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光物质

2012-05-01 23页 ppt 12MB 15阅读

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光物质nullnull动态光子晶体-光物质Dynamic photonic crystals: Optical matters作用在微纳米粒子上的光力作用在微纳米粒子上的光力光力的分类:散射力、吸收力和梯度力; 计算光力的公式: 梯度力和光势阱的计算公式: 聚焦高斯光束产生的梯度力聚焦高斯光束产生的梯度力聚焦高斯光束中的光梯度力聚焦高斯光束中的光梯度力光物质-动态光子晶体光物质-动态光子晶体光物质:光产生并且维持的有序结构; 特征:动态,可逆; 制备方法:全息,单光束,Z扫描,毛细管,表面等离子体,微纳米粒子混装等。利用全息方...
光物质
nullnull动态光子晶体-光物质Dynamic photonic crystals: Optical matters作用在微纳米粒子上的光力作用在微纳米粒子上的光力光力的分类:散射力、吸收力和梯度力; 计算光力的公式: 梯度力和光势阱的计算公式: 聚焦高斯光束产生的梯度力聚焦高斯光束产生的梯度力聚焦高斯光束中的光梯度力聚焦高斯光束中的光梯度力光物质-动态光子晶体光物质-动态光子晶体光物质:光产生并且维持的有序结构; 特征:动态,可逆; 制备方法:全息,单光束,Z扫描,毛细管,面等离子体,微纳米粒子混装等。利用全息方法制备光物质利用全息方法制备光物质Z扫描制备光物质的物理机制Z扫描制备光物质的物理机制Focused laser beam from a solid-state laser (532 nm) Objective lens: x 5 Colloidal liquid: PS spheres uniformly distributed in water Diameter and concentration of PS spheres: 1.9 m & 10% Sample cell thickness: 50 m Z扫描过程中粒子分布的演变Z扫描过程中粒子分布的演变 A two-dimensional simulationZ扫描过程中样品透过率随入射功率的变化Z扫描过程中样品透过率随入射功率的变化Disordered state: an attenuation of the transmitted intensity is observed at the focus point; Intermediate state: small peaks begin to appear at the focus point; Ordered state: an enhancement in the transmitted intensity is observed at the focus point.无序-有序相变和自透明现象无序-有序相变和自透明现象Record of the transmitted light intensity (zero-order diffraction spot) by using a CCD (a) and (b): far from the focus point; (c) and (d): close to the focus point;(e): very near to the focus point; (f): at the focus point; (g) just after the focus point; (h)-(l): leave the focus point. 衍射图样与物质有序度之间的关系衍射图样与物质有序度之间的关系S. Főrster et al., Nat. Mater. 6, 888 (2007).Z扫描过程中衍射图样的演变Z扫描过程中衍射图样的演变Disordered state: uniform Gaussian distribution;  amorphous material Intermediate state: Debby-Scherer rings;  polycrystalline Ordered state: Bragg diffraction peaks (spots);  single crystal光物质晶格常数的计算光物质晶格常数的计算The lattice constant and transverse size of the formed ordered structure may be derived by deliberately analyzing the position and half-width of the diffraction peaks.光物质质量与操纵功率之间的关系光物质质量与操纵功率之间的关系 A significant broadening of the transmission peak is observed with increasing trapping power. However, a narrowing of the transmission peak appears at high trapping powers; Accordingly, the enhancement factor decreases first and then increases. 光物质质量与操纵功率之间的关系光物质质量与操纵功率之间的关系 Based on the diffraction pattern, we conclude that the best optical matter is achieved at Pt ~ 100 mW50 mW100 mW200 mW400 mW600 mW800 mW1400 mW1800 mW基于光物质的全光开关器件基于光物质的全光开关器件 trapping light (532 nm)objective lenscapillary containing aqueous solution of PS spheres optical fiber connected to broadband source (1.54 m)optical fiber connected to spectrometerzxysignal light insignal light outoptical matterorganic glass基于光物质的全光开关器件基于光物质的全光开关器件 xyzoptical fiberoptical fibercapillaryobjectiveDevices fabricated with the help of Photonic Manufacture Service Ltd.毛细管中的光场分布毛细管中的光场分布x-y planey-z planex-z planeThe field intensity distribution inside the capillary indicates approximately the distribution of PS spheres and the shape of the optical matter.光物质的形貌和衍射图样光物质的形貌和衍射图样(a) Dumbbell shape, much larger than the focus size (~5 m) (b) Elongated hexagonal diffraction patternxyaboptical matterxy开关过程中粒子分布的演变开关过程中粒子分布的演变abcdefghif可重复的光开关操作可重复的光开关操作In all cases, an extinction ratio al large as ~20 dB is achieved; The switching-on time (~second) is much shorter than the switching-off time (~minute); The optical matter can live a long time (several minutes) after the trapping light is removed; The recovery of the system to the disordered state depends on trapping power. 光物质的产生过程与操纵功率的关系光物质的产生过程与操纵功率的关系Fermi-Dirac Function:The rise time decreases from 7.5 to 0.55 s when the trapping power is increased from 100 to 900 mW.Jin Liu et al., Opt. Lett. (in press).光物质的湮灭过程与操纵功率的关系光物质的湮灭过程与操纵功率的关系 The switching-off process can be approximated by a steady state followed by an exponential decay; It is governed initially by van der Waals force followed by Brownian motion due to thermal agitation. The long lifetime implies possible applications in optical memory (temporary storage) and display.
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