Abstract:On the start occasion of the New Year, 2010, we would like to extendour sincere appreciations and compliments to all readers, authors,reviewers, all the members of the editorial board of Optoelectronics

Abstract:A theoretical model in the 1900 nm waveband for amplified spontaneous emission (ASE) of thulium-doped silica fiber is presented. The ASE spectral power as functions of the fiber length and the pump power is investigated by solving the rate and propagation equations. By calculation, when the concentration of thulium in fiber is 2.25×1025 m-3, the fiber core diameter is 2.6 μm, and the pump power is 200 mW at 808 nm, the optimal fiber length is 8.1 m, and the output power of ASE can reach 60 mW in the range o...

Abstract:The goal of Optoelectronics Letters is to rapidly report original,new and important results in the fields of photonics and optoelec-tronics in English,

Abstract:Rod-like gold nanoparticles can be formed from HAuCl4 aqueous solution with ultraviolet (UV) irradiation in the absence of templates, avoiding possible poisonous surfactant embedded into the surface of functional gold nanoparticles applied in biomedicine. The aspect ratio of nanorods ranges from 1.1 to 4.4 with the concentration of HAuCl4 0.2 mM, which can be verified by HRTEM images and the absorption spectrum. It is found that the nanocluster with several atoms occurs prior to the formation of nanorods, h...

Abstract:Nanocrystalline undoped and nickel doped zinc oxide (Zn1-xNixO, x=0.00, 0.01) powders are successfully synthesized by a simple and low-temperature auto-combustion method. The microstructural and optical absorption and emission properties of the as-prepared samples are obtained using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infra-red spectrometer (FTIR), UV-visible and photoluminescence (PL). The structure study confirms the formation of the hexagonal wurtzite ZnO withou...

Abstract:By analyzing the main recombination mechanisms in GaInAsSb materials, the dependences of the dark current density and open circuit voltage in n+-p GaInAsSb thermophotovoltaic cells on the recombination parameters, carrier concentration and cell thickness are calculated. The results show that the dark current mainly comes from p-region, and it is related with the surface and Auger recombinations in low and high carrier concentration ranges, respectively. The surface and Auger recombinations can be suppressed...

Abstract:A wedge shape Si LED is designed and fabricated with 0.35 μm double-grating standard CMOS technology. The device structure is based on the N-well-P⁺ junction. The P⁺ has a wedge shape and is surrounded by the N-well. The micrographs of Si LEDs’ emitting and layout are captured. The I–V characteristic and spectra of the Si LED are tested. Under room temperature and backward bias, its radiant luminosity is 12 nW at 100 mA, and the wavelength of the emitting peak is located at 764 nm.

Abstract:A design of laser-diode array (LDA) end-pumped Nd:YVO4 laser that generates simultaneously wavelengths of 1064 nm and 1342 nm is presented, and by using type-I critical phase matching (CPM) of BiB3O6, 593.5 nm continuous-wave (CW) laser is obtained with intracavity sum-frequency mixing. The maximum laser output power can reach 3.63 W with the pump power of 27.5 W. The optical-to-optical conversion efficiency is up to 13.2%, which is the highest value at 593.5 nm by the intracavity sum-frequency Nd:YVO4 lase...

Abstract:Three kinds of 650 nm AlGaInP resonant cavity light-emitting diodes (RCLEDs) are fabricated by metal organic chemical vapor deposition (MOCVD) with different numbers of pairs of top distributed Bragg reflectors (DBRs), which are 15, 10 and 5, respectively. By comparing the full width at half maximum (FWHM), light power and the angular far-field emission of the devices, the device with 15 pairs of top DBRs shows the best performance. Its FWHM is 13.4 nm and the light power is 0.63 mW at a driving current of ...

Abstract:An ultra-high speed 1:2 demultiplexer for optical fiber communication systems is designed utilizing the IHP 0.25 μm SiGe BiCMOS technology. The latch of the demultiplexer core circuit is researched. Based on the current measurement condition, a high-gain and wide-bandwidth clock buffer is designed to drive large load. Transmission line theory for ultra-high speed circuits is used to design matching network to solve the matching problem among the input, output and internal signals. The transient analysis shows that this demultiplexer can demultiplex one 100 Gb/s input into two 50 Gb/s outputs. The chip area of it is 0.7 mm × 0.47 mm, the input and output data are both at 400 mV_P-P PCML standard voltage level, and the power consumption of the IC is 900 mW at the power supply of ?4 V.

Abstract:The ultimate detection performance of HgCdTe, quantum well (QW) and extrinsic Si detectors under low temperatures is analyzed. The theoretical limits of the internal photon response for the three detectors are compared. The materials of space-based detectors in space tracking and surveillance system (STSS) are discussed. The results show that among three detectors, the best performance can be obtained from HgCdTe detectors under 40 K in the mid-long wave infrared (MLWIR) and long wave infrared (LWIR) spectr...

Abstract:The influence of temperature and Ga composition on Auger recombination lifetime in n-type and p-type In1-xGaxAs materials is investigated through the simulation, assuming the concentrations of electrons and holes are 1017 cm-3 and 1018 cm-3, respectively. The results show that the temperature has little influence on Auger recombination lifetime of In1-xGaxAs materials at x<0.3. However, it has a great impact when x>0.3 and the effect is more obvious at a lower temperature. Moreover, Auger recombination life...

Abstract:The near-ultraviolet (n-UV) excited blue-emitting Sr2MgSi2O7:Eu2+ phosphors are used for fluorescence lamp and tricolor white LEDs. The effect of nitrogen-doped on the structure of the host and the enhancement of photoluminescence is experimentally investigated. The results show that as the amount of nitrogen-doped varies from 0 to 0.6 (at.), the luminous intensity is found to be increased to 169%, and the partial replacement of O by N results in a change of the crystal field by modifying the symmetry of th...

Abstract:Cr-doped ZnO thin films are prepared on glass substrates by the magnetron sputtering technique. An X-ray diffraction (XRD) is used to analyze the structural properties of the thin films. It indicates that all the thin films have a preferential c-axis orientation. The peak position of the (002) plane shifts to the higher 2θ value, and the peak intensity decreases with the increase of Cr doping. The results of the scanning electron microscopy (SEM) show that the surface morphology becomes loose with the increase of Cr doping. Besides, it is found from the photoluminescence (PL) measurement at room temperature that the ultraviolet emission peak and green emission band are located at 375 nm and 520 nm, respectively, and both intensities of them decrease with the increase of the Cr doping concentration, while the band gap of the ultraviolet emission shifts to the lower wavelength. The experimental results confirm that the optimal Cr doping concentration is 2 at. %.

Abstract:A model of quasi-CPA (chirped pulse amplification) system, in which the input is the transform-limited Gaussian pulses, is set up numerically to investigate the impact of the second order dispersion on the adaptive compensation of self-phase modulation (SPM) effect. The adaptive phase pre-shaping controlled by differential evolution algorithm is introduced to the input pulse before amplification and recompression. With maximizing the peak power of the output pulse, the simulation results show that the norma...

Abstract:A theoretical model in the 1900 nm waveband for amplified spontaneous emission (ASE) of thulium-doped silica fiber is presented. The ASE spectral power as functions of the fiber length and the pump power is investigated by solving the rate and propagation equations. By calculation, when the concentration of thulium in fiber is 2.25 × 10²⁵ m^?3, the fiber core diameter is 2.6 μm, and the pump power is 200 mW at 808 nm, the optimal fiber length is 8.1 m, and the output power of ASE can reach 60 mW in the range of 1800–1950 nm with this fiber length. The optical-to-optical conversion is 30.3%. The optimal pump power also can be obtained by this model.

Abstract:A new grating structure with cladding etched as the sinusoidal function along the length direction is introduced. The cladding area of the grating varies as the sinusoidal function along fiber axes. The coupled mode theory is used to analyze its performance. Compared with the linearly chirped grating, the new structure exhibits an ideal box spectrum with steep edges when the tension is applied on the gratings in two different ways. For the type B grating, without tension after writing, it has a bigger bandw...

Abstract:The phase estimation based on M-th power algorithm is employed in a differential quadrature phase-shift keying (DQPSK) coherent optical fiber communication system, and the system performance improvement is investigated through numerical simulations. It is found that the application of phase estimation algorithm can restrain the phase noise induced by laser linewidth and fiber nonlinear effects, and recover the carrier phase, so the transmission distance of a 40 Gb/s DQPSK-RZ system can be extended to more t...

Abstract:In order to obtain the three dimensional (3D) fluorescence spectra directly and rapidly by in situ and in vivo phytoplankton monitoring, a prototype ocean lidar system with the ability of measuring 3D fluorescence spectra is developed, in which an optical parametric oscillator (OPO) and a grating spectrometer are employed. Using the system, the 3D fluorescence spectra of five typical red-tide species in the East China Sea are measured in lab. The preliminary experimental results show the feasibility of moni...

Abstract:The security of the symmetric probabilistic encryption scheme based on chaotic attractors of neural networks is analyzed and discussed. Firstly, the key uniqueness is proved by analyzing the rotation transform matrix to avoid the attack of the equivalent key. Secondly, the distributed uniformity of the numbers 0 and 1 in the corresponding attracting domain for every chaotic attractor is analyzed by the statistics method. It is testified that the distributed uniformity can be kept if the synaptic matrix of t...

Abstract:Due to the features of the multi-spectral images, the result with the usual methods based on the support vector machine (SVM) and binary tree is not satisfactory. In this paper, a fuzzy SVM multi-class classifier with the binary tree is proposed for the classification of multi-spectral images. The experiment is conducted on a multi-spectral image with 6 bands which contains three classes of terrains. The experimental results show that this method can improve the segmentation accuracy.

Abstract:According to the dipole transition selection rules and by choosing proper transition channels, it is found that the inverted Y-type four-level scheme can be classified into nine different 2nd-order subschemes when using corresponding laser fields, and they can be further classified into eighty 3rd-order subschemes in detail according to different exciting intensities that are applied in different channels. In this paper, the structure multiformity of inverted Y-type four-level scheme is discussed and the de...

Abstract:The spectral density of the quasi-homogeneous (QH) light has been known when it scatters on QH media or propagates in free space. The case that QH sources are surrounded by QH media is proposed in this paper. Under the paraxial approximation, the spectral density of the QH light propagating through QH media is derived. A modified scaling law for the propagation of the QH light through QH media is also obtained. This law also holds true in the far field beyond the paraxial approximation.

Abstract:The fractional Fourier transform (FRFT) is applied to treat the propagation of annular flat-topped beams. Based on the definition of FRFT in the cylindrical coordinate system, analytical formulae are derived for annular flat-topped beams through the FRFT optical systems. By using the formulae, the properties of annular flat-topped beams in the FRFT plane are illustrated numerically. The results show that the intensity distribution properties in the FRFT plane are closely related to the fractional order of t...

Abstract:The microscopic mechanism of low level laser irradiation (LLLI) mending rheology for blood is analyzed by the quantum theory. The results show that the laser can resolve the fibrin clot, so the property of blood rheology is improved, and some bonds of the cholesterol in blood are fractured by the low level laser (LLL). Hence the ratio of membrane cholesterol to membrane phosphatide of the red cell is reduced, and then the blood circulation can be improved. The clinical cured tests and some correlative test ...