Chemical approaches to controlling light propagation

Saravanamuttu小组研究了通过(I)光学自陷现象和(Ii)具有可见光带隙的微周期结构来控制光传播的方法。对新的无光纤导光方式的需求刺激了这两个领域的研究。(I)当正常发散的光束诱导其自身的波导并作为该波导的束缚解(光学模式)传播时，发生自陷。自陷光束及其特殊的粒子状行为在下一代光学设备中具有潜力，在这种装置中，自陷光束(携带数据信号)在集成光学系统中记录自己的路径；自陷光束的吸引、排斥甚至轨道相互作用可以调制/传输/分裂/放大光信号。以前的研究局限于某些类型的介质--非线性光学(NLO)材料--它们在极其狭窄的条件下对光做出反应。我们的研究不再局限于非线性光学材料，而是研究简单光化学系统中的自陷现象；这为自陷研究提供了更广泛的条件。这项研究承诺提供新的洞察力，甚至是全新形式的自我陷阱现象。(Ii)具有折射率微周期调制的结构可以具有可见光能量的带隙；在带隙中的波长的光可以被紧密地捕获、反射和引导通过晶格中的缺陷。以前的研究主要集中在全介质光子晶体上，理论研究预测金属-介质结构具有极大的带隙增强，但这种结构很难用传统的技术来构建。我们的研究开发了金属-介电聚合物复合材料，通过简单的一步光刻工艺构建金属-介电周期结构。我们还研究了彩虹般的自然周期结构--包括菊石头足类化石。了解这些7000万年前化石的复杂结构和光学特性，可能会为合成光子晶体的设计提供洞察力。

The Saravanamuttu Group examines ways of controlling light propagation through (i) optical self-trapping phenomena and (ii) microperiodic structures with bandgaps for visible light. Research in both fields is stimulated by demands for new optical fibre-free ways to guide light. (i) self-trapping occurs when a light beam that normally diverges induces its own waveguide and propagates as a bound solution (optical mode) of this waveguide. Self-trapped beams and their extraordinary particle-like behaviour have potential in next-generation optical devices in which self-trapped beams (carrying data signals) inscribe their own routes in an integrated-optics system; attractive, repulsive and even orbiting interactions of self-trapped beams could modulate/transfer/split/amplify light signals. Previous studies were restricted to certain types of media - nonlinear optical (NLO) materials - which respond to light under an extremely narrow range of conditions. Our research moves away from NLO materials and examines self-trapping phenomena in simple photochemical systems; these provide a much broader range of conditions for self-trapping studies. This research promises new insight and even entirely new forms of self-trapping phenomena. (ii) Structures with microperiodic modulations in refractive index can possess bandgaps for visible energies; light at wavelengths in the bandgaps can be tightly trapped, reflected and guided through defects in the lattice. Previous research focused on all-dielectric photonic crystals; theoretical studies predict that metallo-dielectric structures possess greatly-enhanced bandgaps but such structures are difficult to construct with conventional techniques. Our research develops metallo-dielectric polymer composites to construct metallo-dielectric periodic structures through simple, one-step lithographic processes. We also examine iridescent natural periodic structures - including ammonite cephalopod fossils. Understanding the sophisticated structural and optical properties of these 70-million year old fossils may provide insight for the design of synthetic photonic crystals.