Dynamic Plasmonic Control in Bowtie Nanostructure: The Role of Gap Variation and Polarization Orientation

Sub-wavelength nanoparticles (NPs) with small gaps play a vital role in the enhancement of light-matter interaction. However, simultaneous achievement of enhancement due to significant light-matter interaction and attaining high optical response for detection still remains challenging. In this study, we present a simple bowtie nanostructure with flexible fabrication techniques offering a substantial near-field electric enhancement (NFEE) with a huge operational wavelength ranging from visible to near-infrared (NIR) regions. The NFEE factor can reach a high value of 181 thus providing a large window of electric field enhancements. The simulations showed that the proposed model can enhance the electromagnetic hotspots by continuously varying the gap between the structure and by changing the direction of the incident electric field. Moreover, the proposed model has produced multiple hotspots useful for applications in SERS and much more. The field enhancements and localized surface plasmon resonance (LSPR) shifting for different gap sizes and polarizations provide valuable insights for surface-enhanced Raman spectroscopy (SERS) which leads to achieving a SERS enhancement factor of about 109 useful for biosensing applications.