Performance of an embedded optical vector matrix multiplication processor architecture

An embedded architecture of optical vector matrix multiplier (OVMM) is presented. The embedded architecture is aimed at optimising the data flow of vector matrix multiplier (VMM) to promote its performance. Data dependence is discussed when the OVMM is connected to a cluster system. A simulator is built to analyse the performance according to the architecture. According to the simulation, Amdahl's law is used to analyse the hybrid opto-electronic system. It is found that the electronic part and its interaction with optical part form the bottleneck of system.

Optical properties of Mn+ doped GaAs

The above work was supported by the national Basic Research Program of China (2006cb604904, 2006cb604908), the hi-tech R & D program of China (2006aa03z0408, 2006aa03z0404), the scientific research Fund of Central South University of Forstry and Technology.

微图案化新方法及在有机光电器件加工中的应用

有机半导体材料正以其光电性能优异、生产成本低廉，加工工艺简单，选材范围宽广，性质调节方便，易于制成大面积器件，与柔性基底结合性好对器件适度弯曲或扭曲而光电性能无明显改变等显著优点，吸引了世界范围内的目光。新的加工方法在有机微电子器件产生、发展和应用中发挥着技术推动力的作用。而从传统的硅基材料为基础的无机微电子中发展起来的光刻工艺，由于制作成本非常昂贵，工艺十分复杂，对环境要求苛刻，不适宜大面积生产，很难制作尺寸小于100nm的图形，而且大多数有机材料的光电性能在光刻胶、显影液等溶液中会大幅的下降，所以不适于有机器件的加工，因此目前开发适合有机材料的廉价大面积加工方法成为研究的焦点。本论文在软刻蚀技术基础上，以机械瓤附力或毛细力为图案化驱动力提出了多种有机电子器件加工方法，并取得了初步的结果。主要有三种方法：金属传递打印、热剥离、冰模板方法。（1）利用聚合物粘弹性随温度和饱和溶剂处理时间变化的规律，通过调控金属薄膜和模板及金属薄膜和聚合物薄膜之间界面相互作用力，发展出以机械粘附力作为图案化驱动力的金属传递打印（MTP）方法。它可以适用于多种材料例如Au、AI等金属和PS、PMMA等多种聚合物。这种方法的分辨率目前在5协m左右。与其它打印技术相比MTP的一个显著的优点是它可以形成多层结构，这种结构在微电子电路（如欧姆接触等方面）中有着巨大的潜在应用价值。为展示金属传递打印在有机电子器件加工中的应用，我们将MTP用于有机场效应晶体管（OFETs）的加工，并在-3cm*3cm的Si片上形成大面积晶体管器件。这些器件的场效应迁移率-0.0193士0.0038cm2V-1s-1。（2）发展了一种用环氧树脂模板为模板图案化的方法一热剥离（Hotlift-off）。它是一种利用机械薪附力为图案化驱动力的方法，所以适用材料范围非常广泛，既可以加工有机电子器件的有源部分一有机半导体材料，也可以加工有机电子器件的金属电极部分，是一种多功能的方法。我们将热剥离用于有机晶体管和有机发光二极机管的加工。这些器件的性能与用其它方法加工的器件性能相当。（3）我们用冰为模板实现了聚合物的图案化，因为大多数聚合物溶液对冰模板不会产生溶解、溶胀作用，所以这种方法适用于许多聚合物材料如P3HT、PvK和PMMA等。这种方法与其它使用PDMS、硅片或金属为模板的方法相比最突出的优点是冰模板非常容易被除去。所以使用冰模板方法可以加工出多种别的方法无法胜任的聚合物结构如多元聚合物结构，自由无支撑的聚合物结构，聚合物微沟道。以上这些图案化技术具有快速大面积图案化、可在开放的空气环境中操作的优点，为发展适宜于未来塑性电子器件卷帘式（reel to reel）的加工过程提供新思路，促进了塑性电子学的发展。

Fabrication of Silicon-Based Template-Assisted Nanoelectrode Arrays and Ohmic Contact Properties Investigation

A convenient fabrication technology for large-area, highly-ordered nanoelectrode arrays on silicon substrate has been described here, using porous anodic alumina (PAA) as a template. The ultrathin PAA membranes were anodic oxidized utilizing a two-step anodization method, from Al film evaporated on substrate. The purposes for the use of two-step anodization were, first, improving the regularity of the porous structures, and second reducing the thickness of the membranes to 100 similar to 200 nm we desired. Then the nanoelectrode arrays were obtained by electroless depositing Ni-W alloy into the through pores of PAA membranes, making the alloy isolated by the insulating pore walls and contacting with the silicon substrates at the bottoms of pores. The Ni-W alloy was also electroless deposited at the back surface of silicon to form back electrode. Then ohmic contact properties between silicon and Ni-W alloy were investigated after rapid thermal annealing. Scanning electron microscopy (SEM) observations showed the structure characteristics, and the influence factors of fabrication effect were discussed. The current voltage (I-V) curves revealed the contact properties. After annealing in N-2 at 700 degrees C, good linear property was shown with contact resistance of 33 Omega, which confirmed ohmic contacts between silicon and electrodes. These results presented significant application potential of this technology in nanosize current-injection devices in optoelectronics, microelectronics and bio-medical fields.

GAAS/GAALAS GRADED INDEX SEPARATE CONFINEMENT SINGLE QUANTUM-WELL SINGLE-MODE WAVE-GUIDE ELECTROABSORPTION LIGHT-MODULATOR

A GaAs/GaAlAs graded-index separate confinement single quantum well heterostructure single-mode ridge waveguide electroabsorption modulator was fabricated and investigated. For the modulator with a quantum well width of 100 angstrom and device length of 700-mu-m, an on/off ratio of 29.7 dB and estimated absorption insertion loss of 3 dB were obtained for TE polarised light with wavelength 8650 angstrom, and for TM polarisation the on/off ratio was 28.5 dB. With a switching voltage of 1 V, an on/off ratio of 15 dB was achieved. Photocurrent spectra exhibited a red shift of 600 angstrom of the absorption edge when the voltage applied to the PIN diode was varied from 0.5 to -7 V. The corresponding shift of the room temperature exciton peak energy was 96 meV.

5.3-W Nd:YVO_4 passively mode-locked laser by a novel semiconductor saturable absorber mirror

We report a diode end-pumped continuous wave (CW) passively mode-locked Nd:YVO4 laser with a homemade semiconductor saturable absorber mirror (SESAM). The maximum average output power is 5.3 W at the incident pump power of 17 W, which corresponds to an optical-optical conversion efficiency of 31.2% and slope efficiency of 34.7%. The corresponding optical spectrum has a 0.2-nm full width at half maximum (FWHM), and the pulse repetition rate is 83 MHz.

A Broadband Long-Wavelength Superluminescent Diode Based on Graded Composition Bulk InGaAs

A novel unselective regrowth buried heterostructure long-wavelength superluminescent diode （SLD） with a graded composition bulk InGaAs active region is developed by metalorganic vapor phase epitaxy （MOVPE）. At a 150mA injection current, the full width at half maximum of the emission spectrum of the SLD is about 72nm, ranging from 1602 to 1674nm. The emission spectrum is smooth and flat. The ripple of the spectrum is less than 0.3dB at any wavelength from 1550 to 1700nm. An output power of 4.3mW is obtained at a 200mA injection current under continuous-wave operation at room temperature. This device is suitable for the applications of light sources for gas detectors and L-band optical fiber communications.

A Wavelength Tunable DBR Laser Integrated with an Electro Absorption Modulator by a Combined Method of SAG and QWI

We report a wavelength tunable electro-absorption modulated DBR laser based on a combined method of SAG and QWI. The threshold current is 37mA and the output power at 100mA gain current is 3.5mW. When coupled to a single-mode fiber with a coupling efficiency of 15% ,more than a 20dB extinction ratio is observed over the change of EAM bias from 0 to -2V. The 4.4nm continuous wavelength tuning range covers 6 channels on a 100GHz grid for WDM telecommunications.

Contrastive study of two SESAMs for passive mode-locking in Nd:YVC>4 laser with low pump power

Two semiconductor saturable absorber mirrors (SESAMs), of which one is coated with 50% reflection film on the top and the other is not, were contrastively studied in passively mode-locked solid-state lasers which were pumped by low output power laser diode (LD). Experiments have shown that reducing the modulation depth of SESAM by coating partial reflection film, whose reflectivity is higher than that between SESAM and air interface, is an effective method to get continuous wave (CW) mode-locking instead of Q-switched mode-locking (QML) in low power pumped solid-state lasers. A simple Nd:YVO4 laser pumped by low power LD, in which no water-cooling system was used, could obtain CW mode-locking by the 50% reflector coated SESAM with average output power of ~ 20 mW

Passively Mode Locked Diode-End-Pumped Yb∶YAB Laser with High Reflectivity Type Semiconductor Saturable Absorption Mirror

利用金属有机气相淀积方法生长了一种新型吸收体:高反射率半导体可饱和吸收镜.用这种吸收体兼作端镜,实现了1.044μm半导体端面泵浦Yb∶YAB激光器被动锁模,脉冲宽度为3.05ps,重复率为375MHz,输出功率为45mW.

Graded tensile-strained bulk InGaAs/InP superluminescent diode with very wide emission spectrum

A kind of novel broad-band superluminescent diodes (SLDs) using graded tensile-strained bulk InGaAs is developed. The graded tensile-strained bulk InGaAs is obtained by changing only group-III trimethyl-gallium source flow during low-pressure metal organic vapor-phase epitaxy. At the injection current of 200 mA, the fabricated SLDs with such structure demonstrate full-width at half-maximum spectral width of 106 nm and the output light power of 13.6 mW, respectively.

Integrated electroabsorption-modulated DFB laser by using an improved butt-joint method

An improved butt coupling method is used to fabricate an electroabsorption modulator (EAM) monolithically integrated with a distributed feedback (DFB) laser. The obtained electroabsorption-modulated laser (EML) chip with the traditional shallow ridge exhibits very low threshold current of 12 mA, output power of more than 8 mW, and static extinction ratio of -7 dB at the applied bias voltage from 0.5 to -2.0 V.

800nm Semiconductor Absorber with Low Temperature Method and Surface State Method Combined Absorber for Kerr Lens Modelocking of Ti∶Al2O3 Laser

A novel 800nm Bragg mirror type of semiconductor saturable absorption mirror with low temperature method and surface state method combined absorber is presented.With which passive Kerr lens mode locking of Ti∶Al2O3 laser pumped by argon ion laser is realized,which produces pulses as short as 40fs.The spectrum bandwidth is 56nm,which means that it can support the modelocking of 20fs.The pulse frequency is 97.5MHz;average output power is 300mW at the pump power of 4.45W.