Plasmonic near-field scanning nanoscope with a cross-polarization detection technique

A cross-polarization detection technique was introduced to enhance the signal-to-noise ratio (SNR) of a plasmonic near-field scanning nanoscope (PNSN) using the anisotropic reflection from a metallic ridge nano-aperture. Assuming that the nano-aperture is an resistor-inductor-capacitor-equivalent circuit, we propose an analytic circuit model to quantitatively predict the relationship between the copolarization and cross-polarization signals of the PNSN. It was found that the magnitude of the cross-polarization signal has an opposite trend with respect to the copolarization signal, providing a larger PNSN signal. We demonstrated the PNSN with dual channels for detecting both polarization signals. The performance of the PNSN was characterized by recording images of heterogeneous nanostructures in dynamic random access memory patterns and we enhanced the SNR of the images by a factor of 2.7–4.9.