Pereira Marcelo B, Craven Jill S, Mendes Sergio B
Instituto de Física, UFRGS, CP 15051, Porto Alegre, RS 91501-970, Brazil.
Opt Eng. 2010 Dec;49(12):124601. doi: 10.1117/1.3520063.
We report a technique to substantially boost the spectral bandwidth of a conventional waveguide grating coupler by using a solid immersion cylindrical lens at the aplanatic condition to create a highly anamorphic beam and reach a much larger numerical aperture, thus enhancing the spectral bandwidth of a free-space propagating optical beam coupled into a single-mode planar integrated optical waveguide (IOW). Our experimental results show that the broadband IOW spectrometer thus created almost doubles (94% enhancement) the coupled spectral bandwidth of a conventional configuration. To exemplify the benefits made possible by the developed approach, we applied the technique to the broadband spectroscopic characterization of a protein submonolayer; our experimental data confirm the enhanced spectral bandwidth (around 380-nm) and illustrate the potentials of the developed technology. Besides the enhanced bandwidth, the broadband coupler of the single-mode IOW spectrometer described here is more robust and user-friendly than those previously reported in the literature and is expected to have an important impact on spectroscopic studies of surface-adsorbed molecular layers and surface phenomena.
我们报告了一种技术，通过在齐明条件下使用固体浸没柱面透镜来大幅提高传统波导光栅耦合器的光谱带宽，以产生高度非等方性光束并实现大得多的数值孔径，从而增强耦合到单模平面集成光波导（IOW）中的自由空间传播光束的光谱带宽。我们的实验结果表明，由此创建的宽带IOW光谱仪使传统配置的耦合光谱带宽几乎翻倍（增强了94%）。为了例证所开发方法带来的益处，我们将该技术应用于蛋白质亚单层的宽带光谱表征；我们的实验数据证实了增强的光谱带宽（约380纳米），并说明了所开发技术的潜力。除了增强的带宽外，这里描述的单模IOW光谱仪的宽带耦合器比文献中先前报道的更坚固且用户友好，预计将对表面吸附分子层和表面现象的光谱研究产生重要影响。
