent atmosphere

Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored.     

An effective method for reducing speckle noise in digital holography

An effective method for reducing the speckle noise in digital holography is proposed in this paper.Different from the methods based on classical filtering technique,it utilizes the multiple holograms which are generated by rotating the illuminating light continuously.The intensity images reconstructed by a series of holograms generated by rotating the illuminating light possess different speckle patterns.Hence by properly averaging the reconstructed intensity fields,the speckle noises can be reduced greatly.Experimental results show that the proposed method is simple and effective to reduce speckle noise in digital holography.     

Influence of purity of HfO2 on reflectance of ultraviolet multilayer

The impurities in two kinds of HfO2 materials and in their corresponding single layer thin films were determined through glow discharge mass spectrum technology and secondary ion mass spectrometry(SIMS) equipment respectively.It was found that ZrO2 was the main impurity in the two kinds of HfO2 either in the original HfO2 materials or in the electron beam deposited films.In addition,the difference of Zr content in the two kinds of HfO2 single laver films was much laxger than that of the other impurities such as Ti and Fe.which showed that it was just ZrO2 that made the difference between the optical performance of the film products including the two kinds of HfO2.With these two kinds of HfO2 and the same kind of SiO2.we deposited HfO2/SiO2 multilayer reflective coatings at the wavelength of 266 nm.Experimental results showed that the reflectances of these two mirrors were about 99.85% and 99.15% respectively,which agreed well with the designed results what were based on the optical constants obtained from the corresponding single layer thin films.     

Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.