A tunable photonic crystal(PC) filter is proposed with the twisted nematic(TN) liquid crystal(LC) as a defect layer.The polarization sensitive performance and the eigenmodes are analyzed.The results show that there ar...A tunable photonic crystal(PC) filter is proposed with the twisted nematic(TN) liquid crystal(LC) as a defect layer.The polarization sensitive performance and the eigenmodes are analyzed.The results show that there are two kinds of transmission modes,namely o and e,when the voltage is low.The different modes can be selected by rotating the filter axially.The e mode shifts toward the shorter wavelength side as the applied voltage increases.Then the peaks of two modes merge into each other and the polarization sensitive performance disappears.The photonic band gap is insensitive to the voltage.The tunable range of the filter is 53 nm.展开更多
基金supported by the Talent Introduction Program of Henan University of Technology (No.2007BS041)
文摘A tunable photonic crystal(PC) filter is proposed with the twisted nematic(TN) liquid crystal(LC) as a defect layer.The polarization sensitive performance and the eigenmodes are analyzed.The results show that there are two kinds of transmission modes,namely o and e,when the voltage is low.The different modes can be selected by rotating the filter axially.The e mode shifts toward the shorter wavelength side as the applied voltage increases.Then the peaks of two modes merge into each other and the polarization sensitive performance disappears.The photonic band gap is insensitive to the voltage.The tunable range of the filter is 53 nm.
文摘以氧化石墨凝胶制备的氧化石墨烯(GO)溶胶为前驱体,在100—350℃温度下还原获得不同还原程度的还原氧化石墨烯(rGO)样品,并采用旋涂工艺制备还原氧化石墨烯气敏薄膜元件.采用X射线衍射、拉曼光谱、傅里叶变换红外光谱和气敏测试等手段研究还原温度对样品结构、官能团和气敏性能的影响.结果表明:经热还原处理的氧化石墨烯结构向较为有序的类石墨结构转变,还原温度为200℃时,样品处于GO向rGO转变的过渡阶段,还原温度达到250℃时,则表现出还原氧化石墨烯特性;无序程度随还原温度的升高先由0.85增大至1.59,随后减小至1.41,总体呈现增加趋势;氧化石墨烯表面含氧官能团随还原温度的升高逐渐热解失去,不同含氧官能团的失去温度范围不同;热还原氧化石墨烯具有优异的室温H_2敏感性能,随着还原温度的升高,元件灵敏度逐渐减小,响应-恢复时间逐渐增大,最佳灵敏度为88.56%,响应时间为30 s.
