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The Yarlung Zangbo ophiolite represents the ocean crustal residue of the Mesozoic Tethys. In this ophiolite belt, there are two suites of volcanic sequences. One is Late Jurassic-Early Cretaceous metabasalts, and the other is Early Cretaceous pillow basalts. These two suites of volcanic rocks are significantly different in time and space patterns and geochemistry. Based on an investigation on their geochemical characteristics, the authors would have a discussion on the two stages of the ocean crustal evolution of the Mesozoic Tethys.The evolution of the Mesozoic Tethys went through three stages, namely the early rift valley, the intermediate ocean crustal development and the last closing stage. The development of oceanic crust experienced the early discontinuous spreading stage which formed the metabasalt and the late continuous spreading stage which produced the Early Cretaceous oceanic crust. 相似文献
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Tunable wavelength filters using polymer long-period waveguide gratings based on metal-cladding directly defined technique 下载免费PDF全文
In this work, long-period waveguide grating-based tunable wavelength filters using organic–inorganic grafting poly(methyl methacrylate)(PMMA) materials are designed and fabricated by metal-cladding directly defined technique.The thermal stabilities and optical properties of the organic–inorganic grafting PMMA core materials are analyzed. Structures and performance parameters of the waveguide gratings and self-electrode heaters are designed and simulated. The contrast of the filter is about 15 d B and the resonant wavelength can be tuned by different electric powers applied to the metal-cladding self-electrode heaters. The temperature sensitivity is 3.5 nm/℃ and the switching time is about 1 ms. The technique is very suitable for realizing the optoelectronic integrated wavelength-division-multiplexing systems. 相似文献
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Visible light variable optical attenuators(VOA) are essential devices in the application of channel power regulation and equalization in wavelength-division multiplexing cross-connect nodes in plastic optical fiber(POF) transmission systems.In this paper, a polymer/silica hybrid waveguide thermo–optic attenuator based on multimode interference(MMI) coupler is designed and fabricated to operate at 650 nm. The single-mode transmission condition, MMI coupler, and transition taper dimensions are optimized through the beam propagation method. Thermal analysis based on material properties provides the optimized heater placement angle. The fabricated VOA presents an attenuation of 26.5 dB with a 21-mW electrical input power at 650 nm. The rise time and fall time are 51.99 and 192 μs, respectively. The time–stability measurement results prove its working reliability. 相似文献
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低功耗聚合物Mach-Zehnder热光开关 总被引:3,自引:0,他引:3
采用传统的半导体工艺制作了聚合物Mach-Zehnder型热光开关.利用扫描电镜观测波导形貌,通过红外摄像机观测波导的近场输出光斑,在通信波段1 550 nm波长下测试了器件的输出光谱.在电极上施加直流信号,测得热光开关的消光比为-15 dB,驱动功率为16 mW.引入直流偏置网络,获得了器件的开关特性曲线,经测量开关上升时间为1.2 ms,下降时间为0.8 ms. 相似文献
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从雅鲁藏布江蛇绿岩带中的两套火山岩探讨中生代特提斯洋壳的演化 总被引:2,自引:0,他引:2
雅鲁藏布江蛇绿岩代表中生代特提斯的洋壳残余,其中包括两套火山岩:一套为晚侏罗—早白垩世的变玄武岩;另一套为早白垩世的枕状玄武岩。两套火山岩具有不同的时空格局和明显的地球化学差异。通过对两套火山岩的地球化学研究,讨论了中生代特提斯洋壳演化的两个阶段。中生代特提斯的演化经历了早期裂谷阶段、中期洋壳发育阶段以及末期闭合阶段。洋壳的演化包括早期的不连续扩张阶段,形成了变玄武岩和晚期的扩张阶段,发育了枕状玄武岩。 相似文献
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采用新型聚合物材料Norland紫外固化胶(NOA)制备了聚合物M-Z型热光开关器件。对NOA薄膜材料的光学性质进行了表征,采用感应耦合等离子体(ICP)方法制备出形貌良好的波导器件。测得在1 550 nm波长下,长2.2 cm的直波导插入损耗为8.3 dB。在电极上施加直流信号,测得热光开关的消光比为11 dB,驱动功率为85 mW。引入直流偏置网络,获得了器件的开关特性曲线,测得开关器件的上升时间为1.085 ms,下降时间为489.5μs。实验结果表明:NOA材料在热光开关及其它聚合物光波导集成器件的制备中具有很大的应用潜力。 相似文献
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制作了基于KMnF_3∶Yb~(3+),Er~(3+)纳米晶材料的工作波长655 nm的聚合物平面光波导放大器。材料的吸收光谱表明,KMnF_3∶Yb~(3+),Er~(3+)纳米晶在980 nm附近有很强的吸收。在980 nm激光的激发下,由于Er~(3+)和Mn2+能级之间的能量传递,KMnF_3∶Yb~(3+),Er~(3+)纳米晶产生了很强的红色上转换发光。根据KMnF_3∶Yb~(3+),Er~(3+)纳米粒子的发光特性,制备了KMnF_3∶Yb~(3+),Er~(3+)NCs-PMMA复合材料,用其作为芯层设计了掩埋形结构光波导放大器,利用传统的半导体工艺完成器件制备。器件测试结果表明,当655 nm信号光功率为0.1 m W、980 nm泵浦功率为260 m W时,器件获得了2.7 d B的相对增益。 相似文献
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