High-Brightness Low-Divergence Tapered Lasers with a Narrow Taper Angle

High-brightness tapered lasers with photonic crystal structures are designed and fabricated.A narrow taper angle is designed for the tapered section.The device delivers an output power of 3.3 W and a maximum wall-plug efficiency of 43%.The vertical beam divergence is around 110 at different currents.Nearly diffraction-limited beam qualities for the vertical and lateral directions are obtained.The lateral beam quality factor M~2 is below 2.5 and the vertical M~2 value is around 1.5 across the whole operating current range.The maximum brightness is 85 MW·cm~(-2)sr~(-1).When the current is above 3.3 A,the brightness is still above 80 MW·cm~(-2)sr~(-1).     

导向剂法制备SAPO-11分子筛及其加氢异构化性能

采用导向剂法在模板剂用量减半的条件下成功合成小晶粒介孔SAPO-11分子筛。对合成分子筛的晶体结构、形貌、孔结构和酸类型进行表征。以长链烷烃正十二烷作为反应原料,考察Pt负载量为0. 5(wt)%的SAPO-11分子筛的加氢异构化反应性能。结果表明,将模板剂使用量减半合成的SAPO-11分子筛晶粒尺寸约为3μm,介孔比表面积为113. 3m~2/g,介孔孔容为0. 328m~3/g,异构烃收率达到65. 31%。     

Quantum Boltzmann equation solved by Monte Carlo method for nano-scale semiconductor devices simulation

A two-dimensional (2D) full band self-consistent ensemble Monte Carlo (MC) method for solving the quantum Boltzmann equation, including collision broadening and quantum potential corrections, is developed to extend the MC method to the study of nano-scale semiconductor devices with obvious quantum mechanical (QM) effects. The quantum effects both in real space and momentum space in nano-scale semiconductor devices can be simulated. The effective mobility in the inversion layer of n and p channel MOSFET is simulated and compared with experimental data to verify this method. With this method 50nm ultra thin body silicon on insulator MOSFET are simulated. Results indicate that this method can be used to simulate the 2D QM effects in semiconductor devices including tunnelling effect.     

星形超支化聚酯的合成及其光固化

紫外光固化具有快速反应、室温操作、低能消耗和无溶剂少污染等优点,现正以日益增长的速度应用于涂层和粘合剂等领域。然而,常规的线形光固化齐聚体具有缠结的柔性分子链结构,其粘度随着分子量的增大而快速增加,故其可加工性和应用受到很大的限制。     

Monte-Carlo simulation of a compact gamma-ray detector using wavelength-shifting fibers coupled to a YAP scintillation crystal

The production and transportation of fluorescent light produced in wavelength-shifting fibers (WSFs) coupled to YAP scintillation crystal is simulated using the GEANT4 codes. An advantage of the wavelength-shifting fiber readout technique over a direct readout with a position-sensitive photo-sensor is the reduced requirement for position sensitive photomultiplier tube photocathode area. With this gamma-ray detector, the gamma camera is small and flexible and has larger effective field of view and low cost. Simulation results show that a) a mean 12 of photons per 59.5 keV gamma ray interaction is produced in the WSF located nearest to the incident gamma ray, and a spatial resolution of 3.6 mm FWHM is obtained, b) a mean 27 of photons per 140 keV gamma ray interaction is produced and a spatial resolution of 3.1 mm FWHM is obtained. Results demonstrate the feasibility of this concept of a compact gamma-ray detector based on wavelength-shifting fibers readout. However, since the very low photoelectron levels, it is very important to use a photon counting device with good single photo-electron response to readout the WSFs.     

二阶矩阵快速乘法的一个新的算法集合

文献[1]—[4]从不同角度研究了二阶矩阵快速乘的各种问题,所有算法分属于以S算法与W算法为基础的两个算法集合.本文作者深入研究了算法的结构和性质,通过计算机检索,得到一个不属于上述两集合的算法和相应的包含有1048576个算法的封闭的算法集合.     

Comparison of two position sensitive gamma-ray detectors based on continuous YAP and pixellated NaI(TI) for nuclear medical imaging applications

Dedicated position sensitive gamma-ray detectors based on position sensitive photomultiplier tubes (PSPMTs) coupled to scintillation crystals, have been used for the construction of compact gamma-ray imaging systems, suitable for nuclear medical imaging applications such as small animal imaging and single organ imaging and scintimammography. In this work, the performance of two gamma-ray detectors：a continuous YAP scintillation crystal coupled to a Hamamastu R2486 PSPMT and a pixellated NaI(TI) scintillation array crystal coupled to the same PSPMT, is compared. The results show that the gamma-ray detector based on a pixellated NaI(TI) scintillation array crystal is a promising candidate for nuclear medical imaging applications, since their performance in terms of position linearity, spatial resolution and effective field of view (FOV) is superior than that of the gamma-ray detector based on a continuous YAP scintillation crystal. However, a better photodetector (Hamamatau H8500 Flat Panel PMT, for example) coupled to the continuous crystal is also likely a good selection for nuclear medicine imaging applications.     

具有HfN/HfO2栅结构的p型MOSFET中的负偏置-温度不稳定性研究

研究了HfN/HfO2高K栅结构p型金属-氧化物-半导体(MOS)晶体管(MOSFET)中,负偏置-温度应力引起的阈值电压不稳定性(NBTI)特征.HfN/HfO2高K栅结构的等效氧化层厚度(EOT)为1.3nm,内含原生缺陷密度较低.研究表明,由于所制备的HfN/HfO2高K栅结构具有低的原生缺陷密度,因此在p-MOSFET器件中观察到的NBTI属HfN/HfO2高K栅结构的本征特征,而非工艺缺陷引起的;进一步研究表明,该HfN/HfO2高K栅结构中观察到的NBTI与传统的SiO2基栅介质p-MOSFET器件中观察到的NBTI具有类似的特征,可以被所谓的反应-扩散(R-D)模型表征: HfN/HfO2栅结构p-MOSFET器件的NBTI效应的起源可以归为衬底注入空穴诱导的界面反应机理,即在负偏置和温度应力作用下,从Si衬底注入的空穴诱导了Si衬底界面Si-H键断裂这一化学反应的发生,并由此产生了Si+陷阱在Si衬底界面的积累和H原子在介质层内部的扩散,这种Si+陷阱的界面积累和H原子的扩散导致了器件NBTI效应的发生.     

Twist characteristics of the ultraviolet-written long-period fiber gratings

Twist characteristics of the ultraviolet-written long period fiber gratings (UV-LPFGs) are investigated in this paper. It was found experimentally that the resonance wavelength of the UV-LPFG shifts to short side proportional to square of the torsion rate, when it is twisted in both directions of clockwise and counter-clockwise, which is different from that of LPFGs written by CO_2 lasers, but similar with that of the corrugated LPFGs. The phenomena can be explained by mechanisms of static compression in twisting and index change caused by photo-elastic effect.     

50mJ超短脉冲KrF激光系统的参数优化

 介绍了原子能院建立的钛宝石/KrF混合型激光装置，主要输出参数的测量和性能优化。放电泵浦准分子激光器采用离轴放大结构，结合棱镜对进行GVD补偿，获得50mJ，220fs的紫外超短脉冲。用40cm透镜聚焦，靶上功率密度达到10¹⁷ W/cm²。