Wei CHEN   Shihe YANG  

      摘要 + ：(浏览：2989次) | 此论文可免费阅读 (可能需要登录)

In this paper, we reviewed recent systematic studies of using ZnO nanotetrapods for photoanodes of dye-sensitized solar cells (DSSCs) in our group. First, the efficiency of power conversion was obtained by more than 3.27% by changes of conditions of dye loading and film thickness of ZnO nanotetrapod. Short-circuit photocurrent densities (Jsc) increased with the film thickness, Jsc would not be saturation even the film thickness was greater than 35 μm. The photoanode architecture had been charactered by good crystallinity, network forming ability, and limited electron-hopping interjunctions. Next, DSSCs with high efficiency was devised by infiltrating SnO2 nanoparticles into the ZnO nanotetrapods photoanodes. Due to material advantages of both constituents described as above, the composite photoanodes exhibited extremely large roughness factors (RFs), good charge collection, and tunable light scattering properties. By varying the composition of the composite photoanodes, we had achieved an efficiency of 6.31% by striking a balance between high efficiency of charge collection for SnO2 nanoparticles rich films and high light scattering ability for ZnO nanotetrapods rich films. An ultrathin layer of ZnO was found to form spontaneously on the SnO2 nanoparticles, which primarily was responsible for enhancing open-circuit photovoltage (Voc). We also identified that recombination in SnO2/ZnO composite films was mainly determined by ZnO shell condition on SnO2, whereas electron transport was greatly influenced by the morphologies and sizes of ZnO crystalline additives. Finally, we applied the composite photoanodes of SnO2 nanoparticles/ZnO nanotetrapods to flexible DSSCs by low temperature technique of “acetic acid gelation-mechanical press-ammonia activation.” The efficiency has been achieved by 4.91% on ITO-coated polyethylenenaphtalate substrate. The formation of a thin ZnO shell on SnO2 nanoparticles, after ammonia activation, was also found to be critical to boosting Voc and to improving inter-particles contacts. Mechanical press, apart from enhancing film durability, also significantly improved charge collection. ZnO nanotetrapods had been demonstrated to be a better additive than ZnO particles for the improvement of charge collection in SnO2/ZnO composite photoanodes regardless of whether they were calcined.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2011年第4卷第1期 pp.24-44      

Zongyuan LIU   Sheng LIU   Kai WANG   Xiaobing LUO  

      摘要 + ：(浏览：2804次) | 此论文可免费阅读 (可能需要登录)

The status and prospects for high-power, phosphor-based white light-emitting diode (LED) packaging have been presented. A system view for packaging design is proposed to address packaging issues. Four aspects of packaging are reviewed: optical control, thermal management, reliability and cost. Phosphor materials play the most important role in light extraction and color control. The conformal coating method improves the spatial color distribution (SCD) of LEDs. High refractive index (RI) encapsulants with high transmittance and modified surface morphology can enhance light extraction. Multi-phosphor-based packaging can realize the control of correlated color temperature (CCT) with high color rendering index (CRI). Effective thermal management can dissipate heat rapidly and reduce thermal stress caused by the mismatch of the coefficient of thermal expansion (CTE). Chip-on-board (CoB) technology with a multilayer ceramic substrate is the most promising method for high-power LED packaging. Low junction temperature will improve the reliability and provide longer life. Advanced processes, precise fabrication and careful operation are essential for high reliability LEDs. Cost is one of the biggest obstacles for the penetration of white LEDs into the market for general illumination products. Mass production in terms of CoB, system in packaging (SiP), 3D packaging and wafer level packaging (WLP) can reduce the cost significantly, especially when chip cost is lowered by using a large wafer size.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2009年第2卷第2期 pp.119-140      

Li PENG   Jiang TANG   Mingqiang ZHU  

      摘要 + ：(浏览：2539次) | 此论文可免费阅读 (可能需要登录)

The increasing demand for sustainable and green energy supply spurred the surging research on highefficiency, low-cost photovoltaics. Colloidal quantum dot solar cell (CQDSC) is a new type of photovoltaic device using lead chalcogenide quantum dot film as absorber materials. It not only has a potential to break the 33% Shockley-Queisser efficiency limit for single junction solar cell, but also possesses low-temperature, high-throughput solution processing. Since its first report in 2005, CQDSCs experienced rapid progress achieving a certified 7% efficiency in 2012, an averaged 1% efficiency gain per year. In this paper, we reviewed the research progress reported in the last two years. We started with background introduction and motivation for CQDSC research.We then briefly introduced the evolution history of CQDSC development as well as multiple exciton generation effect. We further focused on the latest efforts in improving the light absorption and carrier collection efficiency, including the bulk-heterojunction structure, quantum funnel concept, band alignment optimization and quantum dot passivation. Afterwards, we discussed the tandem solar cell and device stability, and concluded this article with a perspective. Hopefully, this review paper covers the major achievement in this field in year 2011-2012 and provides readers with a concise and clear understanding of recent CQDSC development.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第4期 pp.358-370      

Dehua XIONG   Wei CHEN  

      摘要 + ：(浏览：2346次) | 此论文可免费阅读 (可能需要登录)

Tandem structured dye-sensitized solar cells (DSSCs) can take full advantage of sunlight, effectively broadening the absorption spectrum of the cell, resulting in a higher open circuit voltage or short circuit current than that of the conventional DSSC with single light absorber. The theoretical maximum efficiency is therefore suggested to be over the Schottky-Queisser limit of 33%. Accordingly, tandem design of DSSC is thought to be a promising way to break the performance bottleneck of DSSC. Besides, the tandem designs also broaden the application diversity of DSSC technology, which will accelerate its scale-up industrial application. In this paper, we have reviewed the recent progress on photo-electrochemical applications associated with kinds of tandem designs of DSSCs, in general, which are divided into three kinds: “ntype DSSC + n-type DSSC,” “n-type DSSC + p-type DSSC” and “n-type DSSC + other solar conversion devices.” The working principles, advantages and challenges of these tandem structured DSSCs have been discussed. Some possible solutions for further studies have been also pointed out together.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第4期 pp.371-389      

Jiarui HUANG   Feng TANG   Cuiping GU   Chengcheng SHI   Muheng ZHAI  

      摘要 + ：(浏览：1969次) | 此论文可免费阅读 (可能需要登录)

Nanoflake-based flower-like CuO nanostructures have been synthesized through thermal decomposition of [Cu(NH3)4]2+ solution without any surfactants and catalysts at low temperature. The products are characterized by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM). The possible formation process based on the aggregation-recrystallization mechanism is proposed. Finally, the obtained flowerlike CuO hierarchical nanostructures have been used as the photocatalyst in the experiments. It is found that the asprepared flower-like CuO hierarchical nanostructures exhibit superior photocatalytic property on photocatalytic decomposition of Rhodamine B due to their hierarchical structures.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第4期 pp.429-434      

Jinjie CHEN   Bo LIU   Hao ZHANG  

      摘要 + ：(浏览：1917次) | 此论文可免费阅读 (可能需要登录)

The current status of the fiber Bragg grating (FBG) sensor technology was reviewed. Owing to their salient advantages, including immunity to electromagnetic interference, lightweight, compact size, high sensitivity, large operation bandwidth, and ideal multiplexing capability, FBG sensors have attracted considerable interest in the past three decades. Among these sensing physical quantities, temperature and strain are the most widely investigated ones. In this paper, the sensing principle of FBG sensors was briefly introduced first. Then, we reviewed the status of research and applications of FBG sensors. As very important for industrial applications, multiplexing and networking of FBG sensors had been introduced briefly. Moreover, as a key technology, the wavelength interrogation methods were also reviewed carefully. Finally, we analyzed the problems encountered in engineering applications and gave a general review on the development of interrogation methods of FBG sensor.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2011年第4卷第2期 pp.204-212      

Wen-Liang GONG   Zhe HU   Chong LI   Guo-Feng ZHANG   Tao CHEN   Matthew P. ALDRED   Zhen-Li HUANG   Ming-Qiang ZHU  

      摘要 + ：(浏览：1725次) | 此论文可免费阅读 (可能需要登录)

This paper reported the synthesis of hexaarylbiimidazole-tetraphenylethene (HABI-TPE) conjugated photochromic fluorophore, which simultaneously exhibited photochromic property, condensed state enhanced emission and reversible fluorescence switching. Upon UV irradiation, a green species with a broad absorption band between 550 and 800 nm ( the absorption maximum at 697 nm ) was observed, which readily faded to colorless in the darkness. HABI-TPE launched strong fluorescence with the maximum emission wavelength at 520-580 nm under the excitation with 450-500 nm visible light in condensed state, which is in contrast to nonfluorescence in solution. The maximum emission wavelength in condensed state was dependent of excitation wavelength. More interestingly, HABI-TPE exhibited reversible fluorescence switching upon alternating irradiation with blue or near-UV light (wavelength less than 490 nm) and green light (more than 490 nm) in condensed state. Our evaluation demonstrated that HABI-TPE exhibited great photoswitchable fluorescence, which is a promising photoswitchable fluorophore for localization-based super-resolution microscopy, evidencing by resolving nanostructures with sub-100 nm resolution in polymethylmethacrylate films.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2013年第6卷第4期 pp.458-467      

Meirong SUI   Ping GONG   Xiuquan GU  

      摘要 + ：(浏览：1573次) | 此论文可免费阅读 (可能需要登录)

The emission of electrons from the surface of a solid caused by a high electric field is called field emission (FE). Electron sources based on FE are used today in a wide range of applications, such as microwave traveling wave tubes, e-beam evaporators, mass spectrometers, flat panel of field emission displays (FEDs), and highly efficient lamps. Since the discovery of carbon nanotubes (CNTs) in 1991, much attention has been paid to explore the usage of these ideal one-dimensional (1D) nanomaterials as field emitters achieving high FE current density at a low electric field because of their high aspect ratio and “whisker-like” shape for optimum geometrical field enhancement. 1D metal oxide semiconductors, such as ZnO and WO3 possess high melting point and chemical stability, thereby allowing a higher oxygen partial pressure and poorer vacuum in FE applications. In addition, unlike CNTs, in which both semiconductor and metallic CNTs can co-exist in the as-synthesized products, it is possible to prepare 1D semiconductor nanostructures with a unique electronic property. Moreover, 1D semiconductor nanostructures generally have the advantage of a lower surface potential barrier than that of CNTs due to lower electron affinity and the conductivity could be enhanced by doping with certain elements. As a consequence, there has been increasing interest in the investigation of 1D metal oxide nanostructure as an appropriate alternative FE electron source to CNT for FE devices in the past few years. This paper provides a comprehensive review of the state-of-theart research activities in the field. It mainly focuses on FE properties and applications of the most widely studied 1D ZnO nanostructures, such as nanowires (NWs), nanobelts, nanoneedles and nanotubes (NTs). We begin with the growth mechanism, and then systematically discuss the recent progresses on several kinds of important nanostructures and their FE characteristics and applications in details. Finally, it is concluded with the outlook and future research tendency in the area.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2013年第6卷第4期 pp.386-412      

Xiaojing Lu   Yin PENG   Zhengzheng HAN  

      摘要 + ：(浏览：1541次) | 此论文可免费阅读 (可能需要登录)

The treatment of wastewater that includes toxic organic pollutants such as dyes, phenoaniline, phenols and their derivatives is still a challenge due to their biorecalcitrant and acute toxicity to the widespread acceptance of water recycling. Three-dimensional (3D) Bi2WO6 microsphere was synthesized by the hydrothermal method using Bi(NO3)3 and Na2WO4 as raw materials. This structure exhibits high photocatalytic activity for the dyes, toxic organic compounds. The degradation of methlyene blue is 100% in 30 min, 4-nitrylphenol is 95% in 60 min and p-nitrylphenol is 95% in 75 min in ultraviolet (UV) light irradiation. 3D Bi2WO6 microsphere is also a good photocatalyst to treat the printing and dyeing sewage, and exhibits high repeatability. After being used the 20th time, Bi2WO6 still has high activity to degrade the printing and dyeing sewage, which is very important for a photocatalyst to be used in industry. This study will pave a new way to treat industry wastewater.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第4期 pp.439-444      

Heng WANG   Peng XIANG   Mi XU   Guanghui LIU   Xiong LI   Zhiliang KU   Yaoguang RONG   Linfeng LIU   Min HU   Ying YANG   Hongwei HAN  

      摘要 + ：(浏览：1501次) | 此论文可免费阅读 (可能需要登录)

A monobasal solid-state dye-sensitized solar cell (ssDSC) with mesoporous TiO2 beads was developed and an efficiency of 4% was achieved under air mass (AM) 1.5 illumination. Scattering properties and electron diffusion coefficients of TiO2 mesoporous beads and P25 nanoparticles were investigated. The results show that TiO2 mesoporous beads display higher scatterance than P25 nano-particles, and TiO2 mesoporous beads have higher electron diffusion coefficients (2.86×10-5 cm2·s-1) than P25 nano-particles (2.26×10-5 cm2·s-1).

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2013年第6卷第4期 pp.413-417      

Yong LIU   Ligong CHEN   Tianxiang XU   Jinglei MAO   Shangjian ZHANG   Yongzhi LIU  

      摘要 + ：(浏览：1440次) | 此论文可免费阅读 (可能需要登录)

In this paper, we review the recent progress in the optical signal processing based on the nonlinearity of semiconductor optical amplifiers (SOAs). The four important optical signal processing functional blocks in optical switching are presented, i.e., optical wavelength conversion, optical regeneration, optical logic, and optical format conversion. We present a brief overview of optical wavelength conversion, and focus on various schemes to suppress the slow gain recovery of the SOA and improve the operating speed of the SOA-based optical switches. Optical regeneration including re-amplification, re-shaping and re-timing is also presented. Optical clock recovery that is essential for optical regeneration is reviewed. We also report the recent advances in optical logic and optical format conversion, respectively. After reviewing the four important optical signal processing functional blocks, the review concludes with the future research directions and photonic integration.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2011年第4卷第3期 pp.231-242      

Wei JIN   Jian JU   Hoi Lut HO   Yeuk Lai HOO   Ailing ZHANG  

      摘要 + ：(浏览：1408次) | 此论文可免费阅读 (可能需要登录)

This paper reviews different types of air-silica photonic crystal fibers (PCFs), discusses their novel properties, and reports recent advances in PCF components and sensors as well as techniques for splicing PCFs to standard telecomm fibers.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2013年第6卷第1期 pp.3-24      

Wei CHEN   Jinyan LI   Shiyu LI   Zuowen JIANG   Haiqing LI   Jinggang PENG  

      摘要 + ：(浏览：1387次) | 此论文可免费阅读 (可能需要登录)

The high nonlinear photonic crystal fiber with pure silica core has been designed and fabricated, and the practical structure parameters of the fabricated fiber sample coincided precisely with the parameters we designed. The core diameter is 1.65 mm; the air hole diameter is 4.75 mm; the distance between the center of two holes is 5.35 mm; the zero dispersion wavelength of the fiber is 1120 nm; the dispersion at 800 nm is 288 ps? (nm?km)21; and the nonlinear coefficient of this photonic crystal fiber is 112 (W?km)21. The broadly spanning supercontinuum emission with a smooth spectrum stretching from 450 to 1400 nm was attained by the injection of 30 fs Ti:sapphire laser pulses into 2 m-long high linear photonic crystal fibers, with an energy up to 5 nJ at a pulse repetition rate of 100 MHz and a central wavelength of 800 nm.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2008年第1卷第1期 pp.75-78      

Kun CAO   Mingkui WANG  

      摘要 + ：(浏览：1358次) | 此论文可免费阅读 (可能需要登录)

Sensitizers have proven to be extremely important in determining the performance of dye-sensitized solar cells (DSCs). The design and understanding of sensitizers, especially D-π-A structured porphyrins, has become a recent focus of DSC research. In this perspective article, advances in the conception and performance of various sensitizers including ruthenium complexes, organic dyes and porphyrins are reviewed with respect to their structure and charge transfer dynamics at the dyesensitized mesopours heterojunction interface. In particular, the discussion focuses on the trends that perovskite would be the most effective and most likely to be used in DSCs combining with innovative hole transporting materials.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2013年第6卷第4期 pp.373-385      

Junjie DAI   Longyan YUAN   Qize ZHONG   Fengchao ZHANG   Hongfei CHEN   Chao YOU   Xiaohong FAN   Bin HU   Jun ZHOU  

      摘要 + ：(浏览：1337次) | 此论文可免费阅读 (可能需要登录)

A simple (2×2) pixelated flexible infrared nanosensor array based on carbon nanoparticles (CNPs) was fabricated through a simple and low-cost flame method. By integrated with a micro controller unit, the sensor array could detect power density of incident infrared light in real-time. The mechanism for the superior infrared sensing property of the flexible sensor array based on CNP was also studied in detail in this work.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第3期 pp.266-270      

Zhengxuan LI   Lilin YI   Weisheng HU  

      摘要 + ：(浏览：1320次) | 此论文可免费阅读 (可能需要登录)

In this paper, key technologies, system proposals and future directions of next generation passive optical networks stage 2 (NG-PON2) are reviewed. We first discuss the potential solutions for NG-PON2 standardization. Then we focus on time and wavelength division multiplexed PON (TWDM-PON), which is the primary solution selected by Full Service Access Network (FSAN). The key technologies in TWDM-PON configuration are analyzed, including how to improve the bandwidth capacity and power budget of the system, and choose upstream tunable transceiver, etc. Several system proposals are illustrated as candidates for NG-PON2 configuration.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2013年第6卷第1期 pp.46-56      

Yaoguang MA   Limin TONG  

      摘要 + ：(浏览：1316次) | 此论文可免费阅读 (可能需要登录)

This paper reviews our recent work on fabrication, optical characterization and lasing application of semiconductor nanowires, with brief introduction of related work from many other groups.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第3期 pp.239-247      

Jun ZHANG   Chengchun TANG  

      摘要 + ：(浏览：1315次) | 此论文可免费阅读 (可能需要登录)

Titania-Strontium titanate (TiO2-SrTiO3) nanotube array with heterostructure has been demonstrated as an efficient scaffold applied to quantum dot photoelectrochemical solar cells. Quantum dot CdS serviced as solar light absorbent is chosen as an example to illustrate superior performance and deposited on scaffolds by successive ionic layer adsorption and reaction (SILAR) technique. The photoelectrochemical performance of such solar cell is strongly dependent on the structure of heterostructured scaffolds. Only well-dispersed SrTiO3 nanocrystallites on TiO2 could improve the overall conversion efficiency. Transient absorption spectra and photoelectrochemical measurements show that the formation of SrTiO3 energy gradient between TiO2 and electrolyte slows down the rate of electronic injection from 19.3×108 to 6.30 ×108 s-1, while it greatly increases electronic collection efficiency via reduced charge recombination. Cadmium sulfide (CdS) quantum dots used to decorate TiO2-SrTiO3 (1 h hydrothermal treatment) electrode exhibits superior photoelectrochemical performance with nearly 70% increase in external quantum efficiency at 460 nm and also in overall cell conversion efficiency. The photostability and high efficiency properties of TiO2-SrTiO3 composites would enable its practical application in solar energy conversion devices.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2011年第4卷第1期 pp.93-102      

Yousaf KHAN   Xiangjun XIN   Aftab HUSSAIN   Liu BO   Shahryar SHAFIQUE  

      摘要 + ：(浏览：1306次) | 此论文可免费阅读 (可能需要登录)

We proposed and demonstrated the generation and transmission of 10-Gbps return-to-zero ON/OFF keying (RZ-OOK) signal using a new technique without pulse carving at transmitter. The new technique is characterized by a 3 dB built-in gain with better tolerance for chromatic dispersion in standard single mode fiber (SSMF). Fiber Bragg grating (FBG) is used as chromatic dispersion compensating device to investigate the tolerance of the proposed scheme. The simulation model of wavelength division multiplexing (WDM) based on OptiSystem.v.8.0 is presented. Simulation results show that there are error free transmission performance in a distance of 600 km with negligible power penalty and improved receiver sensitivity compared to conventional pulse carving approach.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第3期 pp.306-310      

Zhenrong ZHENG   Xutao SUN   Peifu GU   Xu LIU  

      摘要 + ：(浏览：1288次) | 此论文可免费阅读 (可能需要登录)

An objective lens composed of a spherical Fresnel zone plate mirror and aspheric mirrors is designed. The Fresnel zone plate with a spherical shape is analyzed, and the method to approximately replace the aspherical mirror with spherical Fresnel zone plate is deduced. The objective lens is designed with a single spherical Fresnel zone plate mirror and three aspherical mirrors. Under the condition of 1006magnification, 2.5 Fresnel number and 120u field angle, the modulation transfer function can reach above 40% at 0.6 line pairs/mm on the magnification side, and the distortion is less than 2.2%. This method can provide a reference for the application of Fresnel zone plate in visible light imaging, and has a bright future with the continuous development of the fabrication technique of Fresnel devices.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2008年第1卷第1期 pp.178-182      

Haitao YANG   Yilin CHANG   Jing WANG   Junyan HUO  

      摘要 + ：(浏览：1268次) | 此论文可免费阅读 (可能需要登录)

Automatic exposure (AE) is one of the indispensable functions of modern video cameras. According to the attention mechanism of human visual systems, peak regions in luminance histogram correspond to the region of no interest in an image. Based on this assumption, a new AE algorithm using the luminance histogram of an image is proposed in this paper. The algorithm finds the first two largest peak regions in the histogram and calculates the mean weighted luminance (MWL) of the entire image by weighting the luminance of pixels inside the two peak regions. The MWL is then used to control the exposure of video cameras. The weight of pixel luminance is decided by a set of quadratic curves, and the parameters of the quadratic curves are affected by the brightness of the image background. Fuzzy logic is also applied to optimize the practical AE systems. Results show that the proposed algorithm gives efficient exposure control over various scene tests.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2008年第1卷第3期 pp.285-291      

Weiming WANG   Jun YANG   Xin ZHU   Jamie PHILLIPS  

      摘要 + ：(浏览：1247次) | 此论文可免费阅读 (可能需要登录)

This paper describes our recent developments of intermediate-band solar cells, with a focus on the use of dilute alloys and nanostructured materials such as quantum dots (QDs). The concept of “full-spectrum” solar cells and their working mechanism with various material structures are first illustrated. A comprehensive review of ZnTe:Obased intermediate-band solar cells, including material growth, structural and chemical analysis, device modeling and testing, are presented. Finally, the progress and challenges of quantum-dot-based solar cells are discussed.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2011年第4卷第1期 pp.2-11      

Guangcun SHAN   Xinghai ZHAO   Mingjun HU   Chan-Hung SHEK   Wei HUANG  

      摘要 + ：(浏览：1245次) | 此论文可免费阅读 (可能需要登录)

The use of cavity to manipulate photon emission of quantum dots (QDs) has been opening unprecedented opportunities for realizing quantum functional nanophotonic devices and quantum information devices. In particular, in the field of semiconductor lasers, QDs were introduced as a superior alternative to quantum wells (QWs) to suppress the temperature dependence of the threshold current in vertical-external-cavity surfaceemitting lasers (VECSELs). In this work, a review of properties and development of semiconductor VECSEL devices and QD laser devices is given. Based on the features of VECSEL devices, the main emphasis is put on the recent development of technological approach on semiconductor QD VECSELs. Then, from the viewpoint of both single QD nanolaser and cavity quantum electrodynamics (QED), a single-QD-cavity system resulting from the strong coupling of QD cavity is presented. In this review, we will cover both fundamental aspects and technological approaches of QD VECSEL devices. Lastly, the presented review here has provided deep insight into useful guideline for the development of QD VECSEL technology, future quantum functional nanophotonic devices and monolithic photonic integrated circuits (MPhICs).

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第2期 pp.157-170      

Chang-Qi MA  

      摘要 + ：(浏览：1233次) | 此论文可免费阅读 (可能需要登录)

This mini-review summarizes the recent achievements of developing conjugated dendritic oligothiophenes (DOT) for use in solution-processed bulk heterojunction (BHJ) solar cells. These DOTs are structurally defined molecules with relatively high molecular weight. Therefore, this novel class of thiophene based material possesses not only some advantages of oligomers, such as defined and monodispersed molecular structure, high chemical purity, but also some characteristics of polymers, for example, good solution-processability. In addition, the step-by-step approach of its synthesis allows precise functionalization of dendritic backbones with desired moieties, which is helpful to finely tune the optical and electronic properties of materials. Power conversion efficiencies (PCE) of BHJ solar cells were achieved up to 2.5% when functionalized thiophene dendrimers were used as electron donor and electron acceptor was a fullerene derivative. These results indicated that dendritic oligothiophenes are a novel class of the materials of electron donor for solution-processed organic solar cells.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2011年第4卷第1期 pp.12-23      

Li LIU   Ze ZHANG  

      摘要 + ：(浏览：1230次) | 此论文可免费阅读 (可能需要登录)

One-dimensional (1D) organic nanoribbons built on N-p-nitrophenylsalicylaldimine cadmium complex were synthesized via a facile solvothermal route. Scanning electron microscope images revealed that the as-synthesized products were ribbon like with widths of 500 nm, thicknesses of about 50 nm, and lengthes up to several hundred micrometers. Fourier transform infrared spectrum was employed to characterize the structure. The conductivity of a bundle of nanoribbons was also measured, which showed that Schiff base cadmium nanoribbons had good photoconductive property. This work might enrich organic photoconductive materials and be applicable in nano photoswitch devices in the future.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2011年第4卷第2期 pp.199-203      

Yi DING   Peifu GU  

      摘要 + ：(浏览：1229次) | 此论文可免费阅读 (可能需要登录)

The energy from a source was rearranged through reflection or refraction by a freeform optical element in order to get the desired uniform illumination. The numerical results of first-order partial differential equation sets had been investigated to obtain the freeform optical element, and the equations could be used to get the characteristics of the light source and the desired illumination. For example, a light emitting diode (LED) with a Lambertian light emitting surface of 1 mm61 mm was applied as the light source. Two kinds of freeform reflectors and one freeform lens were designed for different illuminations, and the simulated uniformity was near to 90%. Considering the size of these freeform optical elements, the illumination system can be very compact and efficient if the freeform optical element is applied in the illumination system of projectors with LED as source.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2008年第1卷第1期 pp.173-177      

Gongli XIAO   Xiang JI   Linfei GAO   Xingjun WANG   Zhiping ZHOU  

      摘要 + ：(浏览：1222次) | 此论文可免费阅读 (可能需要登录)

This study uses a dipole embedded in Al2O3 layer to excite a symmetric surface plasmon polariton (SPP) mode in Au/Al2O3/Au waveguide to investigate its profile properties by using finite-difference time-domain (FDTD) method. The excited dipole decay radiatively direct near-field coupling to SPP mode owing to thin Al2O3 layer of 100 nm. The effects of electric and magnetic field intensity profiles and decay length have been considered and characterized. It is found that dipole location is an important factor to influence the horizontal and vertical profile properties of symmetric SPP mode in Au/Al2O3/Au waveguide. The amplitudes of electric and magnetic field intensity and the wavelengths of metal-insulatormetal (MIM) SPP resonance mode can be tuned by varying dipole location. The horizontal and vertical decay lengths are 19 and 24 nm, respectively. It is expected that the Au/Al2O3/Au waveguide structure is very useful for the practical applications of designing a SPP source.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第1期 pp.63-67      

Liyang LU   Jiayang WU   Tao WANG   Yikai SU  

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We propose and numerically demonstrate an ultrafast real-time ordinary differential equation (ODE) computing unit in optical field based on a silicon microring resonator, operating in the critical coupling region as an optical temporal differentiator. As basic building blocks of a signal processing system, a subtractor and a splitter are included in the proposed structure. This scheme is featured with high speed, compact size and integration on a siliconon- insulator (SOI) wafer. The size of this computing unit is only 35 μm × 45 μm. In this paper, the performance of the proposed structure is theoretically studied and analyzed by numerical simulations.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第1期 pp.99-106      

Jingle LIU   Xi-Cheng ZHANG  

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Terahertz (THz) wave science and technology have been found countless applications in biomedical imaging, security screening, and non-destructive testing as they approach maturity. However, due to the challenge of high ambient moisture absorption, the development of remote open-air broadband THz spectroscopy technology is lagging behind the compelling need that exists in homeland security, astronomy and environmental monitoring. Furthermore, the underlying physical mechanisms behind the interaction between the THz wave and laserinduced plasma which responds strongly to electromagnetic waves have not been fully understood. This review aims to explain the light-plasma interaction at THz frequencies within a semiclassical framework along with experimental study of the femtosecond-laserinduced nitrogen plasma fluorescence under the illumination of single-cycle THz pulses. The results indicate that THz-radiation-enhanced-emission-of-fluorescence (THz- REEF) is dominated by electron kinetics in the THz field and the electron-impact excitation of gas molecules/ions. The information of the time-dependent THz field can be recovered from the measured time-resolved THz-REEF from single-color laser induced plasma with the help of the bias as local oscillator. The calculations and experimental verification lead to complete understanding of the science behind these effects and push forward to extend their capabilities in related applications such as remote THz sensing, plasma diagnostics and ultrafast photoluminescence modulation. Systematic studies in selected gases including neon, argon, krypton, xenon, methane (CH4), ethane (C2H6), propane (C3H8), and n-butane (C4H10) gases were performed to obtain an improved understanding of the THz-REEF. The dependences of the enhanced fluorescence on the THz field, laser excitation intensity, gas pressure, and intrinsic atomic properties were experimentally characterized. Both narrow line emission and broad continuum emission of the gas plasma were enhanced by the THz field. Their fluorescence enhancement ratios and time-resolved enhanced fluorescence were largely dependent on the scattering cross section and ionization potential of atoms. For the first time, we demonstrated a novel ‘all-optical’ technique of broadband THz wave remote sensing by coherently manipulating the fluorescence emission from asymmetrically ionized gas plasma that interacted with THz waves. By studying the ultrafast electron dynamics under the single cycle THz radiation, we found that the fluorescence emission from laser-induced air plasma was highly dependent on the THz electric field and the symmetry of the electron drift velocity distribution created by two-color laser fields. The time-resolved THz-REEF can be tailored by switching the relative two-color phase and laser polarizations. Owing to the high atmospheric transparency and omni-directional emission pattern of fluorescence, this technique can be used to measure THz pulses at standoff distances with minimal water vapor absorption and unlimited directionality for optical signal collection. The coherent THz wave detection at a distance of 10 m had been demonstrated. The combination of this method and previously demonstrated remote THz generation would eventually make remote THz spectroscopy available. We also introduced a unique plasma diagnostic method utilizing the THz-wave-enhanced fluorescence emission from the excited atoms or molecules. The electron relaxation time and plasma density were deduced through applying the electron impact excitation/ionization and electron-ion recombination processes to the measured time-delay-dependent enhanced fluorescence. The electron collision dynamics of nitrogen plasma excited at different gas pressures and laser pulse energies were systematically investigated. This plasma diagnostic method offers picosecond temporal resolution and is capable of omnidirectional optical signal collection. The ultrafast quenching dynamics of laser-pulse-induced photoluminescence in semiconductors under the radiation of single-cycle THz pulses was studied. It was found that the quenching in both cadmium telluride (CdTe) and gallium arsenide (GaAs) was linearly proportional to the intensity of incident THz waves and reaches up to 17% and 4% respectively at the peak intensity of 13 MW/cm2. The THz-wave-induced heating of the carriers and lattice and the subsequent decreased efficiency of photocarrier generation and recombination were most likely to be responsible for the quenching. This is potentially useful for the applications of a non-invasive ultrafast light modulator for photoluminescence devices with picoseconds switching time in the fields of the light-emitting devices and optical communication.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2014年第7卷第2期 pp.156–198      

S. W. Ricky LEE   Rong ZHANG   K. CHEN   Jeffery C. C. LO  

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Currently most light emitting diode (LED) components are made with individual chip packaging technology. The main manufacturing processes follow conventional chip-based IC packaging. In the past several years, there has been an uprising trend in the IC industry to migrate from chip-based packaging to wafer level packaging (WLP). Therefore, there is a need for LEDs to catch up. This paper introduces advanced LED WLP technologies. The contents cover key enabling processes such as preparation of silicon sub-mount wafer, implementation of interconnection, deposition of phosphor, wafer level encapsulation, and their integration. The emphasis is placed on how to achieve high throughput, low cost manufacturing through WLP.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第2期 pp.119-126      

Hussein TALEB   Kambiz ABEDI  

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In this paper, the effects of homogeneous and inhomogeneous broadenings on the response of quantumdot semiconductor optical amplifier (QD-SOAs) are investigated. For the first time, the state space model is used to simulate static and dynamic characteristics of the QD-SOA. It is found that with decreasing the homogeneous and inhomogeneous broadenings, the saturation power of the QD-SOA decreases and the optical gain and the ultrafast gain compression increase. Simulation results show that with decreasing the homogeneous broadening from 20 to 1 meV, the gain compression increases from 40% to 90%, the unsaturated optical gain becomes approximately tripled, and the saturation power becomes two times less. Also, simulations demonstrate that with decreasing the inhomogeneous broadening from 50 to 25 meV, the gain compression increases from less than 50% to more than 90%, the unsaturated optical gain becomes approximately 10-fold, and the saturation power becomes three times less. In addition, it is found that the homogeneous and inhomogeneous linewidths should be small for nonlinear applications. The homogeneous and inhomogeneous broadenings need to be large enough for linear applications.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第4期 pp.445-456      

Weixuan HU   Buwen CHENG   Chunlai XUE   Shaojian SU   Haiyun XUE   Yuhua ZUO   Qiming WANG  

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This paper reviews the recent progress in photonic devices application of Ge-on-Si. Ge-on-Si materials and optical devices are suitable candidates for Si-based optoelectronic integration because of the mature epitaxial technique and the compatibility with Si complementary metal-oxide-semiconductor (CMOS) technology. Recently, the realities of electric-pump Ge light emitting diode (LED) and optical-pump pulse Ge laser, Ge quantum well modulator based on quantum Stark confined effect, waveguide Ge modulator based on Franz-Keldysh (FK) effect, and high performance near-infrared Ge detector, rendered the Si-based optoelectronic integration using Ge photonic devices. Ge-on-Si material is also an important platform to grow other materials on it for Sibased optoelectronic integration. InGaAs and GeSn have been grown on the Ge-on-Si. InGaAs LED and GeSn photodetector have been successfully fabricated as well.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第1期 pp.41-50      

Ming LI   Jose AZANA   Ninghua ZHU   Jianping YAO  

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This paper reviews recent progresses on optical arbitrary waveform generation (AWG) techniques, which could be used to break the speed and bandwidth bottlenecks of electronics technologies for waveform generation. The main enabling techniques for optically generating optical and microwave waveforms are introduced and reviewed in this paper, such as wavelength-to-time mapping techniques, space-to-time mapping techniques, temporal pulse shaping (TPS) system, optoelectronics oscillator (OEO), programmable optical filters, optical differentiator and integrator and versatile electro-optic modulation implementations. The main advantages and challenges of these optical AWG techniques are also discussed.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2014年第7卷第3期 pp.359–375      

Jianji DONG   Yuan YU   Bowen LUO   Dexiu HUANG   Xinliang ZHANG  

      摘要 + ：(浏览：1175次) | 此论文可免费阅读 (可能需要登录)

We propose and experimentally demonstrate two simple solutions for power-efficient ultra-wideband (UWB) radio frequency (RF) system assisted by an electrical bandpass filter (EBPF). In the first solution, any optical Gaussian pulse with enough bandwidth is transmitted over optical fiber link, and then converted to a power-efficient UWB pulse by an EBPF with a passband of 3.1-10.6 GHz. The transmission and modulation of UWB signal is processed in optical domain, whereas the generation of UWB is processed in electrical domain. Both UWB modulations of on-off keying (OOK) and binary phase shift keying (BPSK) are experimentally demonstrated. In the second solution, the EBPF is used to convert any electrical waveform to a power-efficient UWB pulse. Then the electrical UWB pulse is converted to an optical UWB pulse with a Mach-Zehnder modulator (MZM), and then distributed over long haul fiber link. These two solutions embody the advantages of both low-loss longhaul transmission of optical fiber and mature electrical circuits. And the millimeter-wave UWB signal is also demonstrated.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第4期 pp.403-413      

Yaoguang RONG   Guanghui LIU   Heng WANG   Xiong LI   Hongwei HAN  

      摘要 + ：(浏览：1169次) | 此论文可免费阅读 (可能需要登录)

As a low-cost photovoltaic technology, dyesensitized solar cell (DSSC) has attracted widespread attention in the past decade. During its development to commercial application, decreasing the production cost and increasing the device stability take the most importance. Compared with conventional sandwich structure liquid-state DSSCs, monolithic all-solid-state mesoscopic solar cells based on mesoscopic carbon counter electrodes and solid-state electrolytes present much lower production cost and provide a prospect of long-term stability. This review presents the recent progress of materials and achievement for all-solid-state DSSCs. In particular, representative examples are highlighted with the results of our monolithic all-solid-state mesoscopic solar cell devices and modules.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2013年第6卷第4期 pp.359-372      

Jinxin BIAN   Yiming ZHU   Xiaoxuan JIA   Lin CHEN   Yan PENG   Yongcai YANG   Songlin ZHUANG  

      摘要 + ：(浏览：1167次) | 此论文可免费阅读 (可能需要登录)

The absorption spectra from 0.2 to 1.7 THz of five water-acetone mixtures, whose concentrations are 0%, 25%, 50%, 75%, and 100%, has been investigated by THz time-domain spectroscopy (THz-TDS). The result indicates that of acetone solutions with different concentrations have different absorption for THz radiation, which is analyzed and attributed to the variation of the hydrogen bond. Furthermore, we also find the absorption of the water-acetone mixture almost linearly increases with the increase of water concentration in the THz range.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2011年第4卷第4期 pp.444-447      

Yu TIAN   Huiquan CHEN   Xiaolong ZHU   Guang ZHENG   Jiangnan DAI  

      摘要 + ：(浏览：1166次) | 此论文可免费阅读 (可能需要登录)

This paper reported a simple and effective method for fabricating and patterning highly ordered ZnO nanorod arrays on H2-decomposed GaN epilayer via hydrothermal route. The edge of pattern, which has been decomposed by H2 flow, provides appropriate nucleation sites for the selective-growth of aligned ZnO nanorods. The density of ZnO nanorod arrays assembled the hexagonal pattern can be tuned by varying the solution concentrations, growth time and reaction temperatures. The results have demonstrated that the ZnO nanorods are highly uniform in diameter and height with perfect alignment and are epitaxially grown along [0001] direction. This work provides a novel and accessible route to prepare oriented and aligned ZnO nanorod arrays pattern. And the aligned ZnO nanorods form an ideal hexagonal pattern that might be used in many potential applications of ZnO nanomaterials.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2013年第6卷第4期 pp.440-447      

Tuan GUO   Qida ZHAO   Lihui LIU   Guiling HUANG   Lifang XUE   Guoyu LI   Bo LIU   Weigang ZHANG   Guiyun KAI   Shuzhong YUAN   Xiaoyi DONG  

      摘要 + ：(浏览：1148次) | 此论文可免费阅读 (可能需要登录)

Temperature-insensitive fiber Bragg grating (FBG) dynamic pressure sensing based on reflection spectrum bandwidth modulation and differential optical power detection is proposed and experimentally demonstrated. A special double-hole cantilever beam is designed to induce linear strain-gradient distribution along the sensing FBG, resulting in FBG reflection spectrum symmetrical broadening and optical power increase. Based on the theory of optical waveguide and material mechanics, the causation of FBG spectrum broadening under the linear strain-gradient is analyzed, and the corresponding force-to-bandwidth broadening relation and force-to-optical power relation are formulized. FBG spectrum bandwidth and reflection optical power linearly change with applied pressure and both of them are insensitive to spatially uniform temperature variations. For a temperature range from 210uC to 80uC, the measured pressure fluctuates less than 1.8% F.S. (120 kPa) without any temperature compensation. The system acquisition time is up to about 80 Hz for dynamic pressure measurement.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2008年第1卷第1期 pp.113-118      

Diqiu HUANG   Xiangbin ZENG   Yajuan ZHENG   Xiaojin WANG   Yanyan YANG  

      摘要 + ：(浏览：1148次) | 此论文可免费阅读 (可能需要登录)

This paper presents the influence of process parameters, such as argon (Ar) flow rate, sputtering power and substrate temperature on the band gap of Al-doped ZnO film, Al-doped ZnO thin films were fabricated by radio frequency (RF) magnetron sputtering technology and deposited on polyimide and glass substrates. Under different Ar flow rates varied from 30 to 70 sccm, the band gap of thin films were changed from 3.56 to 3.67 eV. As sputtering power ranged from 125 to 200W, the band gap was varied from 3.28 to 3.82 eV; the band gap was between 3.41 and 3.88 eV as substrate temperature increases from 150°C to 300°C. Furthermore, the correlation between carrier concentration and band gap was investigated by HALL. These results demonstrate that the band gap of the Al-doped ZnO thin film can be adjusted by changing the Ar flow rate, sputtering power and substrate temperature, which can improve the performance of semiconductor devices related to Al-doped ZnO thin film.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2013年第6卷第1期 pp.114-121      

Thomas G. BROWN   Amber M. BECKLEY  

      摘要 + ：(浏览：1145次) | 此论文可免费阅读 (可能需要登录)

Spatial inhomogeneities in the polarization of a light field can show fascinating effects in focusing, propagation, illumination, and imaging. This paper provides examples of these effects and describes how deterministic stress on the periphery of an optical element can be used in fundamental studies of beam propagation, as well as applications such as polarimetry.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2013年第6卷第1期 pp.89-96      

Weisong YANG   Yipei WANG   Yaoguang MA   Chao MENG   Xiaoqin WU   Qing YANG  

      摘要 + ：(浏览：1133次) | 此论文可免费阅读 (可能需要登录)

The characteristics of curved semiconductor nanowire (NW) lasers were investigated. The red-shift in the laser spectra with increasing bending angles can be observed much more clearly than that in the photoluminescence (PL) spectra. Due to oscillation of light in resonant cavity, the bending loss of laser exhibits multiple times amplification of that of PL. Furthermore, an abnormal phenomenon of dominant peak switching is found in curved NWs when increasing the pump power, which has been first discovered and reported.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2013年第6卷第4期 pp.448-451      

Jia WANG   Qingyan WANG   Mingqian ZHANG  

      摘要 + ：(浏览：1130次) | 此论文可免费阅读 (可能需要登录)

Scanning near-field optical microscopy (SNOM) is an ideal experimental measuring system in nano-optical measurements and characterizations. Besides microscopy with resolution beyond the diffraction limit, spectroscope with nanometer resolution and other instruments with novel performances have been indispensable for researches in nano-optics and nanophotonics. This paper reviews the developing history of near-field optical (NFO) measuring method and foresees its prospects in future. The development of NFO measurements has gone through four stages, including optical imaging with super resolution, near-field spectroscopy, measurements of nanooptical parameters, and detections of near-field interactions. For every stage, research objectives, technological properties and application fields are discussed.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第2期 pp.171-181      

Libo LI   Qihong LOU   Jun ZHOU   Jingxing DONG   Yunrong WEI   Jinyan LI  

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The output capability of large mode area (LMA) multimode fiber laser depends on the fiber bending. To study the relationship, the output capability of multimode fiber laser was measured under various bending diameters, and it was also theoretically calculated. Measured respectively were the beam quality factor M2, by means of knife edge for the different bending diameters of LMA fiber, and the slope efficiency. When the bending diameters 285, 195 and 130 mm were used, the corresponding beam quality factors were 2.88, 1.82 and 1.67 with the slope efficiency at 39%, 35% and 34%, respectively. In addition, for the LMA multimode fiber used in the experiment, losses of different modes were calculated theoretically under various bending diameters. The experimental results correspond to the calculated results.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2008年第1卷第1期 pp.91-94      

Liang ZHAO   Junqiang SUN   Xinliang ZHANG   Cong CHEN  

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Competition mechanism in multiple four-wave mixing (MFWM) processes is demonstrated theoretically. Provided considering only two waves injected into a highly nonlinear fiber (HNLF), there are three modes displaying comprehensive dynamic behaviors, such as fixed points, periodic motion, and chaotic motion. Especially, Mode C ofMFWM is emphasized by analyzing its phase-space trajectory to demonstrate nonlinear wavewave interactions. The study shows that, when the phasespace trajectory approaches or gets through a saddle point, a dramatic power depletion for the injected wave can be realized, with the representative point moving chaotically, but when phase-space trajectories are distributed around a center point, the power for the injected wave is retained almost invariable, with the representative point moving periodically. Finally, the evolvement of satellite wave over an optical fiber is investigated by comparing it with the interference pattern in Young’s double-slit experiment.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第4期 pp.414-428      

Binbin CHEN   Haobo CHENG   Hon Yuen TAM   Hui LI  

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Electrorheological (ER) finishing utilizes the flow of electrically stiffened abrasive fluid through a preset converging gap formed by the work-piece surface and a moving tool. An ER finishing tool characterized by cathode integrated with anode together is proposed, whose electric field distribution is finite-element-analyzed (FEA) and is useful to finish both conductive work-piece and non-conductive ones. Experiments were performed to finish a K9 glass by this tool. After 30 minutes polishing, the surface roughness was reduced from 8.46 to 2.53 nm Ra which is better than previously reported 2.9 nm. The result verified the validity of the integrated-electrodes tool for non-conductive optical glasses.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2011年第4卷第4期 pp.467-471      

Dagong JIA   Haiwei ZHANG   Zhe JI   Neng BAI   Guifang LI  

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Recently, space-division multiplexing (SDM) techniques using multi-core fiber (MCF) and few-mode fiber (FMF) have been introduced into optical fiber communication to increase transmission capacity. Two main types of optical fiber amplifiers based on the Erbiumdoped fiber (EDF) and the Raman effect have been developed to amplify signals in the MCF and FMF. In this paper, we reviewed the principles and configurations of these amplifiers.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第4期 pp.351-357      

Lingni ZHU   Chunqing GAO   Ran WANG   Mingwei GAO   Xin WANG   Hans Joachim EICHLER  

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This paper report an 1645 nm Er:YAG laser resonantly pumped by an Er-fiber laser operating at 1532 nm. 1.78W continous wave (CW) output power with a slope efficiency of 52% was obtained using a long ring cavity and an 1 at.% doped Er:YAG crystal. In Q-switched mode, the obtained pulse energy was 1.6 mJ at a repetition rate of 500 Hz; for 1 kHz repetition rate, 1.2 mJ output energy was obtained.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第4期 pp.400-402      

Xiaoyan SUN   Peng HUANG   Jiefeng ZHAO   Li WEI   Nan ZHANG   Dengfeng KUANG   Xiaonong ZHU  

      摘要 + ：(浏览：1102次) | 此论文可免费阅读 (可能需要登录)

Long period fiber gratings (LPFGs) with different spectral characteristics were fabricated with 1 kHz, 50 fs laser pulses. The contrast of resonant rejection band can be significantly increased by a proper amount of axial stress along a fiber during laser writing or postprocessing with lower energy density laser irradiation. Variations of focal condition, pulse energy of laser irradiation and the number of grating periods lead to the generation of resonance rejection band of LPFGs from single-peak to multi-peak plus larger out-of-band loss. The out-of-band loss is primarily caused by Mie scattering from the laser processed cites, and it can be reduced by decreasing the duty cycle of grating pitch instead of lowing down the actual power of laser irradiation.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第3期 pp.334-340      

Cunxi CHENG   Jihuai WU   Yaoming XIAO   Yuan CHEN   Haijun YU   Ziying TANG   Jianming LIN   Miaoliang HUANG  

      摘要 + ：(浏览：1090次) | 此论文可免费阅读 (可能需要登录)

Titanium dioxide-double-walled carbon nanotubes (TiO2-DWCNTs) with DWCNTs/TiO2 of 20 wt.% is prepared by a conventional sol-gel method. Doping the TiO2-DWCNTs in TiO2 photoanode, a flexible dyesensitized solar cell (DSSC) is fabricated. The sample is characterized by scanning electron microscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) absorption, ultraviolet-visible spectroscopy (UVvis) absorption spectra，electrochemical impedance spectroscopy (EIS) technique and photovoltaic measurement. It is found that adding a certain amount of TiO2-DWCNTs can efficiently decrease the resistance of charge transport, improve dye adsorption. Under an optimal condition, a flexible DSSC contained with 0.50 wt.% TiO2-DWCNTs achieves a light-to-electric energy conversion efficiency of 3.89% under a simulate solar light irradiation of 100mW.cm-2.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第2期 pp.224-230      

Haibo RAO   Kun DING   Jirong SONG   Likun XIE   Wei WANG   Xianlong WAN   Linsong ZHOU   Junyuan LIAO  

      摘要 + ：(浏览：1086次) | 此论文可免费阅读 (可能需要登录)

Phosphor-converted light-emitting diodes (pc-LEDs), which employ blue LEDs with yellow phosphors to generate white light illumination, is a widely used solidstate lighting source. In order to conduct a phosphor layer coating with high quality on LED chip, a self-adaptive coating technology is introduced in this paper. A slurry coating technique combined with self-exposure method is applied and developed to demonstrate the benefits of selfadaptive coating layer. For self-exposure, the slurry coating is exposed to the blue emission of LED itself other than to ultraviolet (UV) light outside to make photoresist crosslinking. Results of measurement indicate that white LEDs with self-adaptive coating have shown self-adaptability to the angular distribution of intensity of blue light and performed higher spatial color uniformity than those with conventional coating and other conformal coating.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第2期 pp.147-152      

Xue FENG   Fang LIU   Yidong HUANG  

      摘要 + ：(浏览：1085次) | 此论文可免费阅读 (可能需要登录)

Surface plasmon polariton (SPP) is an attractive candidate to improve internal quantum efficiency (QE) of spontaneous emission (SE) from nano-structured silicon (Si) including nano-porous silicon (NP-Si) and silicon nanocrystal (Si-NC). Since the SPP resonant frequency of common metals, e.g., gold (Au), silver (Ag), copper (Cu), and aluminum (Al), is too high, the SPP resonance has to be engineered to match the luminescence from nanostructured Si. For this purpose, we have proposed and demonstrated three approaches including metal-rich Au(1 - α)-SiO2(α) cermet SPP waveguide (WG), compound layer structure WG and metallic grating. In this paper, those approaches are reviewed and discussed. According to the calculated results, such three methods could effectively enhance SE rate from NP-Si or Si-NCs and show potential in developing high efficiency Si based light sources with electric pump.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第1期 pp.51-62      

Huiqi LIAO   Ming TANG   Hailiang ZHANG   Yiwei XIE  

      摘要 + ：(浏览：1076次) | 此论文可免费阅读 (可能需要登录)

This paper proposed and experimentally demonstrated an all-fiber tunable and programmable bandpass filter using a linearly chirped fiber Bragg grating (CFBG). The center wavelength and spacing of the transmission peaks could be independently tuned via computer. The tunable range is about 18 nm. With this filter we demonstrated a tunable fiber ring laser which has an output power of about - 7 dBm, full-width at halfmaximum linewidth of ~0.017 nm which is limited by the resolution of the optical spectrum analyzer (OSA). Furthermore, a spacing tunable dual-wavelength fiber laser was achieved with the same setup. This all-fiber laser features advantages like simple structure, low cost, flexible and digital tuning capability.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2013年第6卷第4期 pp.468-471      

Shuxin LI   Yunjun RUI   Yunqing CAO   Jun XU   Kunji CHEN  

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A series of Si-rich amorphous silicon carbide (a-SiC:H) thin films were deposited in conventional plasma enhanced chemical vapor deposition system with various gas ratio R = [CH4]/[SiH4]. The microstructural, optical and electronic properties of as-deposited films were investigated in this study. It was found that optical band gap was linearly proportional to carbon content in the films and it could be controlled in a range of 1.8-2.4 eV by changing the gas ratio, R. Both dark and photo conductivities in room temperature were decreased with the increasing of carbon content in the films, and the photosensitivity reached as high as 104 for the film with the optical band gap of 1.96 eV. The as-deposited samples were subsequently annealed at the temperatures of 900°C and 1000°C. The formation of nanocrystalline silicon (nc-Si) dots in amorphous silicon carbide (a-SiC) host matrix was shown. The dark conductivity was enhanced by five orders of magnitude after annealing compared with that of as-deposited films. The result of temperature-dependent conductivity suggested that the property of carrier transport was dominated by conduction process between the extended states. Furthermore, room temperature electroluminescence (EL) was achieved from nc-Si/SiC system and the possible mechanism of radiative recombination mechanism was discussed.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第1期 pp.107-111      

Li JIANG   Aimiao QIN   Kunpeng JIANG   Lei LIAO   Xiulan WU   Chaojian WU  

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Hydrophilic photoluminescent CdTe/poly (1, 4-butanediol-citrate) (PBC) bioelastomer nanocomposite was successfully synthesized by a two-step method and characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Uv-vis spectroscopy, photoluminescence (PL) spectroscopy and scanning electron microscope (SEM). The differential scanning calorimetry analysis shows that the bioelastomer nanocomposites with different mass fractions of CdTe have low glass-transition temperature, which indicates that they possess elastic property in the range from room temperature to the expected applied temperature (37°C). The measurements of the hydrophilicity, in vitro degradation and PL show that the nanocomposite has good hydrophilicity, degradation and high fluorescence properties.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2013年第6卷第4期 pp.452-457      

Wei CHEN   Hanmin YAO   Fan WU   Shibin WU   Qiang CHEN  

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To ensure the safe and normal operation of the whole optical system, it is important to test and evaluate the quality of optical components. The article explores the advantages and disadvantages of general parameters used in aspheric surface testing, the composition of the system, the principle of operation and the design of related power spectral density (PSD) software used in testing large aspheric surfaces with Shack-Hartmann and phase shifting interferometer. The results indicate that PSD can give the spatial frequency distribution of the wavefront aberration when large aperture phase shifting interferometer is used as an instrument to test the wavefront, and this can also be applied as an evaluation standard in testing the quality of optical components. In addition, this paper describes the test results of optical components in the size of 64 mm×64 mm.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2008年第1卷第1期 pp.197-200      

Baozeng LI   Anting WANG   Hai GUO   Xuesheng CHEN   Hua JIANG   Zhiqiang ZHENG   Hai MING  

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The up-conversion luminescence of Er3+ and Er3+/Yb3+ ions doped in lanthanum-modified lead zirconate titanate (PLZT) under 980 nm excitation at room temperature has been investigated. The green upconversion luminescence at 540 and 566 nm was observed in Er3+:PLZT; the greater the concentration of Er3+ ions, the stronger the intensity. In Er3+-Yb3+: PLZT, other than the green up-conversion luminescence at 540 and 566 nm, a relatively weak red up-conversion luminescence at 668 nm was also observed. Both green and red up-conversion luminescence intensities presented an approximately quadratic dependence on excitation power, which indicated that two excitation photons are involved in the up-conversion process of Er3+:PLZT and Er3+-Yb3+:PLZT. The characteristics of PLZT ceramic material were also studied by Raman spectroscopy. This work shows a promising future for developing multifunctional up-conversion electrooptical devices using Er3+ and Er3+/Yb3+ ions doped PLZT.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2008年第1卷第1期 pp.142-146      

Xia GUO   Xinxin LUAN   Wenjuan WANG   Chunwei GUO   Guangdi SHEN  

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Scalabilities of light-emitting diodes (LEDs) and vertical-cavity surface-emitting lasers (VCSELs) with tunnel-regenerated multi-active-region (TRMAR) structure were investigated. It was found that the output optical power and quantum efficiency of these new LEDs with TRMAR increased with the number of its active regions, but the threshold gain and threshold current density decreased. However, for VCSELs with TRMAR, the differential quantum efficiency and optical power increased with the number of the active region. The results suggest that LEDs and VCSELs with the TRMAR structure have some potential advantages over the conventional LEDs or VCSELs in high internal quantum efficiency, low heat generation, high round-trip gain, and so on. These advantages will make TRMAR LEDs or VCSELs more attractive for the industrial application.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2013年第6卷第1期 pp.97-101      

Duan LIU   Songnian FU   Ming TANG   Ping SHUM   Deming LIU  

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This paper investigated the impact of Rayleigh backscattering (RB) noise in the proposed wavelengthdivision-multiplexed (WDM) single-fiber loopback access network. RB noise’s impacts on the downstream and upstream service were discussed in details. It was found that the receiver sensitivity was less sensitive when the seeding-light power was below - 12.6 dBm. And for the uplink RB noise, a higher reflective semiconductor optical amplifier (RSOA)’s bias current results in lower receiver sensitivity.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第4期 pp.435-438      

Yijie HUO   Hai LIN   Robert CHEN   Yiwen RONG   Theodore I. KAMINS   James S. HARRIS  

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Germanium (Ge) has gained much interest due to the potential of becoming a direct band gap material and an efficient light source for the future complementary metal-oxide-semiconductor (CMOS) compatible photonic integrated circuits. In this paper, highly biaxial tensile strained Ge quantum wells (QWs) and quantum dots (QDs) grown by molecular beam epitaxy are presented. Through relaxed step-graded InGaAs buffer layers with a larger lattice constant, up to 2.3% tensile-strained Ge QWs as well as up to 2.46% tensile-strained Ge QDs are obtained. Characterizations show the good material quality as well as low threading dislocation density. A strong increase of photoluminescence (PL) with highly tensile strained Ge layers at low temperature suggests the existence of a direct band gap semiconductor.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第1期 pp.112-116      

Sei-Min KIM   Seon-Ho JANG   Ja-Soon JANG  

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This work demonstrates high-performance and current crowding-free InGaN/GaN light-emitting diodes (LEDs) using an electrically-reverse-connected Schottky diode (SD) and an Mg-delta (δ) doped layer. Possible mechanism of carrier transport at the interface between transparent conducting electrode (TCE) and p-GaN with the δ-doped layer is also investigated. Results show that the LED with the SD and Mg delta (δ)-doping layer yields lower series resistance, higher output power, and lower reverse leakage current compared to normal LEDs. In addition, unlike the normal LED, there is no occurrence for the current crowding effect in the proposed LED even at high current density of 380 mA/cm2. These remarkable behaviours clearly indicate that the use of the SD and δ-doping in the p-GaN region is very promising to achieve high-brightness and excellent-reliability GaN-based LEDs.

       PDF全文 (下载：0)        Frontiers of Optoelectronics ，2012年第5卷第2期 pp.127-132