Waveguiding molecular fiber self-assembled from organic dye molecules

纳米到微米级的光引导和操纵是实现微型化光子电路的关键技术，在高速微处理器和通信设备中具有广阔的应用前景。因此，人们对半导体和有机材料构成的有源介质光波导进行了深入的研究。光子晶体和等离子体波导管也因其在纳米尺度上操纵光的潜力而引起了人们的极大关注。我们发现有机染料分子硫氰酸在水溶液中自组装成纤维状聚集体，其长度可达~250μm，起到了有源波导的作用。这种纤维具有很高的弹性，可以弯曲到亚微米范围内的曲率半径。用新研制的激光扫描光学显微镜定量研究了弯曲光纤的光波导效率(光学损耗)。我们尝试通过控制自组装过程来控制硫氰酸纤维的形状。在高度潮湿的条件下，将含长烷基的硫氰酸氯仿溶液滴在玻璃上。结果表明，溶液蒸发后可自组装成直径为5~30μm的规整环。研究发现，这些光环沿着光环引导它们的荧光。

Guiding and manipulating light on nano- to micrometer scales are key technologies to realize miniaturized photonic circuits, which have promising applications in high-speed microprocessors and telecommunication devices. Therefore, active dielectric waveguides on such scales constructed from semiconductors and organic materials have been intensively studied. Photonic crystals and plasmon waveguides have also attracted a great deal of attention due to their potential for manipulating light on the nanometer scale.We found that the organic dye molecule thiacyanine in aqueous solution self-assembles into fiber-shaped aggregates with a length of up to〜250μm that function as the active waveguides. The fibers are highly flexible and can be bent with a radius of curvature down to the sub-micrometer range. The waveguiding efficiencies (optical losses) of the bent fibers were quantitatively investigated by a newly developed laser scanning optical microscopy. It was found that the bending loss of the fibers is significantly low.We attempted to control the shape of the thiacyanine fiber by controlling the self-assembly process. Chloroform solutions of thiacyanine having long alkyl groups were drop-cast on a glass under highly humid conditions. It was found that well-defined rings with diameters of 5-30 μm were self-assembled after the solution were evaporated. It was found that the rings guided their fluorescence along the rings.