Mendes Sergio B, Bradshaw John Thomas, Saavedra S Scott
Department of Chemistry, University of Arizona, 1306 East University Boulevard, Tucson, Arizona 85721, USA.
Appl Opt. 2004 Jan 1;43(1):70-8. doi: 10.1364/ao.43.000070.
A technique to determine the angular orientation of a molecular assembly bound to the surface of a planar optical waveguide of arbitrary structure is described. The approach is based on measuring the absorption dichroic ratio by using the waveguide evanescent fields with orthogonal polarizations (TE, TM) and the same mode order to probe two molecular assemblies, (i) a reference sample composed of an isotropic orientation distribution of dipoles and (ii) a sample of interest. The isotropic sample is used to characterize the waveguide structure, which then allows the orientation parameters of a molecular assembly under investigation to be determined from a measured dichroic ratio. The method developed here is particularly important for applications in gradient-index and multilayer planar waveguide platforms because in those cases the extension of previously reported approaches would require a full experimental characterization of the guiding structure, which would be problematic and may yield inaccurate results.
描述了一种确定与任意结构的平面光波导表面结合的分子组装体角取向的技术。该方法基于利用具有正交偏振（TE、TM）且模式阶数相同的波导倏逝场来测量吸收二向色比，以探测两个分子组装体，（i）由偶极子各向同性取向分布组成的参考样品，以及（ii）感兴趣的样品。各向同性样品用于表征波导结构，进而能够根据测得的二向色比确定所研究分子组装体的取向参数。这里开发的方法对于梯度折射率和多层平面波导平台中的应用尤为重要，因为在这些情况下，先前报道方法的扩展将需要对波导结构进行全面的实验表征，这会带来问题并且可能产生不准确的结果。
