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A novel systematic technological process for ZnO-thin-film transistors (TFTs) fabrication was developed which turned out to achieve near-zero threshold voltage devices with good performance and stability. A deuterium implantation method was realised as well to fabricate depletion n-type ZnO TFTs. The inverters based on enhancement/depletion ZnO TFTs reached nearly full swing (0.01-5 V at 5 V VDD) and pretty large noise margin (VNML = 1.01 and VNMH = 3.61 V). Moreover, a transparent radio-frequency identification (RFID) tag chip based on ZnO TFTs was developed. This tag with an anti-collision algorithm for ISO-14443 type-A was first realised under 5 μm ZnO-TFT technology. The proposed RFID tag exhibits ultra-low-power dissipation of

The optical losses of asymmetric and symmetric waveguide structures were calculated theoretically for high power 980 nm diode lasers, by means of the continuity equation under strong injection and the Helmholtz equation of complex refractive index model. The epitaxial materials of the both waveguide structures were prepared by the metallorganic chemical vapor deposition growth technique, and corresponding laser devices were fabricated. The electro-optical performances of both devices were measured and analyzed by comparison. The theoretical calculations and experimental results indicates that, the asymmetric waveguide structure material does not reduce the optical loss, but decreases the series resistance of the diode, therefore, it reduces the joule heating, and enhances the conversion ef

为了实现激光二极管阵列(LDA)的高亮度光纤耦合输出,设计了一套简单有效的光束整形系统.首先采用快慢轴准直透镜压缩LDA的发散角,然后采用双平行平面反射镜光束整形装置,将压缩后的LDA慢轴方向的光束分为4束(也可以根据需要分为任意多束),并将4束子光束在快轴方向重新排列,最后通过聚焦系统,将整形后的光束耦合进入芯径600 μm,数值孔径0.37的光纤.实验测得双平行平面反射镜整形装置的效率为98.87%,系统的整体效率为77.2%.该整形系统设计简单,效牢高,具有很高的应用价值.

Due to the zero dispersion point at 1.3-mu m in optical fibres, 1.3-mu m InGaAsP/InP laser diodes have become main light sources in fibre communication systems recently. In fluences of quantum noises on direct-modulated properties of single-mode 1.3-mu m InGaAsP/InP laser diodes are investigated in this article. Considering the carrier and photon noises and the cross-correlation between the two noises, the power spectrum of the photon density and the signal-to-noise ratio (SNR) of the direct-modulated single-mode laser system are calculated using the linear approximation method. We find that the stochastic resonance (SR) always appears in the dependence of the SNR on the bias current density, and is strongly affected by the cross-correlation coeffcient between the carrier and photon noises, the frequency of modulation signal, and the photon lifetime in the laser cavity. Hence, it is promising to use the SR mechanism to enhance the SNR of direct-modulated InGaAsP/InP laser diodes and improve the quality of optical fibre communication systems.

In order to improve the output power and increase the lifetime of laser diodes, expansion-matched submounts were investigated by finite element analysis. The submount was designed as sandwiched structure. By varying the vertical structure and material of the middle layer, the thermal expansion behavior on the mounting surface was simulated to obtain the expansion-matched design. In addition, the thermal performance of laser diodes packaged by different submounts was compared. The numerical results showed that, changing the thickness ratio of surface copper to middle layer will lead the stress and junction temperature to the opposite direction. Thus compromise needs to be made in the design of the vertical structure. In addition, the silicon carbide (SiC) is the most promising material candidate for the middle layer among the materials discussed in this paper. The simulated results were aimed at providing guidance for the optimal design of sandwich-structure submounts.

We report a new technique, called SAP, for side pumping of double-clad, rare-earth-doped fiber lasers using fiber-coupled pump sources. The highest coupling efficiency can even exceed 92% in theory with this structure.

A novel high-efficiency cooling mini-channel heat-sink structure has been designed to meet the package technology demands of high power density laser diode array stacks.Thermal and water flowing characteristics have been simulated using the Ansys-Fluent software.Owing to the increased effective cooling area, this mini-channel heat-sink structure has a better cooling effect when compared with the traditional macro-channel heat-sinks.Owing to the lower flow velocity in this novel high efficient cooling structure, the chillers' water-pressure requirement is reduced.Meanwhile, the machining process of this high-efficiency cooling mini-channel heat-sink structure is simple and the cost is relatively low, it also has advantages in terms of high durability and long lifetime.This heat-sink is an ideal choice for the package of high power density laser diode array stacks.

Design of the typical laser diode side-pumped Nd:YAG rod system has been discussed using the conventional ray tracing method in this paper. Firstly introduce two basic matrices, refractional and translational matrix, described the transmission of nonparaxial light ray in the medium without concerning the absorption of light. And then, using those matrices, analyze the distribution of pump light in the crystal respectively under the condition of directly pumped system and indirectly pumped system with a cylindrical quartz rod as focusing lens. From the result of simulation, we compare the advantage and disadvantage of the two pumped method, and mainly consider how to select the diameter of the focus lens and cooling tube, indicate the effect of deionized water and cooling tube have on the pump light distribution in the active material. At last, make some conclusions about the side-pumped Nd:YAG laser system.

To obtain a high-power and efficient single-mode laser, a new laser called the slab coupled optical waveguide laser (SCOWL) has been developed. We have simulated its structure and grown the chip with this structure by low-pressure metal organic chemical vapor deposition. We have also produced the broad-area SCOWL and compared it with the traditional structure laser in terms of some performances. This work lays the foundation for further research of ridged lasers with the same structure.

A physical and explicit surface potential model for undoped symmetric double-gate polysilicon thin-film transistors has been derived based on an effective charge density approach of Poisson's equation with both exponential deep and tail state terms included. The proposed surface potential calculation is single-piece and eliminates the regional approach. Model predictions are compared to numerical simulations with close agreement, having absolute error in the millivolt range. Furthermore, expressions of the drain current are given for a wide range of operation regions, which have been justified by thorough comparisons with experimental data.

To achieve low threshold current as well as high single mode output power, a graded index separate confinement heterostructure (GRIN-SCH) AlGaInAs/AlGaAs quantum well laser with an optimized ridge waveguide was fabricated. The threshold current was reduced to 8 mA. An output power of 76 mW was achieved at 100 mA current at room temperature, with a slope efficiency of 0.83 W/A and a horizon divergent angle of 6.3°. The maximum single mode output power of the device reached as high as 450 mW.

A novel broad area slotted Fabry-Perot diode laser is designed and fabricated. Using a new semi- analytical method, we introduce effective refractive index perturbations in the form of etched slot features into a conventional 980 nm broad area Fabry-Perot cavity, and the spectral characteristics of the device are expected to be noticeably improved. A low density of slot features is formed by using standard optical lithography and induc- tively coupled plasma dry etching. The experimental results show that the full spectral width at half-maximum is less than 0.4 nm, meanwhile, the thermal shift of the emission spectrum is decreased from 0.26 to 0.07 nm/ C over a temperature range of 10 to 60 C. The improved spectral characteristics of the device are proved to be attributed to such slotted Fabry-Perot laser structures.

A novel asymmetric broad waveguide diode laser structure was designed for high power conversion efficiency (PCE). The internal quantum efficiency, the series resistance, and the thermal resistance were theoretically optimized. The series resistance and the thermal resistance were greatly decreased by optimizing the thickness of the P-waveguide and the P-cladding layers. The internal quantum efficiency was increased by introducing a novel strain-compensated GaAs_0.9P_0.1/InGaAs quantum well. Experimentally, a single 1-cm bar with 20% fill factor and 900 μm cavity length was mounted P-side down on a microchannel-cooled heatsink, and a peak PCE of 60% is obtained at 26.3-W continuous wave output power.The results prove that this novel asymmetric waveguide structure design is an efficient approach to improve the PCE.

Stable self-starting mode-locking states in a compact Ti: sapphire laser incorporating a home-made SBR with low loss double quantum-well and low temperature and surface state hybrid absorber are investigated experimentally. The three mode-locking states, i.e. the passive mode-locking with a saturable absorber, the solition mode-locking and the Kerr-lens mode-locking have been successfully demonstrated. In this laser, chirped mirrors are used for dispersion compensation, and the 18 fs pulses are produced from the Kerr-lens mode-locking at 4.5W pump power, and output power is 150mW.

We report the technique of the ion-implanted semi-insulating GaAs wafer used for passive Q-switched mode locking in double-cladding Yb:fiber laser. The wafer was implanted with 400-keV energy, 1016/cm2 dose As+ions, and was annealed at 600℃ for 20 min. At the pump power of 5W, we achieved output power of 200mW. The repetition rate of envelope of Q-switched mode locking is 50-kHz with a FWHM envelope of 4μs. The repetition rate of mode locked pulse train was found to be 15-MHz. This is the first report of such a kind of laser to the best of our knowledge.