Abstract:A carbon nanotube-based(CNT) sensing element is presented, which consists of substrate, insulating layer, electrodes,carbon nanotube and measuring circuit. The sensing components are a single or array of CNTs, which are located on the two electrodes. The CNT-based sensing element is fabricated by CVD (chemical vapor deposition)-direct-growth on microelectrodes. The sensing model and measurement method of electromechanical property are also presented. Finally, the voltage-current characteristics are measured, which show that the CNT-based sensing element has good electrical properties.

Abstract:A novel silicon light emitting device was realized with standard 0.35 μ m 2P4M Mixed Mode/RF CMOS technology. The device functions in a reverse breakdown mode and can be turned on at 8.3 V and operated normally at a wide voltage range of 8.3 V-12.0 V. An output optical power of 13.6 nW was measured at the bias of 10 V and 100 mA, and the emitted light intensity was calculated to be more than 1 mW/cm2. The optical spectrum of the device is in the range of 500-820 nm.

Abstract:The X-ray low angle reflectivity measurement is used to investigate single and bilayer films to determine the parameters ofnanometer-scale structures,three effectual methods are presented by using X-ray reflectivity analysis to provide an accurateestimation of the nanometer film structures. The parameters of tungsten (W) single layer, such as the material density,interface roughness and deposition rate, were obtained easily and speedily. The base metal layer was introduced to measurethe profiles of single low Z material film. A 0.3 nm chromium (Cr) film was also studied by low angle reflectivity analysis.

Abstract:We proposed a called "nano-fabrication based on MEMS technology" approach to realize the typical nano-electromechanical structures,such as integrated nano probe,ultrathin cantilever,silicon nano wire,and doubly clamped nano beam,to demonstrate the feasibility and advantages. We also introduced the characterization of nano structures based on laser vibrometer and piezoresistive effect,the latter method was first time applied to investigate a doubly daped nanobeam with a thickness of about 200 nm.

Abstract:An unique mask moving method is developed for forming effective micro-optical structures with continuous profile. The mechanism for forming different micro-optical profiles is disclosed, and the designed approach for binary moving mask is described. Finally some concrete micro-optical components with typical microstructures are presented for demonstrating the validity of the method.

Abstract:We fabricate a series of samples and OLEDs with organic multilayer quantum well structure, which consist of alternate PBD and Alq3. Both PBD and Alq3 are electron-transporting materials, and PBD is used as potential barrier layer, while Alq3 is used as potential well layer and emitting layer. Compared with double-layer structure, the luminescent characteristics of organic samples and diodes with quantum well structure are investigated and the quantum well structure helps the energy transfer between well layer and barrier layer. The quantum well structure makes carriers disperse in the different well layers and then increases the number of excitons to enhance the efficiency of the recombination.

Abstract:In this paper a preliminary investigation of a novel optoelectronic polymer, poly (p-phenylene N-4-n-butylphenyl-N,N-bis-4-vinylenephenylamine) (PNB), is reported. A single layer structure of ITO/PNB/Al was prepared via spin-coating of PNB solution as a thin film on the top of an ITO substrate, while aluminum top electrode was vacuum evaporated. Dark currentvoltage characteristics of this device showed a typical rectifying behaviour. Photovoltaic response under a monochromatic illumination at 420 nm was observed, with an open circuit voltage of 0.3 V and fill factor of 0.21. Spectral response and optical absorption were found to be matched well. It was also discovered that the device showed a green electroluminescent emission at a forward bias. Turn-on voltage of the device was about 6 V and light output about 22.6 nW at a forward bias of 10 V. The work demonstrated that the PNB material might possess dual exciton sites resulting in a competition for excitons to be either separated or recombined. Both effects were associated with each other, which limited the photovoltaic or electroluminescence to some degrees.

Abstract:A novel all-fiber self-organization coherent Erbium-doped fiber laser is proposed and demonstrated. The laser system is composed of two independent lasers. When each of the two branch lasers operates independently, the output power is 10.41 mW and 8.69 mW respectively. By adjusting a polarization controller (PC), the two lasers achieve coherent coupling,and the output power is 24.4 mW, which is more than two times that the single laser yields. Furthermore, we bring forward and discuss the factor estimating the effect of coherent combination-coherent coupling factor. The value of growth factor to evaluate the effect of coherent combining is 1.27. The coherent fiber laser has the advantages of simple structure, high efficiency and single frequency, which conduce to coherent coupling easily.

Abstract:A novel transmitter to generate a dark RZ signal with tunable duty cycle and extinction ratio is proposed, by modifying the process of precoding, modulating and coding. A dark RZ signal is generated simply by using one dual-arm Mach-Zehnder LiNbO3 modulator. We demonstrate experimentally that this optical dark RZ signal can be directly measured by a conventional binary intensity modulation direct detection (IM-DD) receiver. When different values of duty cycles at 2.5 Gbit/s are adjusted, the experimental results show different BER curves and eye diagrams of the optical dark RZ signal.

Abstract:The characteristics of chirped and phase-shifted fiber Bragg gratings have been investigated by the use of transfer matrix formulation. While the characteristics of a chirped and phase-shifted fiber Bragg grating are the same as those of nonchirped one in some important aspects, both the reflection and transmission windows of a chirped and phase-shifted fiber Bragg grating can be broadened in a wide range. Therefore, chirped and phase-shifted fiber Bragg gratings will have applications in WDM or DWDM optical communication systems. The work in this paper can be used to design the new devices based on chirped and phase-shifted fiber Bragg gratings.

Abstract:This letter addresses several key issues in the process of model-based optical metrology, including three dimensional (3D) sensing, calibration, registration and fusion of range images, geometric representation, and visualization of reconstructed 3D model by taking into account the shape measurement of 3D complex structures,and some experimental results are presented.

Abstract:An optical readout uncooled infrared (IR) imaging detector of bimaterial cantilever array using knife-edge filter operation(KEFO) is demonstrated. The angle change of each cantilever in a focal plane array (FPA) can be simultaneously detected with a resolution of 10-5 degree. A deformation magnifying substrate-free micro-cantilever unit with multi-fold interval metallized legs is specially designed and modeled. A FPA with 160× 160 pixels is fabricated and thermal images with noise equivalent temperature difference (NETD) of 400 mK are obtained by this imaging detector.

Abstract:A novel microscopic interferometry with ability of frequency-variation and phase-shifting is proposed for microstructures testing. By using acousto-optic technique, sequential carriers can be generated with different spatial frequencies so that the temporal phase unwrapping method can be applied for decoding the height information. Combined with phase-shifting technique realized by spatial light modulator, this method is especially suitable for interferometric measurement with high precision and large dynamic range.

Abstract:An experimental investigation on the residual stress in porous silicon micro-structure by means of micro-Raman spectroscopy is presented. It is shown by detecting the Raman peak shifts on the surfaces and cross-sections of electrochemical etched porous silicon samples with different porosities that serious residual stresses distribute complicatedly within the whole porous silicon structure. It is proved that micro-Raman spectroscopy is an effective method for residual stress testing on the micro-structures applied in optoelectronics and microelectronics.

Abstract:Influences of tip radius and sampling interval on applying atomic force microscopy(AFM)in quantitative surface evaluations are investigated by numerical simulations and experiments. Several evaluation parameters of surfaces ranging from amplitude to functional parameters are studied. Numerical and experimental results are in good agreements. The accuracy of estimating tip radius on random rough surface with Gaussian distribution of heights using a blind reconstruction method is also discussed theoretically. It is found that the accuracy is greatly depending on the ratio of actual tip radius to rootmean-square (rms) radius of curvature. To obtain an accurate estimation of tip radius under Gaussian rough surface, the ratio has to be larger than 3/2.

Abstract:Double-wavelength recording used in a pulsed digital micro-holographic system to record ultra-fast processing of the order of femto-second is reported for the first time, where a BBO crystal is used to generate harmonic wave of the incident laser wave, and both of the basic and the frequency doubled waves are time-delayed and introduced to a Michelson's interferom eter to record two sub-holograms with different spatial frequencies on a single frame of a CCD. In the experiment, an ultra fast dynamic process of air ionization induced by a single femto-second laser pulse is recorded with holography by this system, and both of intensity and phase difference images digitally reconstructed are obtained through Fourier transformation and digital filtering, which show clearly the dynamic process of formation and propagation of the plasma, with a time resolution of the order of femto-second.

Abstract:In this paper we report on recent development in the areas of optical vortices generated by micro-optical elements and applications of optical vortices, including optical manipulation, radial polarization and secure free space optical communication

Abstract:Ultra-precision machining is an effective approach to achieve high dimension accuracy and surface finish required in optical and laser components. An extensive study using a two-axis diamond turning machine is conducted to machine the reflector arrays used for laser diode beam shaping. To position the workpiece precisely, theoretical analysis is made so that the dimensional accuracy can be achieved. Investigations into machining burr reduction are carried out. With the process developed, reflectors with optical surface finish of 8 nm in Ra and minimized burr size of less than 0.5 μm have been achieved.

Abstract:School of Computer and Communication, Hunan University, Changsha 410082, ChinaThe photonic band gap structure of 1D photonic crystal with a negative index medium defect layer is studied by using the transfer matrix method. Investigations show that the introdution of negative index medium defect layer and the increase of the negative index value will result in an extension of the band gap. Moreover, by increasing the negative index, the width of defect layer and the numbers of period photonic crystal, the width of defect modes will be narrowed, which is advantaged to obtain optical filters with narrow band. Finally, the effects of absorption on the properties of band gap and on defect modes have been discussed.

Abstract:Some experimental investigations were carried out with the samples of metal A1 and AlCl3 solutions. It is found that the spectrum varies with the change of experimental setup parameters both in Al bulk material and A1C13 solutions. The temporal evolution properties and the affection of incident laser energy on the laser-induced breakdown spectroscopy(LIBS) signals were also discussed. The lifetime of laser induced plasma in A1C13 solutions is found to be about 30 ns which is much shorter than in solid materials. Compared with the solid samples, the Al LIBS signals in A1C13 solutions require higher laser energy. Under the optimized conditions, the detection limit of Al in AlCl3 solution was determined to be around 1000 ppm for the system we used.

Abstract:Theoretical investigation of the phase-matching properties for the tunable coherent terahertz wave generation in the isotropic semiconductor nonlinear materials of CdTe and GaP is presented according to their optical dispersion properties, based on a pulsed dual-wavelength KTP-OPO operating near degenerate point in the process of the difference frequency mixing.The cross-Reststrahlen band dispersion compensation phase-matching technique involved in this interaction is introduced concisely. The optimum lengths of DFG crystals are decided according to the minimum coherence lengths of the crystals in the given pump wavelength ranges. The results of analysis and calculation provide the useful and necessary theoretical basis and guidance for the future experiments.

Abstract:We present a time-resolved two-photon excitation fluorescence spectroscopy and a simultaneous time- and spectrumresolved multifocal multiphoton microscopy system that is based on a high repetition rate picosecond streak camera for providing time- and spectrum- resolved measurement and imaging in biomedicine. The performance of the system is tested and characterized by the fluorescence spectrum and lifetime analysis of several standard fluorescent dyes and their mixtures.Spectrum-resolved fluorescence lifetime images of fluorescence beads are obtained. Potential applications of the system include clinical diagnostics and cell biology etc.

Abstract:The purpose of Optoelectronics Letters is rapid reporting new important results in the fields of photonics-optoelectronics in English to advance the international academic exchanges.

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