Characterization of proton-exchanged optical waveguides in ZnO:LiNbO3

We report the first demonstration of proton-exchanged optical planar waveguides in x-cut and z-cut LiNbO₃ doped with 6 mol% ZnO using adipic acid as proton source. These waveguides exhibit a graded index profile which can be modeled by a linear step function with a surface index increase of 0.135 and 0.14 for x-cut and z-cut waveguides, respectively. The diffusion constant D_o and the activation energy Q are characterized optically to be 1.64×10⁹ μm²/h and 88.8 KJ/mol for x-cut waveguides, and 1.478×10⁹ μm²/h and 91.25 KJ/mol for z-cut waveguides, respectively. The diffusion rate along the z-axis is slower than that along the x-axis, whereas the surface index increase on z-cut waveguides is larger than that on x-cut waveguides.     

空拉铜管“缩径”现象研究

揭示了空拉铜管时的“缩径”现象,分析了产生这种现象的原因以及各种工艺条件对其影响的规律。     

单液晶光阀彩色大屏幕投影显示

设计一电路,将彩色图象信息编码到黑白CRT的亮度之中,并将其写入液晶光阀,用白光读出,当编码合适时,读出的象颜色可与原图像一致。本文讨论了这一技术原理并进行了单液晶光阀彩色大屏幕投影的实验验证。     

Structural and gas-sensing properties of nanometre tin oxide prepared by PECVD

A low-temperature plasma-enhanced chemical vapour deposition (PECVD) technique has been employed to produce ultrafine tin oxide powders. The structural features and phase transition of this material have been characterized using differential thermal analysis (DTA), thermogravimetric analysis (TGA), X-ray diffraction, infrared spectroscopy (IR) and transmission electron microscopy (TEM). The oxygen absorption behaviour and gassensing properties have been investigated by electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS) and electrical measurements. Thick film gas sensors made from such ultrafine SnO₂ powders yield better sensitivities than those of normal undoped SnO₂ gas sensors. A gas-sensing reaction mechanism is also proposed.     

Multiresolution learning paradigm and signal prediction

Current neural network learning processes, regardless of the learning algorithm and preprocessing used, are sometimes inadequate for difficult problems. We present a new learning concept and paradigm for neural networks, called multiresolution learning, based on multiresolution analysis in wavelet theory. The multiresolution learning paradigm can significantly improve the generalization performance of neural networks     

Rejection of narrowband interference in DS spread spectrum systemsemploying minimum redundant nonlinear filters

A new nonlinear filter structure, the minimum redundant nonlinear filter (MRNF), for combating narrowband interference in direct sequence spread spectrum systems is proposed. Analytical expressions for the signal-to-noise ratio improvement factors are derived under the condition of single tone interference. The results show that the MRNF provides significantly better performance than the minimum redundant transversal filter     

High-speed Modulation of InGaAs: Sb-GaAs-GaAsP quantum-well vertical-cavity surface-emitting lasers with 1.27-/spl mu/m emission wavelength

1.27-/spl mu/m InGaAs: Sb-GaAs-GaAsP vertical-cavity surface-emitting lasers (VCSELs) were grown by metal-organic chemical vapor deposition and exhibited excellent performance and temperature stability. The threshold current changes from 1.8 to 1.1 mA and the slope efficiency falls less than /spl sim/35% as the temperature raised from room temperature to 70/spl deg/C. With a bias current of only 5 mA, the 3-dB modulation frequency response was measured to be 8.36 GHz, which is appropriate for 10-Gb/s operation. The maximal bandwidth is measured to be 10.7 GHz with modulation current efficiency factor (MCEF) of /spl sim/5.25 GHz/(mA)/sup 1/2/. These VCSELs also demonstrate high-speed modulation up to 10 Gb/s from 25/spl deg/C to 70/spl deg/C.     

连续运转的掺钛蓝宝石激光器

本文报导一种连续波氩离子激光泵浦的掺钛蓝宝石激光器。在氩离子激光功率(全谱线)为10.45瓦且仅用一组腔镜时,获得最大平均功率超过1000mW、调谐范围750～850nm的掺钛蓝宝石激光输出。     

Study on phase behavior–impact strength relationship of unsaturated polyester/polyurethane hybrid polymer network

The phase behavior of a hybrid polymer network (HPN) composed of poly[(propylene glycol maleate)-co-(propylene glycol phthalate)] crosslinked with styrene and polyester–urethane crosslinked with methylene-bis-ortho-chloroaniline was examined. The correlation between phase separation and impact strength of the HPNs is discussed. The composition of HPNs has an effect on their properties.