Near-field scanning optical microscopes are widely used in imaging of subwavelength features in various material systems and nanostructures. For a variety of applications, polarization-sensitive near-field probes can provide valuable information on the nature and symmetry of the imaged nanoparticles and emitters. Conventional near-field optical microscopy lacks in-plane polarization sensitivity. Here, we use aligned single-wall carbon nanotubes as polarization-sensitive molecular scale probes to image the transverse near-field components of an optical Hertzian dipole antenna. Because of the Raman ''antenna effect'' in carbon nanotubes, only the near-field components along the nanotube axis are detected. These findings demonstrate that aligned carbon nanotubes can be used as polarization-sensitive near-field detectors.optical antenna ͉ plasmonics
The current trend toward image sensors with ever-increasing pixel counts is prompting continual reductions in pixel area, leading to significant cross-talk and efficiency challenges. The realization of image sensor pixels containing waveguides presents a means for addressing these issues. The fabrication of such pixels is however not straightforward. Conventional waveguides employed in integrated optics are horizontal, but waveguides needed for the proposed sensor must be vertical and integrated with photodetectors. Here, the authors describe a fabrication process for vertical silicon nitride waveguides integrated with silicon photodetectors. The authors describe the etching, deposition, and planarization techniques that enable the formation of silicon nitride waveguides embedded in silicon dioxide. They also describe a fabrication process for silicon photodetectors, including a means for ensuring that their photosensitive areas have sizes consistent with those of photodetectors employed in conventional image sensors. In addition, the authors perform optical and electrical characterization of the fabricated devices. The results demonstrate the ability of the fabricated waveguides to guide light onto the photodetectors with high efficiency.
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