Effects of UV photon irradiation on SiOx (0 < x < 2) structural properties

Thin films of a-SiO_x (0 < x < 2) were prepared by reactive r.f. magnetron sputtering from a polycrystalline-silicon target in an Ar/O₂ gas mixture. The oxygen partial pressure in the deposition chamber was varied so as to obtain films with different values of x. The plasma was monitored, during depositions, by optical emission spectroscopy (OES) system. Energy dispersive X-ray (EDX) measurements and infra-red (IR) spectroscopy were used to study the compositional and structural properties of the deposited layers.Structural modifications of SiO_x thin films have been induced by UV photons’ bombardment (wavelength of 248 nm) using a pulsed laser. IR spectroscopy and X-ray photoemission spectroscopy (XPS) were used to investigate the structural changes as a function of x value and incident energy. SiO_x phase separation by spinodal decomposition was revealed. The IR peak position shifted towards high wavenumber values when the laser energy is increased. Values corresponding to the SiO₂ material (only Si⁴⁺) have been found for laser irradiated samples, independently on the original x value. The phase separation process has a threshold energy that is in agreement with theoretical values calculated for the dissociation energy of the investigated material.For high values of the laser energy, crystalline silicon embedded in oxygen-rich silicon oxide was revealed by Raman spectroscopy.     

我国有线电视事业的现状和发展

本文详细系统地介绍了我国有线是视发展历史和现状，及其经营和管理方法。重点介绍了北美的ＣＡＴＶ技术发展动向。最后，指出我国ＣＡＴＶ事业发展中的应用重视的问题。     

4×622Mb／sWDM40km光通信系统实验

本文完成了我国第一个４×６２２Ｍｂ／ｓ波分复用（ＷＤＭ）光通信系统实验，使单根光纤线路通信容量达２．４Ｇｂ／ｓ。该系统以ＤＦＢ－ＬＤ为光源，工作波长在１．５５μｍ附近，ＬＤ的工作频率稳定度优于±１５０ＭＨｚ，信道间隔２ｎｍ左右，无中继传输距离为４３．６ｋｍ，采用Ｆ－Ｐ调谐光滤波器作为解复用器，接收机灵敏度达－３０ｄＢｍ。     

光纤的淬冷增强原理

本文从拉丝工艺技术的角度出发，讨论了高速、高温拉丝工艺方法对光纤的淬冷增强原理。     

自聚焦棒耦合性能的分析

本文采用光线光学的原理分析了自聚焦棒（ＧＲＩＮ）的光学性能，在折射率分布为抛物线近似的条件下，推导出较为简单的ＧＲＩＮ中的光线轨迹方程，并实验测量了ＧＲＩＮ的耦合效率，从而由理论和实验两方面讨论ＧＲＩＮ的聚焦特性。     

An efficient lasing action from pyrromethene 556 dye-doped organically modified silicates

Organically modified solid-state silicates (ORMOSILS) doped with a new laser dye 1,3,5,7,8-pentamethylpyrromethene-2,6-disulfonate-BF₂ complex (pyrromethene 556) have been synthesized by a sol-gel method and the compositional effects on pore characteristics, fluorescence and lasing properties have been investigated. It is found that the use of dimethylsulfoxide and γ-glycidoxypropyltrimethoxysilane could greatly change the structure properties of sol-gel derived ORMOSILS cage, and thus the fluorescence and lasing properties of the materials could improve significantly. A successful laser oscillation from this dye-doped ORMOSILS sample has been achieved upon pumping with a Q-switched frequency-doubled Nd:YAG laser at 532 nm. A slope efficiency of 54% with a useful lifetime greater than 10,000 shots has been demonstrated at a pump repetition rate of 1 Hz and a pump intensity of 1 J/cm² by using the new ORMOSILS cage on our newly designed laser system. Our results have shown that it is possible to obtain a high-efficiency with a long-lifetime for a compact new laser device by low cost dye-doped solid-state ORMOSILS.     

光纤数字环路载波系统的发展

ＯＤＬＣ是当今用户接入网的新型设备，它一方面可取代端局，解决通信线路紧张和远距离大容量放号问题，另一方面也可满足日益增多的增值业务的需求。本文ＯＤＬＣ技术的基本原理，结合目前国内外常见ＯＤＬＣ系统，总结和对比了其基本特点，优势，并指明ＯＤＬＣ的技术发展方向和中国应用的前景。     

ADSS光缆的力学计算

介绍了ADSS光缆的力学计算，给出了光缆弧垂、张力、应变和悬长等计算公式，并对普遍采用的“悬链线”和“抛物线”两种计算方法加以比较。     

我国有线电视的网络媒体价值

阐述有线电视网络媒体的特点，有线电视网络媒体面临的困境及解决办法，最后展望有线电视网络媒体价值。     

红外半导体激光光镊的实验研究

激光光镊技术是一项在许多科学领域有广阔应用前景的技术。本文详细给出构建一台红外半导体激光光镊的设计思想及实例。由于采用了独特的对大功率多模红外激光选模整形和双透镜陷阱操纵技术等性能价格最优化选择 ,该系统易于构建 ,陷阱操作方便 ,其构建价格仅一般光镊的几十分之一 ,非常适合光镊技术的推广和一般实验室构建