1 中兴通讯股份有限公司上海研发中心, 上海 201203
2 浙江大学信息与电子工程学系, 浙江 杭州 310027
从跳频光码分多址(FH-OCDMA)系统的扩频特征出发,推导出具有良好相关性能的扩频码所能达到的最大码容量,再利用二次全等理论为跳频光码分多址系统构造出一种具有最大码容量的扩频码——二次全等跳频码(QCHC),并给出了构造实例。在此基础上,运用光纤布拉格光栅序列作为编解码器设计了一种跳频光码分多址系统的实现方案,并对该系统的性能进行了详细的分析。结果表明,采用二次全等跳频码的跳频光码分多址系统具有设计简单、用户容量大和误码率低等方面的优点。
光通信 跳频光码分多址 二次全等跳频码 光纤布拉格光栅 双光硬限幅器
1 浙江大学信息与电子工程学系，浙江杭州 310027
2 Boston Applied Technologies，Inc．Woburn，MA 01801，USA
基于PLZT波片的相对相位延迟量可变性和其折射率椭球主光轴的可转性，提出后反馈单个PLZT可变可转波片偏振控制器．采用模拟退火算法进行扰动寻优，仿真结果显示这种控制器是有效的：能将任意输入偏振态转换为稳定的线偏振光而其光强达到总光强的98%以上，在控制过程中相移能在限定范围内变化，避免了由复位重置可能引起的波动．
光纤通信 偏振控制器 电光效应 可变可转波片 Optical fiber communication Polarization controller Electro-optic effect PLZT PLZT Rotatable-variable waveplates
Author Affiliations
Abstract
1 Department of Information and Electronic Engineering, Zhejiang University, Hangzhou 310027
2 Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080
A novel fiber Bragg grating (FBG) based chemical sensor using hydrogel, a swellable polymer, as sensitive element is demonstrated. The sensing mechanism relies on the shift of Bragg wavelength due to the stress resulted from volume change of sensitive swellable hydrogel responding to the change of external environment. A polyacrylamide hydrogel fiber grating chemical sensor is made, and the experiments on its sensitivity to the salinity are performed. The sensitivity is low due to the less stress from the shrinking or swelling of hydrogels. Reducing the cross diameter of the grating through etching with hydrofluoric acid can greatly improve the sensitivity of the sensor.
060.2370 fiber optics sensors 350.2770 gratings 160.6060 solgel 160.5470 polymers Chinese Optics Letters
2004, 2(12): 12683
