Geometric effects in designing bow-tie nanoantenna for optical resonance investigation

In this paper, an investigation on the topic of the bow-tie nanoantenna for optical application is carried out. Based on the broad band calculations in the visible and near infrared range of the optical spectrum implemented through the finite integration technique, we focus our study on such nanoantenna's near-field optical properties. It is found that characterized by surface plasmon resonance, highly localized field are found in the gap between the two components of the bow-tie nanoantenna. In addition, such field enhancement is observed to be dependent on the geometric effects, such as the angle and the tip size of the apex, the spacing and the length. A systemic and detailed demonstration of these effects is provided in this study for nanoantenna's design purpose. This bow-tie nanoantenna can be easily combined with the microscope in order to provide a strong light spot for sufficient illumination when probing the near-field properties in microscopy.